Device and method for detecting electric leakage of it system

Abstract

A technology related to a device for detecting electric leakage of an IT system is disclosed. An electric leakage detection device used in an IT system comprises an offset generation unit and an amplification unit. The offset generation unit applies a DC offset voltage to a secondary-side neutral point of an insulation unit. The amplification unit is connected between the offset generation unit and a ground. A first amplification unit receives a voltage of a low-voltage terminal which is the other end of the offset generation unit, and amplifies same. A second amplification unit outputs a waveform inverted from the output of the first amplification unit. The electric leakage detection device may further comprise a peak detection unit and a differential comparison unit. The peak detection unit outputs a signal corresponding to a maximum value of the output waveform of the amplification unit, and the differential comparison unit receives the outputs of the first amplification unit and the second amplification unit and compares whether there is a difference in output values. When there is a difference in the output values, resistive leakage can be determined. The phase-balanced resistive leakage can also be detected with a simple structure, and the influence of the capacitive leakage can be excluded. In addition, it is possible to quickly and accurately detect a phase in which a phase-balanced resistive leakage current occurs.

Description

Leakage detection device and detection method for IT systems

[0001] The present invention relates to a leakage current detection device and method for an IT system, and more particularly, discloses a technology for a leakage current detection device and method for an IT system capable of quickly and accurately measuring resistive leakage current using an offset generation unit and an amplifier unit.

[0002] In modern society, countless electrical devices are used, including lighting devices like fluorescent lamps, home appliances like TVs and refrigerators, and transportation devices like subways and electric cars. While electricity makes our lives convenient and efficient, it also carries a dangerous side. Electrical fires and electrocution are prime examples of electrical hazards. In particular, electric shock caused by leakage current can be fatal to humans and livestock, depending on the current, even for a very short period of time—a few milliseconds.

[0003] To prevent electrical accidents, grounding methods such as TN systems, TT systems, and IT systems are used. Among these, the IT grounding method has the advantage of reducing fault current in the event of a grounding system failure, such as a ground fault or current leakage, because it insulates the power system or grounds it with high impedance. In other words, the IT grounding method is an effective system grounding method for preventing electric shock and fire caused by ground faults or current leakage. Because the leakage current is small, power can be maintained without tripping the leakage circuit breaker in the event of a grounding system failure. However, audio and visual alarms must be triggered in the event of a primary current leakage or ground fault.

[0004] IT systems face the challenge of limiting leakage current, making relay operation difficult. To address this, the faulty line can be identified by detecting changes in ground potential across each phase in the IT system. IT systems have a characteristic in which the potential of each phase changes when a grounding system fault occurs. Technologies are being developed to leverage this characteristic to detect grounding system abnormalities or identify faulty lines. In IT systems, when a ground fault occurs on a specific line, the ground potential of the phase with the grounding fault decreases, while the potential of the healthy phase without the fault increases. Therefore, the faulty line can be identified by detecting the difference in ground potential across each phase.

[0005] Another approach is being developed: connecting an insulation monitoring device with a high impedance between the power system and the ground, and measuring the current from the closed circuit formed between the power system and the ground when a grounding system fault occurs in a specific area. In this method, the current flowing through the insulation monitoring device can be detected by the voltage distribution ratio caused by the internal resistance of the insulation monitoring device. The insulation monitoring device can further facilitate the detection of circulating current in the closed circuit by injecting a specific signal, such as a square wave, between the power line and the ground.

[0006] However, the method of detecting a change in voltage or the amount of current circulating in a closed circuit has the problem of making it difficult to detect and respond to a fault in the grounding system in a phase-balanced state. Phase-balanced leakage current refers to a situation in which each phase electrically leaks through an impedance value almost identical to the ground, such as when all power lines in the system are submerged. If a human body touches a specific phase in a phase-balanced leakage current situation, an electric shock accident may occur due to the reduced system grounding resistance (hundreds of ohms). Moreover, in the event of such an electric shock accident, since there is no difference in the outflow and inflow current of the leakage circuit breaker, a fault in the ZCT inside the leakage circuit breaker is not detected, and there is a risk that a continuous electric shock may occur without the circuit breaker tripping.

[0007] In the case of a phase-balanced leakage current, each phase of the power system reaches a state of equilibrium, and a stable state with no voltage fluctuations is achieved. Furthermore, the fault current circulating in the closed circuit between the power system and the ground flows in a small amount that is difficult to measure due to phase-balanced leakage current. In other words, when a phase-balanced leakage current occurs, the electrical state is very similar to the normal state in which no grounding system fault has occurred. For this reason, methods that detect voltage changes or measure the amount of fault current circulating in the closed circuit present difficulties in detecting the occurrence of a phase-balanced leakage current.

[0008] Meanwhile, capacitive leakage current exists due to electrostatic capacitance in many electrical devices. Since capacitive leakage current is less likely to pose a risk than resistive leakage current unless it is excessive, it is necessary to eliminate it when detecting leakage current and detect only resistive leakage current.

[0009] Conventional insulation monitoring devices measure only the resistive leakage current, excluding capacitance. This requires waiting until the ground capacitance of each line is fully buffered by the fault detection pulse. In other words, resistive leakage current is detected through the current flowing between the system and ground after the transient response is fully completed. However, detection delays of several seconds or even minutes may occur, depending on the system resistance and the ground capacitance of each line.

[0010] Furthermore, conventional insulation monitoring devices have a problem where, if the ground capacitance of each line distributed in the system is asymmetrical, the leakage current of the resistive component and the asymmetric capacitance component are combined and detected. While the actual insulation resistance value may be good, the asymmetric ground capacitance current distributed across each line may flow through the measurement resistance, leading to false detection of an insulation resistance problem.

[0011] Furthermore, to further limit system leakage current, the detection resistance within the insulation monitoring device could not be arbitrarily adjusted. Because detection is based on the current flowing through the detection resistance, increasing resistance lowers the current, requiring a more sensitive resolution.

[0012] Meanwhile, Korean Patent No. 10-2671336, published on June 3, 2024, relates to an "insulation monitoring device capable of measuring electrostatic capacity." The device is configured to quickly separate and measure electrostatic capacity and insulation resistance in the air while forming a ground and closed circuit when a ground fault current occurs, and to eliminate the risk of damage to the internal circuit of the insulation monitoring device even when a high-voltage voltage is applied between phases. An insulation monitoring device capable of measuring electrostatic capacity is disclosed, which includes a constant voltage / constant current generator that generates a measurement current (Im) as a constant current, a semiconductor switch (T1, T2) that is turned on by a start signal of an MCU so that the measurement current (Im) output from the constant voltage / constant current generator (100) is conducted to a power line for each phase, a current detection unit that detects the magnitude of the measurement current flowing through the insulation resistance (Rf) between the system and the ground after the capacitor between the system and the ground is fully charged due to the measurement current flowing in the power line energized by the semiconductor switch, and measures the insulation resistance (Rf), and a voltage detection unit that detects the charging voltage at both ends of the capacitor after the capacitor between the system and the ground is fully charged due to the measurement current flowing in the power line energized by the semiconductor switch, and measures the electrostatic capacity through pre-stored charging voltage and electrostatic capacity-related data.

[0013] [Prior Art Literature]

[0014] [Patent Document]

[0015] (Patent Document 1) KR 10-2671336 B1 (2024.06.03.)

[0016] One object of the present invention is to provide a simple leakage current detection device that can quickly and accurately detect leakage current in an IT system.

[0017] Another object of the present invention is to provide a leakage current detection device capable of filtering capacitive leakage current and detecting only resistive leakage current in an IT system.

[0018] Another object of the present invention is to provide a leakage current detection device capable of accurately detecting phase-balance resistive leakage current in an IT system.

[0019] Another object of the present invention is to provide a leakage detection device capable of quickly and accurately detecting the phase in which leakage current occurs when a phase-balance resistive leakage current occurs in an IT system.

[0020] The problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0021] According to one aspect of the proposed invention, a leakage current detection device (100, 200, 1300, 1400, 1500, 1600, 1700) used in an IT system includes an offset generation unit (150, 250, 1350) and an amplifier unit (160, 260, 1360).

[0022] A leakage current detection device (100, 200, 1300, 1400, 1500, 1600, 1700) is connected to a neutral point (C) of a secondary power line (L1, L2; L1, L2, L3) to which a load is connected and is separated from the primary power distribution line by an insulator (110, 210, 1310, 1410, 1510, 1610, 1710). The insulator (110, 210, 1310, 1410, 1510, 1610, 1710) separates the primary power distribution line from the secondary IT system power line (L1, L2; L1, L2, L3).

[0023] The offset generating unit (150, 250, 1350) is connected at one end to the secondary neutral point (C) of the insulating unit (110, 210, 1310, 1410, 1510, 1610, 1710) and applies a DC offset voltage to the secondary neutral point (C). The offset generating unit (150, 250, 1350) can set the voltage of the secondary neutral point (C) to be higher than the voltage of the other end (D) toward ground.

[0024] The amplifier (160, 260, 1360) is connected between the offset generator (150, 250, 1350) and the ground, and receives and amplifies the voltage of the other end (D) of the offset generator (150, 250, 1350) toward the ground. The amplifier (160, 260, 1360) can have a gain set to be less than or equal to 1 so that the output voltage is lower than the input voltage.

[0025] The above amplifier unit (160, 260, 1360) includes a first amplifier unit (161, 261, 1361) and a second amplifier unit (162, 262, 1362). The first amplifier unit (161, 261, 1361) receives the voltage of the other end (D) of the offset generator unit (150, 250, 1350) and amplifies it. The second amplifier unit (162, 262, 1362) outputs a waveform that is inverted from the output of the first amplifier unit (161, 261, 1361). For example, the first amplifier unit (161, 261, 1361) and the second amplifier unit (162, 262, 1362) can be configured as an inverting amplifier.

[0026] According to an additional aspect, the second amplifier unit (162, 262, 1362) may be configured to receive the output voltage of the first amplifier unit (161, 261, 1361) as input and output an inverted waveform. For example, the amplifier unit (160, 260, 1360) may be configured to include a first amplifier unit (161, 261, 1361) configured as an inverting amplifier and a second amplifier unit (162, 262, 1362) configured as a cascaded inverting amplifier.

[0027] According to an additional aspect, the leakage detection device (100, 200, 1300, 1400, 1500, 1600, 1700) further includes a peak detection unit (170, 270, 1370). The peak detection unit (170, 270, 1370) outputs a signal corresponding to the maximum value of the output waveform of the amplifier unit (160, 260, 1360).

[0028] According to a variation of the embodiment, the peak detection unit (170, 270, 1370) includes a first peak detection unit (271) and a second peak detection unit (272), and outputs a signal corresponding to the maximum value of the output waveform of the first amplifier unit (161, 261, 1361) and a signal corresponding to the maximum value of the output waveform of the second amplifier unit (162, 262, 1362), respectively. That is, the first peak detection unit (271) can be configured to output a signal corresponding to the maximum value of the output waveform of the first amplifier unit (161, 261, 1361), and the second peak detection unit (272) can be configured to output a signal corresponding to the maximum value of the output waveform of the second amplifier unit (162, 262, 1362), respectively.

[0029] According to an additional aspect, the peak detection unit (170, 270, 1370) may be configured to include a rectifier circuit. The rectifier circuit of the peak detection unit (170, 270, 1370) may be configured to include a diode placed between the input and the output and a capacitor placed between the output and the ground.

[0030] According to an additional aspect, the leakage detection device (100, 200, 1300, 1400, 1500, 1600, 1700) further includes a differential comparison unit (180, 280, 1380). The differential comparison unit (180, 280, 1380) outputs a signal including a DC offset voltage based on the output of the first amplifier unit (161, 261, 1361) and the output of the second amplifier unit (162, 262, 1362).

[0031] For example, the differential comparison unit (180, 280, 1380) can directly receive the output of the amplifier unit (160, 260, 1360) and output a signal including a DC offset voltage from the output of the first amplifier unit (161, 261, 1361) and the output of the second amplifier unit (162, 262, 1362).

[0032] According to a variation of the embodiment, the differential comparison unit (180, 280, 1380) may receive the output of the peak detection unit (170, 270, 1370) and output a signal including a DC offset voltage. For example, a signal including a DC offset voltage may be output from the output of the first peak detection unit (271) corresponding to the output of the first amplifier unit (161, 261, 1361) and the output of the second peak detection unit (272) corresponding to the output of the second amplifier unit (162, 262, 1362).

[0033] For example, when the amplifier (160, 260, 1360), the peak detection unit (170, 270, 1370), and the differential comparison unit (180, 280, 1380) are connected in series, the signal output from the amplifier (160, 260, 1360) is transmitted to the differential comparison unit (180, 280, 1380) through the peak detection unit (170, 270, 1370). In this case, the differential comparison unit (180, 280, 1380) can output a signal including a DC offset voltage by using a signal transmitted through a peak detection unit (170, 270, 1370) based on the output of the first amplifier unit (161, 261, 1361) and the output of the second amplifier unit (162, 262, 1362).

[0034] According to an additional aspect, the differential comparison unit (180, 280, 1380) may be configured as a differential amplifier circuit including an operational amplifier.

[0035] According to a variation of the embodiment, the differential comparison unit (180, 280, 1380) may further include a comparator (not shown). For example, by inputting the output of the differential amplifier circuit to a comparator to which a reference voltage is input, a signal for simply determining resistive leakage current can be output based on the difference from the reference voltage.

[0036] According to an additional aspect, the leakage detection device (100, 200, 1300, 1400, 1500, 1600, 1700) further includes a control unit (190, 290, 1390, 1490, 1590, 1690, 1790). The control unit (190, 290, 1390, 1490, 1590, 1690, 1790) determines that a resistive leakage has occurred when there is a difference in the output values ​​of the first amplifier unit (161, 261, 1361) and the second amplifier unit (162, 262, 1362) based on the output signal of the amplifier unit (160, 260, 1360).

[0037] According to a variation of the embodiment, the control unit (190, 290, 1390, 1490, 1590, 1690, 1790) can determine the occurrence of resistive leakage current using the output of the peak detection unit (170, 270, 1370). Since the peak detection unit (170, 270, 1370) outputs a signal corresponding to the maximum value of the output waveform of the amplifier unit (160, 260, 1360), the control unit (190, 290, 1390, 1490, 1590, 1690, 1790) can determine the occurrence of resistive leakage current based on the output signal of the amplifier unit (160, 260, 1360).

