Leakage Current restriction and Grounding or Electric Leakage Detection System

Abstract

The present invention relates to a ground fault or leakage detection system configured to detect a ground fault or leakage between a power supply side and a load side, comprising: an isolation transformer configured to insulate the power supply between a power distribution line and a power line connected to a load; a leakage current detection unit configured to input the potential of the ground line as a continuous signal when a ground fault or leakage occurs in any one of the lines excluding the ground line, wherein one of the lines of the isolation transformer includes a ground line grounded with high resistance; a detection voltage output unit configured to input the potential of the ground line as a continuous signal and output a set voltage as a detection voltage, wherein the potential output from the leakage current detection unit is input; a comparison detection unit configured to determine a ground fault or leakage by comparing the potential output from the detection voltage output unit with a ground fault judgment setting potential value or a leakage judgment setting potential value configured corresponding to the ground fault or leakage, respectively, and outputting the judgment result; and a digital control unit configured to perform an AND operation or an OR operation on the output from the comparison detection unit. It can distinguish between leakage current and ground fault in the power supplied to the load side, detect and alarm them, and subdivide leakage current categories to not only limit leakage current but also analytically output various leakage current factors.

Description

Technology Field

[0001] The present invention relates to a leakage current limiting and ground fault or leakage current detection system, and more specifically, to a leakage current limiting and ground fault or leakage current detection system with an improved structure that limits the leakage current to a harmless value while distinguishing and detecting ground faults or leakage currents, and can generate an alarm by cutting off or maintaining the power supply to the load side based on the detected result. Background Technology

[0002] There are various indispensable elements necessary to sustain our daily lives and operate industrial facilities. Among these indispensable elements is electricity, which supplies power to various electronic devices and equipment. While this electricity provides convenience, it can also cause accidents.

[0003] These accidents include electrical leakage. Electrical leakage is a phenomenon in which current flows through a path other than the conductor it is originally supposed to flow through.

[0004] Electric shock to the human body in dry conditions, electric shock to the human body in water, and ground faults are collectively referred to as leakage current. Electric shocks that directly affect humans and animals include electric shock to the human body in dry conditions and electric shock to the human body in water. Accidents that do not directly affect humans and animals but can lead to fire include ground faults.

[0005] A ground fault circuit breaker is a device designed to ensure safety from electric shock and fire to humans and animals due to various ground fault phenomena. When a ground fault occurs, the ground fault circuit breaker trips within 0.03 seconds to prevent electric shock or fire.

[0006] However, earth leakage circuit breakers cannot serve as a fundamental safety measure against electric shock and ground fault accidents. In principle, earth leakage circuit breakers detect a leakage and activate the breaker after it occurs, but the instantaneous current just before the breaker trips can affect humans and animals.

[0007] Accordingly, technologies commonly referred to as "shock-free" have been under development for several years. Each company's shock-free technology prevents electric shock accidents caused by leakage current during submersion or while dry, in various forms.

[0008] Therefore, it is desirable to detect leakage currents more effectively by distinguishing between ground faults and leakage currents, and for the user to select whether to cut off or maintain the power supplied to the load side when a ground fault or leakage current occurs.

[0009] In addition, it would be desirable to be able to more effectively determine whether a ground fault or leakage has occurred in any one line.

[0010] [References]

[0011] Registered Patent Publication No. 10-1726340 (Published on April 12, 2017)

[0012] Registered Patent Publication No. 10-2169232 (Published on Oct. 27, 2020) The problem to be solved

[0013] The objective of the present invention is to provide a ground fault or leakage current detection system capable of continuously sensing the potential supplied to the load side, distinguishing between leakage current and ground fault, detecting, and alarming.

[0014] In addition, another objective of the present invention is to provide a ground fault or leakage current detection system that can protect against electric shock even when directly contacting a phase power source in a dry state as well as in the case of submersion through high-resistance grounding, and can improve reliability and safety by utilizing the advantages of analog and digital.

[0015] In addition, another objective of the present invention is to provide a ground fault or leakage current detection system that allows a user to select whether to cut off or maintain the power supplied to the load side in response to the detection of a ground fault or leakage current.