[0038] According to another variation of the embodiment, the control unit (190, 290, 1390, 1490, 1590, 1690, 1790) can determine the occurrence of resistive leakage current using the output of the differential comparison unit (180, 280, 1380). Since the output of the differential comparison unit (180, 280, 1380) is also obtained based on the output of the amplifier unit (160, 260, 1360), the control unit (190, 290, 1390, 1490, 1590, 1690, 1790) can determine the occurrence of resistive leakage current based on the output signal of the amplifier unit (160, 260, 1360).

[0039] According to another variation of the embodiment, the control unit (190, 290, 1390, 1490, 1590, 1690, 1790) can determine the occurrence of a resistive leakage current based on a signal generated when the output of the amplifier unit (160, 260, 1360) passes through the peak detection unit (170, 270, 1370) and the differential comparison unit (180, 280, 1380).

[0040] According to an additional aspect, the leakage detection device (100, 200, 1300, 1400, 1500, 1600, 1700) can be set to operate in an alarm mode or a blocking mode.

[0041] According to an additional aspect, the control unit (190, 290, 1390, 1490, 1590, 1690, 1790) may be configured to output an alarm signal notifying the occurrence of a resistive leakage current in the case of an alarm mode when a resistive leakage current occurs, and to transmit a signal to a circuit breaker (not shown) to cut off the secondary power lines (L1, L2; L1, L2, L3) to which a load is connected by the insulating unit (110, 210, 1310, 1410, 1510, 1610, 1710) in the case of a blocking mode.

[0042] According to an additional aspect, the control unit (190, 290, 1390, 1490, 1590, 1690, 1790) determines that a resistive leakage current other than a phase-balanced current has occurred when the output of the amplifier unit (160, 260, 1360) is an AC signal including a DC offset, and determines that a phase-balanced resistive leakage current has occurred when the output of the amplifier unit (160, 260, 1360) is a DC signal including a DC offset.

[0043] According to an additional aspect, the control unit (190, 290, 1390, 1490, 1590, 1690, 1790) includes an AD converter unit (295) that generates a digital signal based on an analog signal output from the amplifier unit (160, 260, 1360). The control unit (190, 290, 1390, 1490, 1590, 1690, 1790) can determine whether the output waveform of the amplifier unit (160, 260, 1360) is direct current or alternating current through the AD converter unit (295).

[0044] According to an additional aspect, the leakage detection device (100, 200, 1300, 1400, 1500, 1600, 1700) further includes a circuit that transmits the output of the amplifier unit (160, 260, 1360) to the AD converter unit (295). For example, the output of the amplifier unit (160, 260, 1360) can be transmitted to the AD converter unit (295) through the differential amplifier circuit (285).

[0045] According to an additional aspect, the control unit (190, 290, 1390, 1490, 1590, 1690, 1790) determines whether the resistive leakage is a phase-balance resistive leakage only when it is determined that a resistive leakage has occurred based on the output of the amplifier unit (160, 260, 1360).

[0046] According to a variation of the embodiment, only when the signal (T) input to the control unit (190, 290, 1390, 1490, 1590, 1690, 1790) is a signal corresponding to the occurrence of resistive leakage, the AD converter unit (295) may be configured to operate to determine whether the resistive leakage is a phase-equilibrium storage leakage. If no resistive leakage occurs, the operation of the AD converter unit (295) may be stopped to efficiently use power.

[0047] According to an additional aspect, the leakage detection device (100, 200, 1300, 1400, 1500, 1600, 1700) further includes a plurality of voltage regulation units (1451, 1452; 1551, 1552; 1650) and a plurality of phase discrimination peak detection units (1461, 1462; 1561, 1562; 1660).

[0048] Each voltage regulator (1451, 1452; 1551, 1552; 1650) has one end connected to the secondary power line (L1, L2; L1, L2, L3) of the insulating part (110, 210, 1310, 1410, 1510, 1610, 1710), and the other end connected to ground, and outputs a peak-to-peak voltage signal that is smaller than the peak-to-peak voltage of the power line (L1, L2; L1, L2, L3).

[0049] Each of the peak detection units (1461, 1462; 1561, 1562; 1660) for each phase is connected to each of the plurality of voltage control units (1451, 1452; 1551, 1552; 1650), and outputs a signal corresponding to the maximum value of the signal waveform output from each of the voltage control units (1451, 1452; 1551, 1552; 1650).

[0050] According to an additional aspect, the peak detection unit (1461, 1462; 1561, 1562; 1660) for phase discrimination may be configured to include a rectifier circuit. The rectifier circuit of the peak detection unit (1461, 1462; 1561, 1562; 1660) for phase discrimination may be configured to include a diode arranged between the input and the output and a capacitor arranged between the output and the ground.

[0051] According to an additional aspect, the peak detection unit (1461, 1462; 1561, 1562; 1660) for phase discrimination includes an operational amplifier to which the output of the voltage control unit (1451, 1452; 1551, 1552; 1650) is input as a positive input and which has a feedback loop between the output and the negative input. For example, the peak detection unit (1461, 1462; 1561, 1562; 1660) for phase discrimination can be configured to include a non-inverting amplifier or a buffer. Unlike a configuration having a negative input feedback loop such as an inverting amplifier, this configuration can detect while maintaining insulation because the input current does not flow through the feedback loop. This configuration can obtain superior insulation performance compared to a typical inverting amplifier.

[0052] According to an additional aspect, when a resistive leakage current occurs, the control unit (190, 290, 1390, 1490, 1590, 1690, 1790) can determine in which power line the leakage current occurred based on the signal of the peak detection unit (1461, 1462; 1561, 1562; 1660) for phase discrimination.

[0053] According to an additional aspect, the leakage detection device (100, 200, 1300, 1400, 1500, 1600, 1700) further includes a potential comparison unit (1470, 1570, 1670).

[0054] The potential comparison unit (1470, 1570, 1670) receives two outputs from among the outputs of the plurality of phase discrimination peak detection units (1461, 1462; 1561, 1562; 1660) and outputs a binary signal. By using the binary signal, the control unit can process the signal more efficiently. In addition, the sensitivity of the difference value that serves as the standard for phase discrimination can be adjusted by adjusting the resistance of the differential amplifier constituting the potential comparison unit (1470, 1570, 1670).

[0055] According to an additional aspect, the potential comparison unit (1470, 1570, 1670) may be configured to include a first differential amplifier (1571) and a second differential amplifier (1572) whose inputs are crossed with each other. A binary signal can be output using a pair of differential amplifiers whose inputs are crossed with each other.

[0056] The first differential amplifier (1571) is configured to receive the first output, which is one output among the plurality of peak detection units for phase discrimination (1461, 1462; 1561, 1562; 1660), as a positive input, and to receive the second output, which is the other output, as a negative input.

[0057] The second differential amplifier (1572) is configured to receive the first output as a negative input and the second output as a positive input so that the input signals of the first differential amplifier (1571) are input in a crossed manner.

[0058] According to an additional aspect, the leakage detection device (100, 200, 1300, 1400, 1500, 1600, 1700) further includes a switch (SW1, SW2) arranged between the secondary power lines (L1, L2; L1, L2, L3) of the insulating part (110, 210, 1310, 1410, 1510, 1610, 1710) and the voltage control part (1451, 1452; 1551, 1552; 1650).

[0059] According to an additional aspect, when a resistive leakage current occurs, the control unit (190, 290, 1390, 1490, 1590, 1690, 1790) can operate the phase discrimination peak detection unit (1461, 1462; 1561, 1562; 1660) by connecting the switches (SW1, SW2), and can determine in which power line the leakage current occurred based on the signal of the phase discrimination peak detection unit (1461, 1462; 1561, 1562; 1660). When the switches (SW1, SW2) are used, the phase discrimination peak detection unit (1461, 1462; 1561, 1562; 1660) is operated only when a resistive leakage current occurs, thereby enabling efficient operation.

[0060] According to an additional aspect, the leakage current detection device (100, 200, 1300, 1400, 1500, 1600, 1700) further includes a test resistor (Rt1, Rt2) and a voltage detector (1781, 1782). The test resistor (Rt1, Rt2) is connected between the secondary power lines (L1, L2; L1, L2, L3) of the insulating part (110, 210, 1310, 1410, 1510, 1610, 1710) and ground by a switch (SWt1, SWt2). The voltage detector (1781, 1782) is connected between the test resistor (Rt1, Rt2) and ground.

[0061] According to an additional aspect, when the voltage received from the voltage detector (1781, 1782) is higher than the reference voltage, the control unit (190, 290, 1390, 1490, 1590, 1690, 1790) changes to a blocking mode that blocks the secondary power lines (L1, L2; L1, L2, L3) of the insulating unit (110, 210, 1310, 1410, 1510, 1610, 1710) when a resistive leakage current occurs.

[0062] According to an additional aspect, the leakage detection device (100, 200, 1300, 1400, 1500, 1600, 1700) further includes a blocking mode indicator (1797). The blocking mode indicator (1797) can externally notify that the operation mode has been changed to the blocking mode.

[0063] According to another aspect of the proposed invention, a leakage current detection method used in an IT system includes an offset voltage application step (S1910), a voltage input step (S1920), and an amplified waveform output step (S1930).

[0064] In the offset voltage application step (S1910), the offset generation unit (150, 250, 1350) applies a DC offset voltage to the secondary neutral point (C) of the insulation unit (110, 210, 1310, 1410, 1510, 1610, 1710) that separates the primary power distribution line from the secondary power line (L1, L2; L1, L2, L3).

[0065] In the voltage input stage (S1920), the amplifier section (160, 260, 1360) receives the voltage of the terminal (D) toward the ground of the offset generator section (150, 250, 1350) that applies a DC offset voltage to the secondary neutral point of the insulation section.

[0066] In the amplification waveform output stage (S1930), the amplifier unit (160, 260, 1360) amplifies the voltage of the terminal (D) toward the ground of the input offset generator unit (150, 250, 1350) through the first amplifier unit (161, 261, 1361) and outputs the amplified voltage, and outputs a waveform that is inverted from the output of the first amplifier unit (161, 261, 1361) through the second amplifier unit (162, 262, 1362).

[0067] According to an additional aspect, in the amplification waveform output step (S1930), the amplification unit (160, 260, 1360) transmits the output voltage of the first amplification unit (161, 261, 1361) to the input of the second amplification unit (162, 262, 1362). That is, the first amplification unit (161, 261, 1361) transmits the output voltage to the input of the second amplification unit (162, 262, 1362).

[0068] According to an additional aspect, the leakage current detection method further includes a peak detection step (S1940). In the peak detection step (S1940), the peak detection unit (170, 270, 1370) receives the output waveform of the first amplifier unit (161, 261, 1361) and the output waveform of the second amplifier unit (162, 262, 1362) and outputs a signal corresponding to each maximum value. The peak detection unit (170, 270, 1370) can rectify the input signal and output a signal corresponding to each maximum value.

[0069] According to an additional aspect, the leakage detection method further includes a differential comparison step (S1950). In the differential comparison step (S1950), the differential comparison unit (180, 280, 1380) outputs a signal including a DC offset voltage based on the output of the first amplifier unit (161, 261, 1361) and the output of the second amplifier unit (162, 262, 1362).

[0070] According to a variation of the embodiment, the differential comparison unit (180, 280, 1380) can receive a signal corresponding to the maximum value of the output waveform of the first amplifier unit (161, 261, 1361) output from the peak detection unit (170, 270, 1370) and a signal corresponding to the maximum value of the output waveform of the second amplifier unit (162, 262, 1362), and output a signal including a DC offset voltage.

[0071] According to an additional aspect, the leakage detection method further includes steps of determining a resistive leakage when there is a difference between two input values ​​in the differential comparison step (S1950) (S1960) and outputting a resistive leakage alarm (S1965).

[0072] According to an additional aspect, the leakage detection method further includes the steps of checking whether the current is in an alarm mode (S1970) if it is determined to be a resistive leakage, outputting a resistive leakage alarm signal if it is in an alarm mode (S1980), and outputting a signal to cut off the power line with a circuit breaker (not shown) if it is in a cutoff mode (S1990).

[0073] According to an additional aspect, the above leakage detection method further includes a voltage control step (S2020) and a peak detection step for phase discrimination (S2030).

[0074] In the voltage regulation step (S2020), the voltage regulation unit (1451, 1452; 1551, 1552; 1650) lowers the peak-to-peak voltage of the voltage signal of the secondary power lines (L1, L2; L1, L2, L3) of the insulating unit (110, 210, 1310, 1410, 1510, 1610, 1710) to output a regulated voltage.

[0075] In the peak detection step for upper discrimination (S2030), the peak detection unit for upper discrimination (1461, 1462; 1561, 1562; 1660) outputs a peak signal for upper discrimination corresponding to the maximum value of the adjusted voltage waveform.

[0076] According to an additional aspect, the above leakage detection method further includes a potential comparison step (S2040).

[0077] In the potential comparison step (S2040), the potential comparison unit (1470, 1670) receives two signals among multiple peak signals for phase discrimination and outputs a binary signal.

[0078] According to an additional aspect, the potential comparison step (S2040) includes a first differential amplification step and a second differential amplification step.

[0079] In the first differential amplification stage, the first differential amplifier (1571) receives the first signal among the two signals at the positive input, and receives the second signal among the two signals at the negative input.

[0080] In the second differential amplification stage, the second differential amplifier (1572) crosses the signal input to the first differential amplifier (1571), and receives the second signal at the positive input and the first signal at the negative input.

[0081] According to an additional aspect, the above leakage detection method further includes a step (S2050) of identifying a power line in which a leakage has occurred. The control unit (190, 290, 1390, 1490, 1590, 1690, 1790) can identify a power line in which a leakage has occurred using a binary signal output in the potential comparison step (S2040).

[0082] According to an additional aspect, the leakage detection method further includes the steps of connecting a test resistor between a power line and a ground, measuring a voltage from a voltage detector connected to the test resistor, setting the system to an alarm mode when the voltage measured for all power lines is less than a reference value, and setting the system to a blocking mode when the voltage measured for any one power line is greater than the reference value.

[0083] The leakage current detection device and method of an IT system according to the present invention can filter out capacitive leakage current using a DC offset voltage and detect only resistive leakage current.

[0084] The leakage current detection device and method of the IT system according to the present invention can accurately detect the phase-balance resistive leakage current, and thus can prevent damage to people due to leakage current even in cases such as power line flooding.

[0085] Furthermore, according to the present invention, leakage current can be detected quickly and accurately in an IT system, and it has a simple structure, making it easy to manufacture.

[0086] In addition, according to the present invention, when a phase-balanced resistive leakage current occurs in an IT system, the phase in which the leakage current occurs can be quickly and accurately detected.

[0087] Fig. 1 is a schematic diagram showing the main configuration of a leakage current detection device of an IT system according to one embodiment.

[0088] FIG. 2a is a circuit diagram specifically showing the main configuration of a leakage current detection device of an IT system according to one embodiment.

[0089] FIG. 2b, FIG. 2c, FIG. 2d, FIG. 2e, and FIG. 2f are circuit diagrams each specifically showing the main configuration of a leakage current detection device of an IT system according to a modification of one embodiment.

[0090] Fig. 3 is a photograph showing the main components of a leakage current detection device of an IT system according to one embodiment implemented as an actual circuit.

[0091] FIG. 4a and FIG. 4b are simulation result screens showing the input and output of the amplifier when the leakage detection device of the IT system according to one embodiment is in a normal state.

[0092] Fig. 5 is a circuit diagram showing a case where a resistive leakage current occurs in a leakage current detection device of an IT system according to one embodiment.

[0093] FIG. 6a and FIG. 6b are simulation result screens showing the input and output of an amplifier section when a resistive leakage current occurs in a leakage current detection device of an IT system according to one embodiment.

[0094] Fig. 7 is a circuit diagram showing a case where a phase-balance resistive leakage current occurs in a leakage current detection device of an IT system according to one embodiment.

[0095] FIG. 8a and FIG. 8b are simulation result screens showing the input and output of an amplifier section when a phase-balance resistive leakage current occurs in a leakage current detection device of an IT system according to one embodiment.

[0096] Fig. 9 is a circuit diagram showing a case where capacitive leakage occurs in a leakage detection device of an IT system according to one embodiment.

[0097] FIG. 10a and FIG. 10b are simulation result screens showing the input and output of an amplifier section when capacitive leakage occurs in a leakage detection device of an IT system according to one embodiment.

[0098] Fig. 11 is a circuit diagram showing a case where a phase-balanced capacitive leakage current occurs in a leakage current detection device of an IT system according to one embodiment.

[0099] FIG. 12a and FIG. 12b are simulation result screens showing the input and output of an amplifier section when a phase-balanced capacitive leakage current occurs in a leakage current detection device of an IT system according to one embodiment.

[0100] Figure 13a is a schematic diagram showing a case where a leakage detection device of an IT system according to one embodiment is applied to a three-phase power supply.

[0101] Figure 13b is a schematic diagram showing a case where a leakage detection device of an IT system according to a variation of one embodiment is applied to a three-phase power supply.

[0102] Fig. 14 is a schematic diagram showing the main configuration of a leakage detection device of an IT system according to one embodiment, when the device includes a leakage phase determination unit.

[0103] FIG. 15a is a circuit diagram specifically showing the main configuration of a leakage detection device of an IT system according to one embodiment, in which a leakage phase determination unit is included.

[0104] FIG. 15b is a circuit diagram specifically showing the main configuration of a leakage detection device of an IT system according to a variation of one embodiment, in which a leakage phase determination unit is included.

[0105] Fig. 16 is a schematic diagram showing the main configuration of a leakage detection device of an IT system according to one embodiment, which includes a leakage phase determination unit, when applied to a three-phase power supply.

[0106] Fig. 17 is a schematic diagram showing the configuration of a capacitive leakage current detection unit in a leakage current detection device of an IT system according to one embodiment.

[0107] Fig. 18 is a flowchart showing a method for determining an operation mode using a capacitive leakage current detection unit in a leakage current detection device of an IT system according to one embodiment.

[0108] Fig. 19 is a flowchart showing a method for detecting a leakage state using a leakage detector in a leakage detection device of an IT system according to one embodiment.

[0109] Fig. 20 is a flowchart showing a method for identifying a power line in which a leakage current has occurred using a leakage current detector in a leakage current detection device of an IT system according to one embodiment.

[0110] The aforementioned and additional aspects are embodied in embodiments described with reference to the attached drawings. It is understood that the components of each embodiment can be combined in various ways within the embodiment or with components of other embodiments, as long as there is no other mention or inconsistency between them. Based on the principle that an inventor can appropriately define the concept of a term to best describe his or her invention, the terms used in this specification and claims should be interpreted as meanings and concepts consistent with the described content or proposed technical idea. A module or part in this specification may be a set of program instructions stored in a memory so that it can be executed by a computer or processor, or may be implemented using a set of electronic components or circuits such as an ASIC or FPGA so that such instructions can be executed. In addition, the operation of each module or part may be performed by one or more processors or devices. Components denoted by the same or similar symbols perform the same or similar functions, and thus, their descriptions may be omitted. For components with drawing symbols whose descriptions are omitted, reference may be made to the previously described description of the components with the same or similar symbols.

[0111] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[0112] Fig. 1 is a schematic diagram showing the main configuration of a leakage current detection device of an IT system according to one embodiment.

[0113] According to one aspect of the proposed invention, a leakage current detection device (100) used in an IT system includes a resistive leakage current detection unit (120). The leakage current detection device (100) may further include a control unit (190) that receives an output result of the resistive leakage current detection unit (120).

[0114] A leakage current detection device (100) is connected to the neutral point (C) of the secondary power lines (L1, L2) of the insulating section (110). The insulating section (110) separates the primary power distribution line from the secondary power lines (L1, L2) of the IT system. In the IT system, the secondary power lines (L1, L2) are ungrounded or high-resistance grounded.

[0115] The insulation section (110) is configured to convert from an existing power distribution line to an IT system. The power supplied to the power lines (L1, L2) on the secondary side of the insulation section (110) is supplied to the load (140). According to the law of conservation of energy and Kirchhoff's law, the current on the secondary side of the insulation section (110) cannot flow to the existing power distribution line on the primary side of the insulation section (110). This also applies when a fault occurs in the grounding system. The current flowing from the secondary side of the insulation section (110) to the ground cannot flow to the primary side of the insulation section (110), and this current forms a return path only to the secondary side of the insulation section (110).

[0116] The insulation unit (110) may be configured as an insulation transformer or generator capable of insulating the existing power distribution line. For example, the insulation transformer may be configured as a tap transformer.

[0117] The resistive leakage detection unit (120) includes an offset generation unit (150) and an amplifier unit (160). The resistive leakage detection unit (120) may further include a peak detection unit (170) and a differential comparison unit (180).

[0118] The offset generating unit (150) is connected at one end to the secondary neutral point (C) or neutral line of the insulating unit (110) and applies a DC offset voltage to the secondary neutral point (C) and the power lines (L1, L2). The other end (D) of the offset generating unit (150) is connected to the ground through the amplifier unit (160). The offset generating unit (150) can be configured using a DC power supply, a battery, a current transformer, etc. For example, the offset generating unit (150) can be configured using a DC voltage by an analog rectifier circuit or a DC voltage by an SMPS, or using a current transformer that can change the voltage according to the output resistance value.

[0119] When a DC offset voltage is output from the offset generating unit (150), the voltage of the secondary neutral point (C) of the insulating unit (110) rises by the DC offset voltage compared to the other end (D) on the ground side. Similarly, the voltage of the secondary power lines (L1, L2) of the insulating unit (110) also rises by the DC offset voltage compared to before the output of the offset generating unit (150) is input.

[0120] According to an additional aspect, the offset generating unit (150) can set the voltage of the secondary neutral point (C) higher than the voltage of the other end (D) facing the ground. That is, the DC offset voltage can be set to a positive (+) value. In this case, the positive pole of the offset generating unit (150) is connected to the neutral point (C) of the secondary power line of the insulation unit (110), and the negative pole is connected to the amplifier unit (160).

[0121] According to a variation of the embodiment, the offset generator (150) can set the voltage of the secondary neutral point (C) lower than the voltage of the other end (D) toward the ground. That is, the DC offset voltage can be set to a negative (-) value. In this case, unlike the previous example, the polarity of the offset generator (150) can be reversed so that the positive pole is connected to the amplifier (160) and the negative pole is connected to the neutral point (C) of the secondary power line of the insulation unit (110). In this case, the voltage of the secondary neutral point (C) of the insulation unit (110) drops by the DC offset voltage compared to the other end (D) toward the ground. Similarly, the voltage of the secondary power lines (L1, L2) of the insulation unit (110) also drops by the DC offset voltage compared to before the output of the offset generator (150) is input. When an insulation resistance failure occurs, a resistive leakage current can be detected using the same principle by detecting a change in the other end (D).

[0122] The amplifier (160) is connected between the offset generator (150) and the ground, and receives and amplifies the voltage of the other end (D) of the offset generator (150) toward the ground. The amplifier (160) can increase and output the input signal when the gain is greater than 1, output a signal of the same size as the input signal when the gain is 1, and reduce and output the input signal when the gain is less than 1. It is advantageous for the amplifier to have a large input resistance and a small output resistance. Therefore, it is preferable to configure the amplifier using an operational amplifier (OP amp).

[0123] The amplifier (160) includes a first amplifier (161) and a second amplifier (162). The first amplifier (161) receives the voltage of the low-voltage terminal (D), which is the other end of the offset generator (150), and outputs an amplified signal (S1). The second amplifier (162) outputs a waveform (S2) that is inverted from the output of the first amplifier (161). By using two waveforms that are inverted from each other, the offset voltage can be easily extracted from the input signal. For example, when a DC offset voltage is added to a voltage signal of a sine waveform, the first half-cycle voltage of the sine waveform (S1) output from the first amplifier (161) is obtained, and the second half-cycle voltage of the sine waveform (S2) output from the second amplifier (162) is obtained and compared, thereby easily confirming the DC offset voltage.

[0124] According to an additional aspect, at least one of the first amplifier unit (161) and the second amplifier unit (162) may be configured as a power operational amplifier (OP amp) having an output of 100 mA or more. Typically, when the output current of an operational amplifier (OP amp) is 100 mA or more, it can be classified as a power operational amplifier (OP amp). When configured as a power operational amplifier (OP amp), a smoother current supply is possible to the peak detection unit (170) at the rear end of the amplifier unit (160), and there is an advantage in that the charging inrush current of the smoothing capacitor used in the peak detection unit (170) can be charged more quickly. For example, when the output current of the power operational amplifier (OP amp) is 100 mA, the constant current charging time for charging 5 V to 220 uF is sufficient when about 11 ms. In this way, when the charging time of the smoothing capacitor is shortened, there is an effect of shortening the detection time of the resistive leakage current detection.

[0125] According to a variation of the embodiment, the second amplifier unit (162) can receive and amplify the voltage of the low-voltage terminal (D), which is the other end of the offset generator unit (150). In this case, when the first amplifier unit (161) is a buffer or a non-inverting amplifier, the second amplifier unit (161) is configured as an inverting amplifier. Meanwhile, when the first amplifier unit (161) is an inverting amplifier, the second amplifier unit (161) can be configured as a buffer or a non-inverting amplifier.

[0126] According to an additional aspect, the second amplifier unit (162) receives the output voltage (S1) of the first amplifier unit (161) as input and outputs an inverted waveform (S2). For example, the second amplifier unit (162) may be configured as an inverting amplifier that is cascaded to the output of the first amplifier unit (161). In this case, since the output of the second amplifier unit (162) is always inverted from the output of the first amplifier unit (161), the first amplifier unit (161) may be configured as an inverting amplifier as well as a buffer or a non-inverting amplifier.

[0127] According to an additional aspect, the leakage detection device (100) further includes a differential comparison unit (180). The differential comparison unit (180) receives the output (S1) of the first amplifier unit (161) and the output (S2) of the second amplifier unit (162) and outputs a signal including a DC offset voltage. The differential comparison unit (180) is configured to include a differential amplifier circuit, so as to compare whether there is a difference between the outputs of the two amplifier units, that is, the output (S1) of the first amplifier unit (161) and the output (S2) of the second amplifier unit (162). If there is a difference in the output values ​​of the two amplifier units, the differential comparison unit (180) can output a signal (T) to the control unit (190), so that the control unit (190) can generate an alarm or output a blocking signal.

[0128] According to an additional aspect, the leakage current detection device (100) further includes a peak detection unit (170). The peak detection unit (170) outputs a signal corresponding to the maximum value of the output waveform of the amplifier unit (160) so that the differential comparison unit (180) can easily compare the difference. For example, the peak detection unit (170) may be configured to include a rectifier circuit. The rectifier circuit may be configured using a diode and a capacitor. For example, the rectifier circuit may be configured by placing a diode between the input and output of the peak detection unit (170) and placing a smoothing capacitor between the output and ground. When an appropriate diode and smoothing capacitor are used, the rectifier circuit may convert and output signals (S1, S2) output from the first amplifier unit (161) and the second amplifier unit (162) into output waveforms (P1, P2) corresponding to a maximum value that generates less ripple and is close to the maximum value.

[0129] According to a variation of the embodiment, the peak detection unit (170) can be configured to output a signal corresponding to the maximum value of the output waveform of the first amplifier unit (161, 261, 1361) and a signal corresponding to the maximum value of the output waveform of the second amplifier unit (162, 262, 1362), respectively.

[0130] According to an additional aspect, the amplifier (160), the peak detection unit (170), and the differential comparison unit (180) can be connected in series. The differential comparison unit (180) receives a signal from the peak detection unit (170), and since the peak detection unit (170) outputs a signal corresponding to the maximum value of the output waveform of the amplifier (160), the differential comparison unit (180) can output a signal including a DC offset voltage based on the output of the amplifier (160).

[0131] According to an additional aspect, the leakage detection device (100) can be set to operate in an alarm mode or a blocking mode.

[0132] According to an additional aspect, the leakage current detection device (100) further includes a control unit (190). The control unit (190) receives an output signal (T) of a differential comparison unit (180), and determines that a resistive leakage current has occurred if there is a difference in the output values ​​of the two amplifier units (161, 162). If a resistive leakage current has occurred, the control unit (190) can be configured to output an alarm signal notifying the occurrence of a resistive leakage current in the case of an alarm mode, and to transmit a trip signal to a circuit breaker (not shown) to cut off the power line in the case of a cutoff mode.

[0133] FIG. 2a is a circuit diagram specifically showing the main configuration of a leakage current detection device of an IT system according to one embodiment.

[0134] Referring to Fig. 2a, the leakage detection device (200) includes an offset generation unit (250), an amplifier unit (260), a peak detection unit (270), and a differential comparison unit (280). The illustrated leakage detection device (200) is configured in the same manner as the resistive leakage detection unit (220). The leakage detection device (200) may further include a control unit (not shown).

[0135] The insulation unit (210) is composed of a transformer, and an offset generating unit (250) that generates a DC voltage is connected to the secondary neutral point (C) of the insulation unit (210).

[0136] A first amplifier unit (261) configured as an inverting amplifier and a second amplifier unit (262) configured as an inverting amplifier that takes the output of the first amplifier unit as input are connected to the other end (D) on the low voltage side of the offset generating unit (250). For example, the first amplifier unit (261) and the second amplifier unit (262) can be formed in a cascade structure. Both the first amplifier unit (261) and the second amplifier unit (262) can be formed using an operational amplifier (OP amp).

[0137] According to an additional aspect, the gain of the first amplifier unit (261) is set to be less than 1. If the gain of the first amplifier unit (261) is set to be less than 1, the voltage level processed in the subsequent stage is lowered, making it easier to process in the control unit. The gain of the second amplifier unit (262) can be set to be equal to 1. If the gain of the second amplifier unit (262) is set to 1, the output level of the first amplifier unit (261) and the output level of the second amplifier unit (262) become the same, making it easier to compare the output values ​​with each other.

[0138] The first amplifier unit (261) and the second amplifier unit (262) are supplied with a dual power supply to output signals. The dual power supply can be supplied by a separately provided dual power supply device (not shown). The dual power supply device has a positive output terminal (+Vcc), a negative output terminal (-Vcc), and a neutral point (GND) that can be grounded. The dual power supply device can be used as a power supply for electronic circuits other than the amplifier unit.

[0139] At least one of the first amplifier unit (261) and the second amplifier unit (262) is grounded to the ground by a positive power supply device. When the neutral point of the positive power supply device is connected to the ground, the positive and negative power supply terminals of each amplifier unit can be electrically connected to the corresponding ground. For example, the amplifier unit can be configured between the neutral point to which the offset generator unit is connected and the ground, so that it can be electrically grounded and form a path for leakage current to flow when a leakage current occurs. Meanwhile, by adjusting the resistance value of the amplifier unit, the amount of leakage current flowing to the ground when a leakage current occurs can be adjusted.

[0140] The output (S1) of the first amplifier (261) and the output (S2) of the second amplifier (262) are input to the peak detection unit (270). The peak detection unit (270) is composed of a rectifier circuit including a diode and a capacitor, and outputs rectified signals (P1, P2) corresponding to the maximum values ​​of the peaks from the input signals (S1, S2), respectively.

[0141] The differential comparison unit (280) receives signals (P1, P2) corresponding to the maximum values ​​of the signals (S1, S2) output from the first amplifier unit (161) and the second amplifier unit (162) output from the peak detection unit (270). The differential comparison unit (280) can compare the difference between the two input signals (P1, P2) to determine whether there is a DC offset voltage in the input signal and output the result as an output signal (T). The output signal (T) of the differential comparison unit (280) is transmitted to a control unit (not shown), and the control unit (not shown) can control power line cutoff by outputting a leakage alarm or a trip signal.

[0142] Referring to Fig. 2a, the differential comparison unit (280) is configured as a differential amplifier circuit including an operational amplifier. The differential comparison unit (280) receives the outputs (P1, P2) of the peak detection unit (270) and outputs a signal (T) including a DC offset voltage. Since the peak detection unit (270) receives the outputs (S1, S2) of the amplifier unit and outputs a signal (P1, P2) corresponding to the maximum value, the differential comparison unit (280) can be configured to output a signal (T) including a DC offset voltage based on the output of the amplifier unit (260).

[0143] According to a variation of the embodiment, the differential comparison unit (280) may be configured to further include a comparator (not shown). For example, the output of the differential amplifier circuit may be input to a comparator into which a reference voltage is input, so as to output a signal for simply determining resistive leakage current by the difference from the reference voltage. The reference voltage may be determined using the output of the voltage divider circuit. By configuring to select from a variable resistor or a plurality of resistors, the resistance value of the voltage divider circuit may be changed, so as to select a specific value from among various reference voltages.

[0144] According to an additional aspect, the leakage current detection device (200) further includes a control unit (290). The control unit (290) determines that a resistive leakage current has occurred when a difference between the output (S1) of the first amplifier unit (261) and the output (S2) of the second amplifier unit (262) is greater than a predetermined threshold value based on the output signals (S1, S2) of the amplifier unit (260).

[0145] FIG. 2b, FIG. 2c, FIG. 2d, FIG. 2e, and FIG. 2f are circuit diagrams each specifically showing the main configuration of a leakage current detection device of an IT system according to a modification of one embodiment.

[0146] Referring to FIG. 2b, the resistive leakage current detection unit (110) includes an offset generation unit (250), an amplifier unit (260), and a peak detection unit (270). The leakage current detection device (200) may further include a control unit (290).

[0147] Compared to Fig. 2a, the leakage detection device (200) of Fig. 2b does not include a differential comparison unit (280). Instead, the output (P1, P2) of the peak detection unit (270) is directly transmitted to the control unit (290). The control unit (290) can receive the signal of the peak detection unit (270) and perform various signal processing, such as analyzing the waveform of the input signal using an AD converter, etc.

[0148] According to a variation of the embodiment, the peak detection unit (270) includes a first peak detection unit (271) and a second peak detection unit (272). The first peak detection unit (271) can be configured to output a signal corresponding to the maximum value of the output waveform of the first amplifier unit (261), and the second peak detection unit (272) can be configured to output a signal corresponding to the maximum value of the output waveform of the second amplifier unit (262).

[0149] According to an additional aspect, the peak detection unit (270) may be configured to include a rectifier circuit. For example, the first peak detection unit (271) and the second peak detection unit (272) may be configured as rectifier circuits, each including a diode positioned between the input and the output and a capacitor positioned between the output and the ground.

[0150] The output signals (P1, P2) of the peak detection unit (270) are DC signals of the signals (S1, S2) output from the amplifier unit (260), so they are easy to process in the control unit. The control unit (290) can determine the occurrence of resistive leakage current using the output of the peak detection unit (270). Since the peak detection unit (270) outputs a signal corresponding to the maximum value of the output waveform of the amplifier unit (260), the control unit (290) can determine the occurrence of resistive leakage current based on the output signal of the amplifier unit (260).

[0151] Referring to FIG. 2c, the resistive leakage current detection unit (110) includes an offset generation unit (250) and an amplifier unit (260). The leakage current detection device (200) may further include a control unit (290).

[0152] Compared to Fig. 2b, the leakage detection device (200) of Fig. 2c does not include a peak detection unit (270). Instead, the output (S1, S2) of the amplifier unit (260) is directly transmitted to the control unit (290). The control unit (290) can receive the signal of the peak detection unit (270) and perform various signal processing, such as analyzing the waveform of the input signal using an AD converter, etc.

[0153] If the resistive leakage current detection unit (110) does not include the peak detection unit (270), the signal input to the microcontroller (MCU) may be a sine wave signal including a negative polarity. In this case, since the microcontroller (MCU) cannot receive a negative signal for signal processing, a typical DC level shifting circuit may be additionally configured. The entire waveform input to the microcontroller (MCU) may be shifted to a range that the microcontroller (MCU) can read. For example, when the presence or absence of an offset is detected by performing ADC processing on the waveform of the first amplifier (261), the entire waveform is shifted to a positive range, the average value for a specific cycle is obtained, and then the DC level shift value is subtracted to extract only the DC offset voltage. In addition to the average value, various calculation methods such as integration may be utilized to extract the DC offset.

[0154] Meanwhile, when only the S1 signal is used, it is difficult to determine whether the DC offset is superimposed by the offset generator (250) or is an unintended DC offset due to circuit noise, drift, etc. Therefore, when the S2 signal of the second amplifier (262) is detected simultaneously with S1, there is an advantage in that it can be determined that the signal superimposed on the first amplifier (261) and second amplifier (262) is a DC offset caused by the offset generator (250).

[0155] Referring to FIG. 2d, the first amplifier unit (265) and the second amplifier unit (266), which constitute the amplifier unit connected to the lower portion (D) of the offset generating unit (255), are connected in parallel.

[0156] The first amplifier unit (265) includes an inverting amplifier, and the second amplifier unit (266) is configured to include a non-inverting amplifier, so that outputs with opposite phases can be sent to the peak detection unit (270). In this case, the first amplifier unit (265), which is an inverting amplifier, can be grounded to the ground via a positive power supply. In addition to FIGS. 2A and 2B, various methods can be used to output signals with opposite phases, thereby easily detecting leakage current.

[0157] Referring to FIG. 2e, the resistive leakage current detection unit (110) includes an offset generation unit (250), an amplifier unit (260), and a differential comparison unit (285). The leakage current detection device (200) may further include a control unit (290).

[0158] Compared to Fig. 2a, the leakage current detection device (200) of Fig. 2e does not include a peak detection unit (270). Instead, the output (S1, S2) of the amplifier unit (260) is transmitted to the differential comparison unit (285), and the differential comparison unit (285) outputs a signal (T1) including a DC offset voltage and transmits it to the control unit (290).

[0159] The control unit (290) can receive a signal from the differential comparison unit (285) and perform various signal processing, such as analyzing the waveform of the input signal using an AD converter, etc.

[0160] According to another variation of the embodiment, the control unit (290) can determine the occurrence of resistive leakage current by using the output (T1) of the differential comparison unit (285). Since the output (T1) of the differential comparison unit (285) is also obtained based on the outputs (S1, S2) of the amplifier unit (260), the control unit (290) can determine the occurrence of resistive leakage current based on the output signals (S1, S2) of the amplifier unit (260).

[0161] Referring to FIG. 2f, the resistive leakage current detection unit (110) includes an offset generation unit (250), an amplifier unit (260), a peak detection unit (270), and a differential comparison unit (280) that receives the outputs (P1, P2) of the peak detection unit (270). The leakage current detection device (200) may further include a control unit (290) and a differential comparison unit (285) that receives the outputs (S1, S2) of the amplifier unit (260).

[0162] Compared to Fig. 2a, the leakage current detection device (200) of Fig. 2f further includes a differential comparison unit (285) that receives the outputs (S1, S2) of the control unit (290) and the amplifier unit (260).

[0163] As in Fig. 2a, the control unit (290) can determine whether a resistive leakage current has occurred by using the output (T) of the differential comparison unit (280) that receives the output (P1, P2) of the peak detection unit (270).

[0164] Meanwhile, the control unit (290) can receive the signal (T1) of the differential comparison unit (285) that receives the output (S1, S2) of the amplifier unit (260) and transmit it to the AD converter unit (295). The AD converter unit (295) of the control unit (290) can generate a digital signal based on the analog signal transmitted from the amplifier unit (260). The control unit (290) can determine whether the output waveform of the amplifier unit (260) is direct current or alternating current through the AD converter unit (295).

[0165] According to an additional aspect, the control unit (290) may be configured to determine that a non-phase-balanced resistive leakage current has occurred when the output of the amplifier unit (260) is an AC signal including a DC offset, and to determine that a phase-balanced resistive leakage current has occurred when the output of the amplifier unit (260) is a DC signal including a DC offset.

[0166] According to an additional aspect, the leakage detection device (200) further includes a circuit that transmits the output of the amplifier unit (260) to the AD converter unit (295). For example, the output of the amplifier unit (260) may be transmitted to the AD converter unit (295) through a differential amplifier circuit (285).

[0167] According to an additional aspect, the control unit (290) determines whether the resistive leakage is a phase-balanced resistive leakage only when it is determined that a resistive leakage has occurred based on the output of the amplifier unit (260).

[0168] For example, only when the signal (T) input to the control unit (290) is a signal corresponding to the occurrence of resistive leakage current, the AD converter unit (295) can be configured to operate to determine whether the resistive leakage current is a phase-balanced storage leakage current. If no resistive leakage current occurs, the operation of the AD converter unit (295) can be stopped to efficiently use power.

[0169] Fig. 3 is a photograph showing the main components of a leakage current detection device of an IT system according to one embodiment implemented as an actual circuit.

[0170] Referring to Fig. 3, the insulation section (310) of the leakage detection device is configured as a transformer. An offset generation section (350) that generates a DC voltage is connected to the secondary neutral point of the insulation section (310). An amplifier section (360) is configured to which a first amplifier section configured as an inverting amplifier and a second amplifier section configured as an inverting amplifier that takes as input the output of the first amplifier section are connected to the other end on the low voltage side of the offset generation section (350).

[0171] The output of the amplifier (360) is input to the peak detection unit and the differential comparison unit (380). The peak detection unit and the differential comparison unit (380) are configured as a rectifier circuit including a diode and a capacitor, and output a rectified signal corresponding to the maximum value of the peak from the output signal of the amplifier (360), and compare the difference between the two rectified signals to determine whether an offset voltage is included in the input signal, and output the result as an output signal (T). The output signal of the peak detection unit and the differential comparison unit (380) can be transmitted to a control unit including an MCU or the like to control a leakage alarm or a power line cutoff.

[0172] FIG. 4a and FIG. 4b are simulation result screens showing the input and output of the amplifier when the leakage detection device of the IT system according to one embodiment is in a normal state.

[0173] Fig. 4a is a graph showing a voltage signal of the other end (D) of the offset generating unit (250) of Fig. 2a, and Fig. 4b is a graph showing two voltage signals (P1, P2) which are outputs of the peak detection unit (270) of Fig. 2a.

[0174] In a normal state, the offset generating unit (250) does not form a circuit with the secondary power lines (L1, L2) of the insulator (210), so no current flows. Accordingly, one end (C) of the offset generating unit (250) increases the DC offset voltage on the secondary side of the insulator (210), but the other end (D) of the offset generating unit (250) is connected to ground. As a result, the voltage of the other end (D) of the offset generating unit (250) represents 0 V, which is a ground voltage, as shown in Fig. 4a.

[0175] Since the output of the first amplifier (261) also becomes 0 V, the output of the second amplifier (262) also becomes 0 V, and the output of the peak detection unit (270) becomes 0 V as shown in Fig. 4b.

[0176] Fig. 5 is a circuit diagram showing a case where a resistive leakage current occurs in a leakage current detection device of an IT system according to one embodiment.

[0177] Referring to Fig. 5, a case in which resistive leakage occurs in only one of the power lines (L1) is shown. When resistive leakage occurs, it can be seen that a leakage impedance or leakage resistance (R1) is connected between the power line (L1) and the ground (earth). A direct current and an alternating current circuit passing through the offset generation unit (550) is formed by the leakage resistance (R1). That is, the leakage current from the AC power line is transmitted to the ground through the leakage resistance (R1) and can flow back into the power system through the offset generation unit (550) connected to the ground.

[0178] FIG. 6a and FIG. 6b are simulation result screens showing the input and output of an amplifier section when a resistive leakage current occurs in a leakage current detection device of an IT system according to one embodiment.

[0179] FIG. 6a is a graph showing a voltage signal of the other end (D) of the offset generating unit (550) of FIG. 5, and FIG. 6b is a graph showing two voltage signals (P1, P2) which are outputs of the peak detection unit (570) of FIG. 5.

[0180] When a resistive leakage current occurs in only one (L1) of the power lines, a DC and AC signal are detected in the offset generating unit (550) by the current flowing to the offset generating unit (550) through the leakage resistor (R1). At this time, the voltage of the other end (D) of the offset generating unit (550) is lowered by the DC offset voltage compared to the neutral point (C) of the insulating unit (510), so that the voltage of the other end (D) of the offset generating unit (550) outputs an AC signal with a negative (-) offset, which is the ground voltage, as shown in Fig. 6a. That is, the positive (+) peak value of the sine waveform in Fig. 6a is output smaller than the negative (-) peak value.

[0181] The signal of Fig. 6a can be obtained as a first amplified signal (S1) and a second amplified signal (S2) which is an inverted version of the first amplified signal through the first amplifier unit (561) and the second amplifier unit (562). Fig. 6b shows output signals (P1, P2) obtained by rectifying this signal using a peak detector unit (570). Since both the first amplifier unit (561) and the second amplifier unit (562) are configured as inverting amplifiers, the red signal (P1) which inverts a relatively large negative peak value in Fig. 6a is outputted at a higher level than the blue signal (P2) which inverts a relatively small negative peak value.

[0182] Fig. 7 is a circuit diagram showing a case where a phase-balance resistive leakage current occurs in a leakage current detection device of an IT system according to one embodiment.

[0183] Referring to Figure 7, it shows a case where resistive leakage occurs in both power lines (L1, L2), such as in the case of flooding. In this case, it can be seen that a leakage impedance or leakage resistance (R1) is connected between one power line (L1) and the ground (earth), and a leakage impedance or leakage resistance (R2) is connected between the other power line (L2) and the ground (earth). When resistive leakage occurs due to the same cause, the leakage resistance (R1) and the leakage resistance (R2) can be seen to have the same value. This case is called resistive 'phase-balanced leakage'.

[0184] FIG. 8a and FIG. 8b are simulation result screens showing the input and output of an amplifier section when a phase-balance resistive leakage current occurs in a leakage current detection device of an IT system according to one embodiment.

[0185] Fig. 8a is a graph showing a voltage signal of the other end (D) of the offset generating unit (750) of Fig. 7, and Fig. 8b is a graph showing two voltage signals (P1, P2) which are outputs of the peak detection unit (770) of Fig. 7.

[0186] In the case of a resistive phase-balanced leakage current as in Fig. 7, the current flowing from one power line (L1) to the ground through the leakage resistor (R1) flows to another power line (L2) through another leakage resistor (R2) of the same size, so that the AC signal does not flow through the offset generating unit (750), and a negative DC voltage is output to the other end of the offset generating unit (750). At this time, since the secondary side of the insulating unit (710) is in phase balance, the voltage of the neutral point (C) becomes 0 V, and the other end (D) of the offset generating unit (750) exhibits a negative offset voltage as in Fig. 8a.

[0187] When the signal of Fig. 8a is inverted and amplified through the first amplifier (761), a positive DC signal (S1) is output, and when this is rectified, a DC signal (P1) indicated in red in Fig. 8b is output. When the positive DC signal (S1), which is the output of the first amplifier (761), is inverted and amplified through the second amplifier (762), a negative DC signal (S2) is output, but when this is rectified, 0 V is output because there is no positive signal, and this signal is indicated in blue in Fig. 8b.

[0188] Fig. 9 is a circuit diagram showing a case where capacitive leakage occurs in a leakage detection device of an IT system according to one embodiment.

[0189] Referring to Fig. 9, a case in which capacitive leakage current occurs in one of the power lines (L1) is shown. When capacitive leakage current occurs, it can be seen that leakage impedance or leakage capacitance (C1) is connected between the power line (L1) and the ground (earth). An AC circuit passing through the offset generating unit (950) is formed by the leakage capacitance (C1). That is, the leakage current from the AC power line is transmitted to the ground through the leakage capacitance (C1) and can flow back to the power line (L1) through the offset generating unit (950) connected to the ground. However, since a direct current signal cannot pass through the leakage capacitance (C1), only an AC signal can flow as the leakage current.

[0190] FIG. 10a and FIG. 10b are simulation result screens showing the input and output of an amplifier section when capacitive leakage occurs in a leakage detection device of an IT system according to one embodiment.

[0191] Fig. 10a is a graph showing a voltage signal of the other end (D) of the offset generating unit (950) of Fig. 9, and Fig. 10b is a graph showing two voltage signals (P1, P2) which are outputs of the peak detection unit (970) of Fig. 9.

[0192] When a capacitive leakage current occurs in only one of the power lines (L1), an AC signal is detected in the offset generating unit (550) by the current flowing to the offset generating unit (950) through the leakage capacitance (C1). Since the DC signal cannot pass through the leakage capacitance (C1), there is no DC offset, and thus the positive (+) peak value of the sine wave in Fig. 10a is output as the same as the negative (-) peak value.

[0193] Since the signal in Fig. 10a has the same positive (+) peak value and negative (-) peak value, the output signals (P1, P2) obtained by rectifying the signals amplified through the first amplifier (961) and the second amplifier (962) have the same values. This result is illustrated in Fig. 10b.

[0194] This invention can detect only resistive leakage current even if the ground capacitance value of each line is asymmetrically distributed only to one power line (L1).

[0195] Fig. 11 is a circuit diagram showing a case where a phase-balanced capacitive leakage current occurs in a leakage current detection device of an IT system according to one embodiment.

[0196] Referring to Fig. 11, it shows a case where capacitive leakage current occurs in both of the power lines (L1, L2). In this case, it can be seen that a leakage impedance or leakage capacitance (C1) is connected between one power line (L1) and the ground (earth), and a leakage impedance or leakage capacitance (C2) is connected between the other power line (L2) and the ground (earth). When capacitive leakage current occurs due to the same cause, the leakage capacitance (C1) and the leakage capacitance (C2) can be seen to have the same value. This case is called capacitive 'phase-balanced leakage current'.

[0197] FIG. 12a and FIG. 12b are simulation result screens showing the input and output of an amplifier section when a phase-balanced capacitive leakage current occurs in a leakage current detection device of an IT system according to one embodiment.

[0198] Fig. 12a is a graph showing a voltage signal of the other end (D) of the offset generating unit (1150) of Fig. 11, and Fig. 12b is a graph showing two voltage signals (P1, P2) which are outputs of the peak detection unit (1170) of Fig. 11.

[0199] In the case of a capacitive phase-balanced leakage current as in Fig. 11, the current flowing from one power line (L1) to the ground through the leakage capacitance (C1) flows to the other power line (L2) through another leakage capacitance (C2) of the same size, so that the AC signal does not flow through the offset generating unit (1150), and thus a voltage of approximately 0 V is output to the other terminal of the offset generating unit (1150) similar to the normal state. At this time, since the DC current does not flow through the leakage capacitances (C1, C2), the voltage at the other terminal (D) of the offset generating unit (1150) as in the normal state represents 0 V, which is the ground voltage, as in Fig. 12a.

[0200] As in the normal state, the output of the first amplifier (1161) and the output of the second amplifier (1162) also become 0 V, so that the output of the peak detection unit (1170) becomes 0 V as shown in Fig. 12b.

[0201] To summarize the results of FIGS. 4a to 12b, the output of the other end (D), which is the low-voltage part of the offset generating unit (250), shows 0 V, AC signal + DC offset, DC offset, AC signal, and 0 V in the normal state, resistive leakage current, resistive phase-balanced leakage current, capacitive leakage current, and capacitive phase-balanced leakage current, respectively. Therefore, when a DC offset is included in the output of the offset generating unit (250) or the output of the first amplifier unit (161), it can be determined that resistive leakage current has occurred. In most cases, since the impact of capacitive leakage current on the human body is small, the control unit (190) can perform a blocking operation or an alarm operation only in the case of resistive leakage current, not capacitive leakage current, by using the output of the offset generating unit (250) or the first amplifier unit (261).

[0202] In the conventional electrical and electronic fields, RC-based filters such as low-pass filters and integrators are sometimes used to detect voltages of a specific frequency. However, the detection time of these filters is affected by the time constant. Among these, the charging time constant is a very important factor in fault detection. How quickly a fault can be detected after it occurs is important. However, in these time constant-based filters, the detection sensitivity of DC offset voltage increases as the cutoff frequency is lowered, but the charging time constant increases, which increases the detection time. For example, when using a low-pass filter, if the cutoff frequency is set to 0.1 Hz to detect a DC offset, the charging time constant at this time takes approximately 1.6 seconds.

[0203] In contrast, the amplifier unit (160, 260) of this invention can detect insulation resistance failures more quickly without considering the time delay of the charging time constant. That is, while the conventional detection method is a frequency-based filter-based method, this invention is a faster and simpler detection method through comparison of the symmetry of a single waveform.

[0204] Meanwhile, the two outputs (P1, P2) of the peak detection unit (270) indicate (0V, 0V), (two different positive voltages), (one positive voltage and 0V), (the same positive voltage), (0V, 0V) in the normal state, resistive leakage current, resistive phase equilibrium leakage current, capacitive leakage current, and capacitive phase equilibrium leakage current, respectively. Therefore, only when the two outputs (P1, P2) of the peak detection unit (270) are different, it can be determined that resistive leakage current has occurred. For example, the control unit can directly compare the two outputs (P1, P2) and determine that resistive leakage current has occurred when the voltages of the two outputs (P1, P2) are different. In addition, by adding a differential comparison unit (280), a signal (T) indicating that a resistive leakage current has occurred is output when the voltages of the two outputs (P1, P2) are different, so that a blocking operation or an alarm operation corresponding to a resistive leakage current can be performed without a control unit (190) or with only a simple control unit (190).

[0205] The output sensitivity of the signal (T) can be adjusted by adjusting the DC offset applied voltage and the output ratio of the differential amplifier circuit of the first amplifier unit (161, 261), the second amplifier unit (162, 262), or the differential comparison unit (180, 280). For example, the trigger sensitivity of the signal (T) can be set to various values, such as line insulation resistance of 1 M ohm or less, or 500 k ohm or less.

[0206] In addition, the presence or absence of resistive leakage can be detected simply and quickly by comparing the signal (T) with a specific reference value, and changes in insulation resistance can be easily detected by continuously ADC processing the output waveform of the signal (T). In addition, it is also possible to receive the presence or absence of the signal (T) to check for the presence or absence of resistive leakage, and then perform ADC processing on the output signal of the amplifier to detect it (see Fig. 2f).

[0207] Of course, only the configuration of the resistive leakage current detection unit (120) can quickly detect only resistive insulation failures while excluding electrostatic capacitance, but it is also easy to implement a monitoring circuit that detects continuous signal changes by utilizing the examples disclosed above.

[0208] According to another aspect of the proposed invention, a leakage current detection device used in an IT system includes an offset generation unit (150, 250), an amplifier unit (160, 260), and a control unit (190, 290). An insulation unit (110, 210) separates a primary power distribution line from a secondary IT system power line. One end of the offset generation unit (150, 250) is connected to a secondary neutral point (C) of the insulation unit (110, 210), and applies a DC offset voltage to the secondary neutral point (C). An amplifier unit (160, 260) is connected between the offset generation unit (150, 250) and ground, and receives and amplifies a voltage of the other end (D) of the offset generation unit (150, 250) toward ground. The control unit (190, 290) determines whether a resistive leakage current has occurred based on the signal output from the amplifier unit (160, 260).

[0209] The leakage current detection device may further include a peak detection unit (170, 270) and a differential comparison unit (180, 280). The amplifier unit (160, 260) may further include a first amplifier unit (161, 261) and a second amplifier unit (162, 262). With respect to the offset generation unit (150, 250), the amplifier unit (160, 260), the peak detection unit (170, 270), the differential comparison unit (180, 280), the control unit (190, 290), etc., reference may be made to the parts already described above.

[0210] According to an additional aspect, the control unit (190, 290) may determine that a resistive leakage current has occurred when the output of the amplifier unit (160, 260) is an AC signal including a DC offset, and may determine that a phase-balanced resistive leakage current has occurred when the output of the amplifier unit is a DC signal including a DC offset.

[0211] The DC signal including the DC offset of this invention does not only refer to the ideal DC whose magnitude and direction are completely constant over time. Even in the case of actual phase equilibrium, small-scale impedance differences between each phase may cause small-scale pulsations or sinusoidal waves to be superimposed based on the DC offset. Even if there is a slight magnitude fluctuation due to a small signal below a certain level, if the direction remains constant, it can be regarded as DC. However, cases where the direction of the signal reverses over time are not included in the concept of DC as referred to in this invention. In addition, the scope of the DC analysis of this invention can be determined flexibly according to a threshold set according to the characteristics of the circuit and the purpose of the analysis.

[0212] Figure 13a is a schematic diagram showing a case where a leakage detection device of an IT system according to one embodiment is applied to a three-phase power supply.

[0213] Referring to Fig. 13a, the insulation unit (1310) is composed of a three-phase transformer. The secondary side of the insulation unit (1310) is connected to a load (1340) via power lines (L1, L2, L3). The offset generating unit (1350) is connected to a neutral line (N) connected to the secondary neutral point of the insulation unit (1310).

[0214] The illustrated leakage current detection device (1300) is configured in the same manner as the resistive leakage current detection unit (1320). The leakage current detection device (1300) may further include a control unit (not shown).

[0215] A leakage current detection device (1300) for a three-phase power supply can be configured by combining an offset generation unit (1350), an amplifier unit (1360), a peak detection unit (1370), and a differential comparison unit (1380). Each component of the leakage current detection device (1300) for a three-phase power supply can be configured in the same manner as the corresponding components of the single-phase power supply described above.

[0216] Figure 13b is a schematic diagram showing a case where a leakage detection device of an IT system according to a variation of one embodiment is applied to a three-phase power supply.

[0217] Referring to Fig. 13b, the secondary of the insulation section (1315) is configured with a delta connection. In this case, the neutral line (N) can be connected to the offset generation section (1350) using a three-phase load section (1317) configured with a Y connection. The offset generation section (1350) is connected to the amplifier section (1360), and the remaining components can be configured in the same manner as described above.

[0218] Fig. 14 is a schematic diagram showing the main configuration of a leakage detection device of an IT system according to one embodiment, when the device includes a leakage phase determination unit.

[0219] According to an additional aspect, a leakage detection device (1400) used in an IT system includes a resistive leakage detection unit (1420), a leakage phase determination unit (1430), and a control unit (1490). The resistive leakage detection unit (1420) can be configured in the same manner as the resistive leakage detection unit (120, 220, 1320) of the leakage detection device (100, 200, 1300) described above.

[0220] Referring to Fig. 14, a resistive leakage detection unit (1420) is placed between the secondary neutral point (C) of the insulating unit (1410) and the ground, and transmits a signal (T) related to whether or not a resistive leakage occurs from the resistive leakage detection unit (1420) to the control unit (1490).

[0221] The leakage phase determination unit (1430) of the leakage detection device (1400) includes a voltage control unit (1450) and a peak detection unit (1460) for phase determination.

[0222] The voltage regulation unit (1450) includes a plurality of voltage regulation units (1451, 1452) each having one end connected to the secondary power line (L1, L2) of the insulation unit (1410) and the other end connected to ground.

[0223] In the case of a single phase, two voltage regulation units can be configured, and in the case of a three phase, three voltage regulation units can be configured. For example, since Fig. 14 is a single phase, it can be configured to include two voltage regulation units: a first voltage regulation unit (1451) connected to a first power line (L1) and a second voltage regulation unit (1452) connected to a second power line (L2).

[0224] Each voltage regulator (1451, 1452) may be configured to output a peak-to-peak voltage signal that is smaller than the peak-to-peak voltage of the secondary power lines (L1, L2). Each voltage regulator (1451, 1452) may be configured as a voltage distribution circuit using a resistor.

[0225] The peak detection unit (1460) for phase discrimination is connected to each of the plurality of voltage regulation units (1451, 1452). Similarly to the voltage regulation units, in the case of a single phase, two peak detection units for phase discrimination can be configured, and in the case of a three phase, three peak detection units for phase discrimination can be configured. For example, in the case of FIG. 14, the first peak detection unit (1461) can be connected to the first voltage regulation unit (1451), and the second peak detection unit (1462) can be connected to the second voltage regulation unit (1452).

[0226] Each of the peak detection units (1461, 1462) for each phase can be configured to output a signal corresponding to the maximum value of the signal waveform output from each of the voltage control units (1451, 1452). For example, the first peak detection unit (1461) can be configured to output a signal (N1b) corresponding to the maximum value of the output signal (N1a) of the first voltage control unit (1451), and the second peak detection unit (1462) can be configured to output a signal (N2b) corresponding to the maximum value of the output signal (N2a) of the second voltage control unit (1452).

[0227] According to an additional aspect, the peak detection unit (1461, 1462) for the upper judgment may be configured to include a rectifier circuit.

[0228] It includes a plurality of voltage regulation units (1451, 1452) each of which is connected to the secondary power lines (L1, L2) of the insulating unit (1410) at one end and connected to the ground at the other end. The rectifier circuit of the peak detection unit (1461, 1462) for phase discrimination can be configured to include a diode placed between the input and the output and a smoothing capacitor placed between the output and the ground.

[0229] The leakage current detection unit (1430) of the leakage current detection device (1400) may further include a potential comparison unit (1470).

[0230] The potential comparison unit (1470) receives two outputs (N1b, N2b) from among the outputs of the plurality of phase discrimination peak detection units (1461, 1462) and outputs a binary signal (Va, Vb). By using the binary signal, the control unit can process the signal more efficiently. In addition, the sensitivity of the difference value that serves as the standard for phase discrimination can be adjusted by adjusting the resistance of the differential amplifier constituting the potential comparison unit (1470).

[0231] According to an additional aspect, when a resistive leakage current occurs, the control unit (1490) can determine in which power line the leakage current occurred based on the signal of the peak detection unit (1461, 1462) for phase discrimination.

[0232] FIG. 15a is a circuit diagram specifically showing the main configuration of a leakage detection device of an IT system according to one embodiment, in which a leakage phase determination unit is included.

[0233] According to an additional aspect, a leakage detection device (1500) used in an IT system includes a resistive leakage detection unit (1520), a leakage phase determination unit, and a control unit (1490). The resistive leakage detection unit (1520) can be configured in the same manner as the resistive leakage detection unit (120, 220, 1320) of the leakage detection device (100, 200, 1300) described above.

[0234] Referring to FIG. 15, a resistive leakage detection unit (1520) is placed between the secondary neutral point (C) of the insulating unit (1510) and the ground, and transmits a signal (T) related to the presence or absence of resistive leakage from the resistive leakage detection unit (1520) to the control unit (1590).

[0235] The leakage phase determination unit of the leakage detection device (1500) includes a voltage control unit (1550) and a peak detection unit (1460) for phase determination.

[0236] The voltage regulation unit (1550) includes a plurality of voltage regulation units (1551, 1552) each having one end connected to a secondary power line (L1, L2) of the insulation unit (1510) and the other end connected to ground. For example, the voltage regulation unit (1550) may be configured to include two voltage regulation units: a first voltage regulation unit (1551) connected to a first power line (L1) and a second voltage regulation unit (1552) connected to a second power line (L2).

[0237] Each voltage regulator (1551, 1552) can be configured as a voltage distribution circuit using a resistor to output a peak-to-peak voltage signal (N1a, N2a) that is lower than the peak-to-peak voltage of the secondary power lines (L1, L2). At this time, it is preferable to use a high resistance of several tens of MΩ to several hundred MΩ.

[0238] The peak detection unit for upper discrimination includes a plurality of peak detection units (1561, 1562) for upper discrimination, each of which is connected to a plurality of voltage control units (1551, 1552). For example, in the case of FIG. 15, the first peak detection unit (1561) may be connected to the first voltage control unit (1551), and the second peak detection unit (1562) may be connected to the second voltage control unit (1552).

[0239] Each peak detection unit (1561, 1562) for each phase can be configured to output a signal corresponding to the maximum value of the signal waveform output from each voltage control unit (1551, 1552).

[0240] According to an additional aspect, the peak detection units (1561, 1562) for phase discrimination may be configured to include respective rectifier circuits. For example, the first peak detection unit (1561) for phase discrimination may include a first rectifier circuit (1561b), and the second peak detection unit (1562) for phase discrimination may include a first rectifier circuit (1562b). The rectifier circuits (1561b, 1562b) of the peak detection units (1561, 1562) for phase discrimination may include a diode arranged between the input and the output, and a smoothing capacitor arranged between the output and the ground.

[0241] According to an additional aspect, each of the peak detection units (1561, 1562) for phase discrimination includes an operational amplifier circuit (1561a, 1562a) in which the output of the voltage regulation unit (1551, 1552) is input as a positive input and has a feedback loop between the output and the negative input. For example, the peak detection units (1561, 1562) for phase discrimination can be configured to include a non-inverting amplifier or a buffer. Unlike a configuration having a negative input feedback loop such as an inverting amplifier, this configuration can detect while maintaining insulation because the input current does not flow through the feedback loop. This configuration can obtain superior insulation performance compared to a conventional inverting amplifier. It is preferable that the operational amplifier circuits (1561a, 1562a) of the peak detection units (1561, 1562) for phase discrimination use a dual supply.

[0242] According to an additional aspect, when a resistive leakage current occurs, the control unit (1590) can determine in which power line (L1, L2) the leakage current occurred based on the signals (N1b, N2b) of the peak detection units (1561, 1562) for phase discrimination. For example, when a resistive leakage current occurs, the resistive leakage detection unit (1520) transmits a signal (T) related to the occurrence of the resistive leakage current to the control unit (1590). The control unit (1590) checks the signal (T) received from the resistive leakage detection unit (1520) to determine whether a resistive leakage current has occurred. When it is determined that a resistive leakage current has occurred, the voltage of the secondary power lines (L1, L2) of the insulation unit (1510) is input through each voltage control unit (1551, 1552). The input voltages (N1a, N2a) generate output signals (N1b, N2b) through the respective phase-discriminating peak detection units (1561, 1562) and are transmitted to the control unit (1590). The control unit (1590) determines in which power line (L1, L2) a leakage current has occurred based on the signals (N1b, N2b) of the phase-discriminating peak detection units (1561, 1562).

[0243] According to an additional aspect, the leakage detection device (1500) further includes a switch (SW1, SW2) disposed between the secondary power line (L1, L2) of the insulating part (1510) and the voltage regulation part (1551, 1552).

[0244] According to an additional aspect, when a resistive leakage current occurs, the control unit (1590) can operate the phase-discrimination peak detection unit (1561, 1562) by connecting the switches (SW1, SW2), and determine in which power line the leakage current occurred based on the signal of the phase-discrimination peak detection unit (1561, 1562). When the switches (SW1, SW2) are used, the phase-discrimination peak detection unit (1561, 1562) is operated only when a resistive leakage current occurs, thereby enabling efficient operation.

[0245] FIG. 15b is a circuit diagram specifically showing the main configuration of a leakage detection device of an IT system according to a variation of one embodiment, in which a leakage phase determination unit is included.

[0246] Referring to Fig. 15b, the leakage phase determination unit of the leakage detection device (1500) further includes a potential comparison unit (1570). That is, the output signals (N1b, N2b) of the phase determination peak detection units (1561, 1562) are converted into binary signals (Va, Vb) by the potential comparison unit (1570) and input to the control unit (1590).

[0247] The potential comparison unit (1570) receives two outputs from among the outputs of the multiple phase discrimination peak detection units (1561, 1562) and outputs a binary signal. By using the binary signal, the control unit can process the signal more efficiently. In addition, the sensitivity of the difference value that serves as the standard for phase discrimination can be adjusted by adjusting the resistance of the differential amplifier constituting the potential comparison unit (1470).

[0248] According to an additional aspect, the potential comparison unit (1570) may be configured to include a first differential amplifier (1571) and a second differential amplifier (1572) whose inputs are crossed with each other. A binary signal can be output using a pair of differential amplifiers whose inputs are crossed with each other. When the binary signal from the potential comparison unit (1570) is transmitted to the control unit (1590), the control unit (1590) can process the transmitted signal more simply. In order to supply only a positive (+) voltage to the control unit, it is preferable to use a single supply for the operational amplifier used in the potential comparison unit (1570).

[0249] In the case of a single phase, since there are two power lines (L1, L2), the potential comparison unit (1570) receiving two outputs can be configured as one. In this case, the outputs (Va, Vb) of the potential comparison unit (1570) are two.

[0250] In the case of 3-phase, since there are 3 power lines (L1, L2, L3), if the outputs of 2 each are combined (L1-L2, L2-L3, L3-L1), there are 3 combinations, so 3 potential comparison units receiving 2 outputs can be configured. Since each potential comparison unit has 2 outputs, the total number of outputs from the 3 potential comparison units is 6.

[0251] Fault situation L1 voltage L2 voltage TVaVb bit expression Control unit judgment L1 ground fault 0.40V223.9V7.63V10.59V0.62V1, 1, 0L1 resistive leakage L1 1kΩ leakage 0.58V222.9V7.62V10.58V0.67V1, 1, 0L1 resistive leakage L1 10kΩ leakage 2.21V222.1V7.65V10.58V0.67V1, 1, 0L1 resistive leakage L1 30kΩ leakage 6.39V217.5V7.27V10.58V0.67V1, 1, 0L1 resistive leakage L1 100kΩ Leakage 18.75V204.0V6.44V10.58V0.67V1, 1, 0L1 Resistive Leakage L1 200kΩ Leakage 32.75V191.9V5.53V10.51V0.66V1, 1, 0L1 Resistive Leakage L2 Ground 225.0V1.08V7.66V0.67V10.58V1, 0, 1L2 Resistive Leakage L2 1kΩ Leakage 226.1V0.50V7.69V0.67V10.58V1, 0, 1L2 Resistive Leakage L2 10kΩ Leakage 223.6V2.56V7.58V0.67V10.59V1, 0, 1L2 Resistive Leakage L2 30kΩ Leakage 218.9V7.39V7.29V0.67V10.58V1, 0, 1L2 Resistive leakage L2 100kΩ Leakage 204.5V21.53V6.41V0.67V10.60V1, 0, 1L2 Resistive leakage L2 200kΩ Leakage 189.1V37.23V5.51V0.67V10.54V1, 0, 1L2 Resistive leakage L1, L2 5kΩ Leakage 113.5V113.6V2.46V0.64V0.64V1, 0, 0 Resistive phase balance leakage L1, L2 10kΩ Leakage 113.7V113.9V2.46V0.64V0.64V1, 0, 0Resistive phase equilibrium leakage current L1, L2 simultaneous 30kΩ leakage current 114.2V 114.2V 2.44V 0.64V 0.64V 1, 0, 0Resistive phase equilibrium leakage current

[0252] Table 1 presents experimental data for resistive leakage current detection for actual circuits.

[0253] The leakage current detection device was designed according to the single-phase circuit diagram of Fig. 15b. The measurement items are the voltage of the power line (L1 voltage, L2 voltage), the output of the resistive leakage current detection unit (T), and the output signal (Va, Vb) of the potential comparison unit (1570).

[0254] The fault situation was tested by connecting a resistor (0Ω, 1kΩ, 10kΩ, 30kΩ, 100kΩ, 200kΩ) to the L1 power line or a resistor (0Ω, 1kΩ, 10kΩ, 30kΩ, 100kΩ, 200kΩ) to the L2 power line, as shown in Fig. 7.

[0255] The threshold value of the output (T) of the resistive leakage current detection unit was set to 1 when it was above the threshold value based on 2.0 V, and the output of the potential comparison unit was expressed in bits (0, 1) based on 5.0 V.

[0256] When a resistive leakage current occurs in the L1 power line, the output (T) of the resistive leakage detection unit becomes 1, and the outputs (Va, Vb) of the potential comparison unit are 1 and 0, respectively. In other words, when a leakage current occurs in the L1 power line, the bit expression is "1, 1, 0".

[0257] When a resistive leakage current occurs in the L2 power line, the output (T) of the resistive leakage detection unit becomes 1, and the outputs (Va, Vb) of the potential comparison unit are 0 and 1. That is, when a leakage current occurs in the L2 power line, the bit expression is "1, 0, 1".

[0258] When simultaneous leakage currents of the L1 and L2 power lines, i.e., resistive phase equilibrium, occurred, the output (T) of the resistive leakage detection unit became 1, and the outputs (Va, Vb) of the potential comparison unit were 0, 0. That is, when simultaneous leakage currents of the L1 and L2 power lines occurred, the bit expression was "1, 0, 0."

[0259] Therefore, by using the output (T) of the resistive leakage detection unit and the output (Va, Vb) of the potential comparison unit, the L1 resistive leakage, the L2 resistive leakage, and the resistive phase equilibrium leakage can be simply and clearly obtained.

[0260] Fault situation L1 voltage L2 voltage TVaVb Bit expression Control unit judgment L1 10nF 50.10V 198.4V 0.67V 10.58V 0.67V 0, 1, 0 Capacitance not detected L1 20nF 26.96V 219.7V 0.67V 10.59V 0.67V 0, 1, 0 Capacitance not detected L1 30nF 19.12V 223.7V 0.68V 10.59V 0.67V 0, 1, 0 Capacitance not detected L1 40nF 14.22V 225.6V 0.67V 10.59V 0.67V 0, 1, 0 Capacitance not detected L1 50nF11.50V227.0V0.68V10.59V0.67V0, 1, 0Capacitance not detected L2 10nF60.30V180.4V0.66V0.67V9.72V0, 0, 1Capacitance not detected L2 20nF29.50V210.1V0.67V0.67V10.59V0, 0, 1Capacitance not detected L2 30nF21.10V214.2V0.67V0.67V10.58V0, 0, 1Capacitance not detected L2 40nF15.42V215.0V0.67V0.67V10.59V0, 0, 1Capacitance not detected L2 50nF12.12V218.8V0.67V0.67V10.58V0, 0, 1Capacitance not detectedL1, L2 simultaneously 10nF102.8V121.5V0.06V1.85V0.65V0, 0, 0Capacitance not detectedL1, L2 simultaneously 30nF111.2V114.1V0.00V0.65V0.65V0, 0, 0Capacitance not detectedL1, L2 simultaneously 50nF113.0V113.0V0.00V0.65V0.65V0, 0, 0Capacitance not detected

[0261] Table 2 presents experimental data for resistive leakage current detection for actual circuits.

[0262] The leakage current detection device was designed according to the single-phase circuit diagram of Fig. 15b. The measurement items are the voltage of the power line (L1 voltage, L2 voltage), the output of the resistive leakage current detection unit (T), and the output signal (Va, Vb) of the potential comparison unit (1570).

[0263] The fault situation was tested by connecting a capacitor (10nF, 20nF, 30nF, 40nF, 50nF) to the L1 power line or a capacitor (10nF, 20nF, 30nF, 40nF, 50nF) to the L2 power line as shown in Fig. 11.

[0264] The threshold value of the output (T) of the resistive leakage current detection unit was set to 1 when it was above the threshold value based on 2.0 V, and the output of the potential comparison unit was expressed in bits (0, 1) based on 5.0 V.

[0265] Since it is not a resistive leakage current, the output (T) of the resistive leakage current detection unit is 0. Therefore, the control unit can determine that the electrostatic capacitance is not detected.

[0266] Fault situation L1 voltage L2 voltage TVaVb bit expression Control unit judgment L1 Submerged leakage 0.30V225.0V7.71V10.59V0.67V1, 1, 0L1 Resistive leakage L2 Submerged leakage 225.1V0.40V7.69V0.67V10.58V1, 0, 1L2 Resistive leakage L1 L2 Simultaneous submerged leakage 112.7V112.5V2.47V0.64V0.63V1, 0, 0Resistive phase equilibrium leakage

[0267] Table 3 presents experimental data on immersion in actual circuits.

[0268] The leakage current detection device was designed according to the single-phase circuit diagram of Fig. 15b. The measurement items are the voltage of the power line (L1 voltage, L2 voltage), the output of the resistive leakage current detection unit (T), and the output signal (Va, Vb) of the potential comparison unit (1570).

[0269] The fault condition was measured by submerging the power line of the load section in actual water.

[0270] The threshold value of the output (T) of the resistive leakage current detection unit was set to 1 when it was above the threshold value based on 2.0 V, and the output of the potential comparison unit was expressed in bits (0, 1) based on 5.0 V.

[0271] When a submerged leakage current occurs in the L1 power line, the output (T) of the resistive leakage detection unit becomes 1, and the outputs (Va, Vb) of the potential comparison unit are 1 and 0, respectively. That is, when a submerged leakage current occurs in the L1 power line, the bit expression is "1, 1, 0", which represents the same value as the L1 resistive leakage current in Table 1.

[0272] When a submerged leakage current occurs in the L2 power line, the output (T) of the resistive leakage detection unit becomes 1, and the outputs (Va, Vb) of the potential comparison unit are 0 and 1. That is, when a submerged leakage current occurs in the L2 power line, the bit expression is "1, 0, 1", which represents the same value as the L2 resistive leakage current in Table 1.

[0273] When simultaneous submersion leakage occurs in the L1 and L2 power lines, the output (T) of the resistive leakage detection unit becomes 1, and the outputs (Va, Vb) of the potential comparison unit are 0, 0. That is, when simultaneous submersion leakage occurs in the L1 and L2 power lines, the bit expression is "1, 0, 0", which represents the same value as the resistive phase equilibrium leakage in Table 1.

[0274] Therefore, even in the case of immersion leakage, by using the output (T) of the resistive leakage detection unit and the output (Va, Vb) of the potential comparison unit, L1 immersion leakage, L2 immersion leakage, and L1 and L2 simultaneous immersion leakage can be simply and clearly obtained, just like in the case of resistive leakage.

[0275] The detection of phase-balanced resistive leakage current by detecting the waveform characteristics (DC + DC offset or AC + DC offset) in the resistive detection unit and the detection of phase-balanced resistive leakage current from the resistive leakage signal + the signal of the phase discriminator can be implemented in a dual detection structure by cooperating with each other.

[0276] Fig. 16 is a schematic diagram showing the main configuration of a leakage detection device of an IT system according to one embodiment, which includes a leakage phase determination unit, when applied to a three-phase power supply.

[0277] Referring to Fig. 16, the insulating unit (1610) is composed of a three-phase transformer. The secondary side of the insulating unit (1610) is connected to a load (1340) via power lines (L1, L2, L3). The resistive leakage current detection unit (1620) is connected to a neutral line (N) connected to the secondary neutral point of the insulating unit (1610).

[0278] The illustrated leakage current detection device (1600) can be configured to include a resistive leakage current detection unit (1620), a leakage current phase determination unit (1630), and a control unit (1690).

[0279] The resistive leakage detection unit (1620) of the three-phase power supply can be configured in the same manner as the resistive leakage detection unit (1320) of FIG. 13.

[0280] The voltage regulation unit (1650) includes three voltage regulation units, each connected between the power lines (L1, L2, L3) and the ground. Each voltage regulation unit transmits three output signals (N1a, N2a, N3a) to the phase discrimination peak detection unit (1660). The phase discrimination peak detection unit (1660) also includes three phase discrimination peak detection units connected to each voltage regulation unit. Each phase discrimination peak detection unit outputs three output signals (N1b, N2b, N3b) to the potential comparison unit (1670).

[0281] In the case of 3 phases, since there are 3 power lines (L1, L2, L3), if the outputs of 2 each are combined (L1-L2, L2-L3, L3-L1), there are 3 combinations, so the potential comparison unit (1670) includes 3 potential comparison units, each receiving 2 outputs. Since each potential comparison unit has 2 outputs, the total number of outputs (Va, Vb, Vc, Vd, Ve, Vf) of the 3 potential comparison units becomes 6.

[0282] For each component of the leakage current detection device (1600) of a three-phase power supply, the same configuration can be achieved by referring to the description of the corresponding components described above.

[0283] Fig. 17 is a schematic diagram showing the configuration of a capacitive leakage current detection unit in a leakage current detection device of an IT system according to one embodiment.

[0284] According to an additional aspect, the leakage detection device may further include a capacitive leakage detection unit (1780). The capacitive leakage detection unit (1780) includes test resistors (Rt1, Rt2) and voltage detectors (1781, 1782). As described above, the leakage detection device includes an insulating unit (1710) and a resistive leakage detection unit (1720) connected to a neutral point (C) on the secondary side of the insulating unit. An output signal (T) of the resistive leakage detection unit (1720) is input to a control unit (1790). The control unit (1790) can control both the resistive leakage detection unit (1720) and the capacitive leakage detection unit (1780).

[0285] Test resistors (Rt1, Rt2) are connected between power lines (L1, L2) and ground by switches (SWt1, SWt2). The opening and closing of the switches (SWt1, SWt2) is controlled by a control unit (1790). Voltage detectors (1781, 1782) are connected between the test resistors (Rt1, Rt2) and ground.

[0286] The control unit (1790) can detect the voltage caused by the current passing through the test resistors (Rt1, Rt2) by controlling the switches (SWt1, SWt2) at regular time intervals or when receiving an external interrupt signal.

[0287] When the control unit (1790) turns on the first switch (SWt1) while all switches (SWt1, SWt2) are OFF, the first test resistor (Rt1) is connected to the first power line (L1). At this time, a first voltage signal (V1) is output from the first voltage detector (1781) by the current flowing through the first test resistor.

[0288] When a first voltage signal (V1) is received from the first voltage detector (1781), the control unit (1790) turns off the first switch (SWt1) and turns on the second switch (SWt2), thereby connecting the second test resistor (Rt2) to the second power line (L2), and receiving the second voltage signal (V2) from the second voltage detector (1782).

[0289] According to an additional aspect, if the voltage received from the voltage detector (1781, 1782) is higher than the reference voltage, the control unit (1790) changes to a blocking mode that blocks the power line when a resistive leakage current occurs. If the voltage signal (V1, V2) received from the voltage detector (1781, 1782) is higher than the reference value, the control unit (1790) can determine that a capacitive leakage current has occurred. If a capacitive leakage current has occurred, the control unit can be set to operate in a blocking mode rather than an alarm mode when a resistive leakage current signal is received.

[0290] According to an additional aspect, the leakage detection device may further include a resistive leakage alarm device (not shown). The resistive leakage alarm device may include a speaker or a light-emitting diode (LED), etc., and may output an audible or visual alarm signal to the outside when a signal (T) indicating that a resistive leakage has occurred is input from the differential comparison unit of the resistive leakage detection unit (1720). The resistive leakage detection unit (1720) may be connected to a control unit (1790) and may operate by a control signal output when a signal (T) indicating that a resistive leakage has occurred is input to the control unit.

[0291] According to an additional aspect, the leakage detection device (1700) may further include a blocking mode indicator (1797). The blocking mode indicator (1797) may include a speaker or a light-emitting diode (LED), etc., and may externally notify that the leakage detection device is operating in the blocking mode when the operation mode of the leakage detection device is changed to the blocking mode.

[0292] Fig. 18 is a flowchart showing a method for determining an operation mode using a capacitive leakage current detection unit in a leakage current detection device of an IT system according to one embodiment.

[0293] According to another aspect of the proposed invention, a method for detecting a current leakage used in an IT system includes a step in which a control unit (1790) receives a resistive current leakage signal (T) from a resistive current leakage detection unit (1720) (S1810) and determines whether a resistive current leakage exists (S1820). If a resistive current leakage is determined, a resistive current leakage alarm can be output (S1830).

[0294] If there is no resistive leakage current, a leakage current for a power line is generated by connecting test resistors (Rt1, Rt2) between the power lines (L1, L2) and the ground (S1840). Then, a voltage signal is received from a voltage detector (1781, 1782) connected to the test resistors (Rt1, Rt2) to measure the voltage (S1850). The measured voltage is compared with a reference value (S1860), and if the voltage measured for any one of the power lines is greater than the reference value, it means that the capacitance is greater than the reference value, and thus the operation is set to the blocking mode (S1890). When operating in the blocking mode, the operation of the leakage detection device in the blocking mode can be notified externally through the blocking mode display device (1797).

[0295] If there are other power lines that have not been tested (S1870), the test is repeated by generating a leakage current for the untested power lines (S1840). If the measured voltage for all power lines (L1, L2) is lower than the reference value, the alarm mode is set (S1880).

[0296] Fig. 19 is a flowchart showing a method for detecting a leakage state using a leakage detector in a leakage detection device of an IT system according to one embodiment.

[0297] According to another aspect of the proposed invention, a leakage current detection method used in an IT system includes an offset voltage application step (S1910), an amplifier voltage input step (S1920), and an amplified waveform output step (S1930).

[0298] In the offset voltage application step (S1910), a DC offset voltage is applied to the secondary neutral point (C) of the insulation part (110) that separates the primary power distribution line from the secondary IT system power line.

[0299] In the amplifier voltage input step (S1920), the voltage of the low-voltage offset terminal (D) toward the ground of the offset generating unit (150) that applies the DC offset voltage to the secondary neutral point of the insulating unit (110) is input to the amplifier unit (160).

[0300] In the amplification waveform output stage (S1930), the voltage of the low-voltage offset terminal (D) is amplified and output through the first amplifier (161), and a waveform that is inverted from the output of the first amplifier (161) is output through the second amplifier (162). In order to obtain an appropriate output, the gain of each amplifier is set to an appropriate value in advance.

[0301] According to an additional aspect, the amplification waveform output step (S1930) includes a step of transmitting the output voltage of the first amplifier unit (161) to the input of the second amplifier unit (162).

[0302] According to an additional aspect, the leakage current detection method further includes a peak detection step (S1940). In the peak detection step (S1940), the output waveform of the first amplifier unit (161) and the output waveform of the second amplifier unit (162) are input, and a signal corresponding to the maximum value of each is output. The peak detection step (S1940) may include a step of rectifying the input waveform.

[0303] According to an additional aspect, the leakage detection method further includes a differential comparison step (S1950). In the differential comparison step (S1950), a signal corresponding to a maximum value obtained by rectifying the output waveform of the first amplifier unit (161) and a signal corresponding to a maximum value obtained by rectifying the output waveform of the second amplifier unit (162) are input, and a difference between the two input values ​​is compared.

[0304] According to an additional aspect, the leakage current detection method includes a step (S1960) of determining a resistive leakage current if there is a difference between two input values ​​in the differential comparison step. If it is not a resistive leakage current, the measurement can be repeated continuously.

[0305] In case of resistive leakage, a resistive leakage alarm can be output through a resistive leakage alarm device (not shown) (S1965). It is checked whether the set operation mode is alarm mode (S1970), and if it is alarm mode, a resistive leakage alarm, i.e., an alarm signal, is output (S1980). If there is a difference between the two input values ​​in the differential comparison stage and it is in blocking mode, the control unit outputs a signal to block the power line with a circuit breaker (S1990). When the circuit breaker (not shown) receives a power line blocking signal, it blocks the power line to prevent damage to people and the risk of fire due to leakage.

[0306] According to one embodiment, the potential of the other end (D) of the offset generating unit (150) can be maintained at 0 V during normal insulation, thereby minimizing the computational burden of the circuit. When configuring the ADC of the control unit (190), the ADC can be operated based on the output signal (T) of the resistive leakage current detection unit (120) as a judgment criterion, thereby minimizing power consumption. In other words, this invention can be implemented with an efficient structure that consumes power only when necessary.

[0307] Fig. 20 is a flowchart showing a method for identifying a power line in which a leakage current has occurred using a leakage current detector in a leakage current detection device of an IT system according to one embodiment.

[0308] According to an additional aspect, the above leakage detection method further includes a voltage control step (S2020) and a peak detection step for phase discrimination (S2030).

[0309] First, the voltage signal of the secondary power line (L1, L2) of the insulation part (1410) is input (S2010).

[0310] In the voltage regulation step (S2020), the voltage regulation unit (1451, 1452) lowers the peak-to-peak voltage of the voltage signal of the secondary power line (L1, L2) of the insulation unit (1410) and outputs a regulated voltage.

[0311] In the peak detection step for upper discrimination (S2030), the peak detection unit for upper discrimination (1461, 1462) outputs a peak signal for upper discrimination corresponding to the maximum value of the adjusted voltage waveform.

[0312] According to an additional aspect, the leakage detection method further includes a potential comparison step (S2040).

[0313] In the potential comparison step (S2040), the potential comparison unit (1470) receives two signals among multiple peak signals for phase discrimination and outputs a binary signal.

[0314] According to an additional aspect, the potential comparison step (S2040) includes a first differential amplification step and a second differential amplification step.

[0315] In the first differential amplification stage, the first differential amplifier (1571) receives the first signal among the two signals at the positive input, and receives the second signal among the two signals at the negative input.

[0316] In the second differential amplification stage, the second differential amplifier (1572) crosses the signal input to the first differential amplifier (1571), and receives the second signal at the positive input and the first signal at the negative input.

[0317] According to an additional aspect, the above leakage detection method further includes a step (S2050) of identifying a power line in which a leakage has occurred. The control unit (190, 290, 1390, 1490, 1590, 1690, 1790) can identify a power line in which a leakage has occurred using a binary signal output in the potential comparison step (S2040).

[0318] According to an additional aspect, the leakage detection method further includes the steps of connecting a test resistor between a power line and a ground, measuring a voltage from a voltage detector connected to the test resistor, setting the system to an alarm mode when the voltage measured for all power lines is less than a reference value, and setting the system to a blocking mode when the voltage measured for any one power line is greater than the reference value.

[0319] While the present invention has been described above through embodiments illustrated with reference to the attached drawings, it is not limited thereto and should be construed to encompass various modifications that would be readily apparent to those skilled in the art. The scope of the patent claims is intended to encompass such modifications.

[0320] [Explanation of symbols]

[0321] 100, 200, 1300, 1400, 1500, 1600, 1700: Leakage detection device

[0322] 110, 210, 1310, 1410, 1510, 1610, 1710: Insulation

[0323] 120, 220, 1320, 1420, 1520, 1620, 1720: Resistive leakage current detector

[0324] 150, 250, 1350: Offset generator

[0325] 160, 260, 1360: Amplifier

[0326] 170, 270, 1370: Peak detection unit

[0327] 180, 280, 1380: Differential comparison section

[0328] 190, 290, 1390, 1490, 1590, 1690, 1790: Control Unit

[0329] 1451, 1452; 1551, 1552; 1650: Voltage regulator

[0330] 1461, 1462; 1561, 1562; 1660: Peak detection unit for upper discrimination

[0331] 1470, 1570, 1670: Potential comparison section

Claims

1. In a leakage detection device (100, 200, 1300, 1400, 1500, 1600, 1700) used in an IT system in which a secondary power line (L1, L2; L1, L2, L3) to which a load is connected is separated from a primary power distribution line by an insulating member (110, 210, 1310, 1410, 1510, 1610, 1710), An offset generating unit (150, 250, 1350) that is connected to the secondary neutral point (C) of the above-mentioned insulating unit (110, 210, 1310, 1410, 1510, 1610, 1710) and applies a DC offset voltage to the secondary neutral point (C); and It includes an amplifier (160, 260, 1360) which is connected between the offset generating unit (150, 250, 1350) and the ground and receives and amplifies the voltage of the other end (D) of the offset generating unit (150, 250, 1350) toward the ground; The above amplifier (160, 260, 1360) A first amplifier (161, 261, 1361) that receives and amplifies the voltage of the other end (D) of the above offset generating unit (150, 250, 1350); and characterized by including a second amplifier (162, 262, 1362) that outputs a waveform that is inverted from the output of the first amplifier (161, 261, 1361); Leakage detection device (100, 200, 1300, 1400, 1500, 1600, 1700).

2. In paragraph 1, The above second amplifier (162, 262, 1362) It is characterized in that it receives the output of the above first amplifier (161, 261, 1361) as input and outputs an inverted waveform. Leakage detection device (100, 200, 1300, 1400, 1500, 1600, 1700).

3. In paragraph 1 or 2, It is characterized by further including a peak detection unit (170, 270, 1370) that outputs a signal corresponding to the maximum value of the output waveform of the above amplifier unit (160, 260, 1360). Leakage detection device (100, 200, 1300, 1400, 1500, 1600, 1700).

4. In any one of paragraphs 1 to 3, It is characterized by further including a differential comparison unit (180, 280, 1380) that outputs a signal including a DC offset voltage based on the output of the first amplifier unit (161, 261, 1361) and the output of the second amplifier unit (162, 262, 1362). Leakage detection device (100, 200, 1300, 1400, 1500, 1600, 1700).

5. In any one of paragraphs 1 to 4, It is characterized by further including a control unit (190, 290, 1390, 1490, 1590, 1690, 1790) that determines that a resistive leakage current has occurred when there is a difference between the output of the first amplifier unit (161, 261, 1361) and the output of the second amplifier unit (162, 262, 1362). Leakage detection device (100, 200, 1300, 1400, 1500, 1600, 1700).

6. In paragraph 5, The above control unit (190, 290, 1390, 1490, 1590, 1690, 1790) If the output of the above amplifier (160, 260, 1360) is an AC signal including a DC offset, it is determined that a resistive leakage current has occurred rather than a phase balance. When the output of the above amplifier (160, 260, 1360) is a DC signal including a DC offset, it is determined that a phase-balance resistive leakage current has occurred. Leakage detection device (100, 200, 1300, 1400, 1500, 1600, 1700).

7. In paragraph 6, The above control unit (190, 290, 1390, 1490, 1590, 1690, 1790) Characterized in that it is determined whether the resistive leakage is a phase-balance resistive leakage only when it is determined that a resistive leakage has occurred based on the output of the above amplifier (160, 260, 1360). Leakage detection device (100, 200, 1300, 1400, 1500, 1600, 1700).

8. In any one of paragraphs 5 to 7, A plurality of voltage control units (1451, 1452; 1551, 1552; 1650) each having a secondary power line (L1, L2; L1, L2, L3) of the insulating unit (110, 210, 1310, 1410, 1510, 1610, 1710) connected at one end and the other end connected to ground, outputting a peak-to-peak voltage signal smaller than the peak-to-peak voltage of the power line (L1, L2; L1, L2, L3); and It is characterized by further including a plurality of peak detection units (1461, 1462; 1561, 1562; 1660) for phase discrimination, which are connected to each of the plurality of voltage control units (1451, 1452; 1551, 1552; 1650) and output a signal corresponding to the maximum value of the signal waveform output from the voltage control units (1451, 1452; 1551, 1552; 1650). Leakage detection device (100, 200, 1300, 1400, 1500, 1600, 1700).

9. In paragraph 8, The above peak detection unit for the upper judgment (1461, 1462; 1561, 1562; 1660) is characterized in that it includes an operational amplifier in which the output of the voltage regulation unit (1451, 1452; 1551, 1552; 1650) is input as a positive input and a feedback loop is provided between the output and the negative input; Leakage detection device (100, 200, 1300, 1400, 1500, 1600, 1700).

10. In paragraph 8 or 9, It further includes a potential comparison unit (1470, 1670) that receives two outputs among the outputs of the plurality of peak detection units (1461, 1462; 1561, 1562; 1660) for the above-mentioned multiple phase discrimination and outputs a binary signal; The above potential comparison unit (1470, 1670) is A first differential amplifier (1571) that receives the first output, which is one output among the plurality of peak detection units (1461, 1462; 1561, 1562; 1660) for the above-mentioned multiple phase discrimination, as a positive input and receives the second output, which is the other output, as a negative input; and A second differential amplifier (1572) is characterized in that it includes the first output as a negative input and the second output as a positive input, so that the input signal of the first differential amplifier (1571) is input in a crossed manner. Leakage detection device (100, 200, 1300, 1400, 1500, 1600, 1700).

11. In any one of paragraphs 8 to 10, It further includes a switch (SW1, SW2) arranged between the secondary power lines (L1, L2; L1, L2, L3) of the above insulation section (110, 210, 1310, 1410, 1510, 1610, 1710) and the voltage control section (1451, 1452; 1551, 1552; 1650). The above control unit (190, 290, 1390, 1490, 1590, 1690, 1790) When a resistive leakage current occurs, the switch (SW1, SW2) is connected, and based on the signal of the peak detection unit (1461, 1462; 1561, 1562; 1660) for the phase discrimination, it is characterized in that it is determined in which power line the leakage current occurred. Leakage detection device (100, 200, 1300, 1400, 1500, 1600, 1700).

12. In any one of paragraphs 5 to 11, Test resistors (Rt1, Rt2) connected between the secondary power lines (L1, L2; L1, L2, L3) of the above-mentioned insulation section (110, 210, 1310, 1410, 1510, 1610, 1710) and ground by switches (SWt1, SWt2); and characterized in that it further includes a voltage detector (1781, 1782) connected between the test resistor (Rt1, Rt2) and ground; Leakage detection device (100, 200, 1300, 1400, 1500, 1600, 1700).

13. In paragraph 12, The above control unit (190, 290, 1390, 1490, 1590, 1690, 1790) When the voltage received from the voltage detector (1781, 1782) is higher than the reference voltage, the secondary power lines (L1, L2; L1, L2, L3) of the insulating part (110, 210, 1310, 1410, 1510, 1610, 1710) are switched to a blocking mode to block them when a resistive leakage current occurs. Leakage detection device (100, 200, 1300, 1400, 1500, 1600, 1700).

14. In a method for detecting leakage current used in IT systems, An offset voltage application step (S1910) for applying a DC offset voltage to the secondary neutral point (C) of an insulating member (110, 210, 1310, 1410, 1510, 1610, 1710) that separates the primary power distribution line from the secondary power line (L1, L2; L1, L2, L3); A voltage input step (S1920) that inputs the voltage of the terminal (D) toward the ground of the offset generating unit (150, 250, 1350) to the amplifier unit (160, 260, 1360); An amplified waveform output step (S1930) that amplifies the voltage input to the amplification unit (160, 260, 1360) through the first amplification unit (161, 261, 1361) and outputs a waveform that is inverted from the output of the first amplification unit (161, 261, 1361) through the second amplification unit (162, 262, 1362); A peak detection step (S1940) that receives the output waveform of the first amplifier (161, 261, 1361) and the output waveform of the second amplifier (162, 262, 1362) and outputs a signal corresponding to each maximum value; and It is characterized by including a differential comparison step (S1950) that receives a signal corresponding to the maximum value of the output waveform of the first amplifier (161, 261, 1361) and a signal corresponding to the maximum value of the output waveform of the second amplifier (162, 262, 1362) and compares whether there is a difference between the two input values. Method of detecting leakage current.

15. In paragraph 14, A voltage regulation step for lowering the peak-to-peak voltage of the voltage signal of the power lines (L1, L2; L1, L2, L3) to output a regulated voltage; A peak detection step for phase discrimination that outputs a peak signal for phase discrimination corresponding to the maximum value of the regulated voltage waveform; and It further includes a potential comparison step for inputting two signals among multiple peak signals for phase discrimination and outputting a binary signal; The above potential comparison step is, A first differential amplification step for inputting a first signal among the two signals to the positive input of the first differential amplifier (1571) and a second signal among the two signals to the negative input; and A second differential amplification step comprising: a second differential amplifier (1571) that crosses the signal input to the first differential amplifier (1571), inputs the second signal to the positive input of the second differential amplifier (1572), and inputs the first signal to the negative input; Method of detecting leakage current.

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