[0016] In addition, another objective of the present invention is to provide a ground fault or leakage current detection system capable of detecting which of a plurality of wires has a ground fault or leakage current regardless of whether it is grounded. means of solving the problem

[0017] The objective of the present invention is achieved by a ground fault or leakage detection system configured to detect a ground fault or leakage between a power supply side and a load side, comprising: an isolation transformer configured to insulate the power between a power distribution line and a power line connected to a load; a leakage current detection unit configured to input the potential of the ground line as a continuous signal when a ground fault or leakage occurs in any one of the lines excluding the ground line, wherein one of the lines of the isolation transformer includes a ground line grounded with high resistance; a detection voltage output unit configured to input the potential of the ground line as a continuous signal and output a set voltage as a detection voltage when the potential output from the leakage current detection unit is input; a comparison detection unit configured to determine a ground fault or leakage by comparing the potential output from the detection voltage output unit with a ground fault judgment setting potential value or a leakage judgment setting potential value configured corresponding to the ground fault or leakage, respectively, and outputting the judgment result; and a digital control unit configured to perform an AND operation or an OR operation on the output from the comparison detection unit.

[0018] In addition, the comparison detection unit comprises a ground fault comparison detection unit that compares a ground fault judgment setting potential value set in response to a ground fault with the potential output from the detection voltage output unit, and outputs 'High' if the potential input from the detection voltage output unit is greater than the ground fault judgment setting potential value, and a leakage current judgment setting potential value set in response to a leakage current, and compares the potential output from the detection voltage output unit with the potential input from the detection voltage output unit, and the potential input from the detection voltage output unit is greater than the leakage current judgment setting potential value see It is desirable to include a leakage current comparison detector that outputs 'High' if the value is larger.

[0019] In addition, it is desirable that the above high resistance range includes 10 kΩ or more.

[0020] In addition, it is preferable that the current range generated through the above high resistance includes 0.01mA to 5mA.

[0021] In addition, it is preferable that the digital control unit outputs a ground fault when the result determined by the comparison detection unit as a ground fault or leakage current is input, and outputs a leakage current when the result determined by the comparison detection unit as a leakage current is input.

[0022] In addition, it is preferable to further include a selection switch unit that selects whether to cut off or maintain the load-side power supply in the event of a ground fault or leakage current based on the output from the digital control unit.

[0023] In addition, it is desirable for the digital control unit to output a ground fault-related output as 'High' when 'High' is input from both the ground fault comparison detection unit and the leakage current comparison detection unit, and to output a leakage current-related output as 'High' when 'High' is input only from the leakage current comparison detection unit.

[0024] Meanwhile, the objective of the present invention is also achieved by a ground fault or leakage detection system configured to detect whether a single line between a power supply side and a load side has a ground fault or leakage, comprising: an insulating part configured to insulate the power between a power distribution line and a power line connected to a load; a leakage current detection part configured to detect the potential of each line branched from the insulating part as a continuous signal and to input a lowered potential of the detected potential; a potential comparison detection part configured to compare and detect the potential of a selected line among the lines input from the leakage current detection part with that of another line; and a digital control part configured to perform an AND operation, an OR operation, or a bit operation on the output of the potential comparison detection part.

[0025] In addition, it is preferable that the above-mentioned potential comparison detection unit is provided with a plurality of unit potential comparison detection units, each comprising a pair of parallel-connected differential amplifiers, wherein the input line of a selected line and the input line of an unselected line can be switched and input.

[0026] In addition, it is preferable that the output terminals output from the differential amplifiers of each unit potential comparison detection unit are connected to the unit comparison detection unit, so that representative values ​​are input to the digital control unit.

[0027] In addition, the representative value output from the pair of output terminals is bitified, and it is desirable to determine which line has a ground fault or leakage current by performing bit operations in the digital control unit.

[0028] Additionally, it is preferable to further include a selection switch unit that selects whether to cut off or maintain the power on the load side in the event of a ground fault or leakage current based on the output output from the digital control unit. According to another aspect of the present invention, a ground fault or leakage current detection system can detect a ground fault or leakage current on the load side that is insulated from the power supply side that supplies power. The ground fault or leakage current detection system includes: an insulation unit that insulates the power line on the power side and the power line on the load side; a leakage current detection unit that detects the potential of each power line on the load side branched from the insulation unit as a continuous signal and outputs a reduced potential of the detected potential; a potential comparison detection unit that compares the potential of one selected line among the lines input from the leakage current detection unit with that of another line and outputs the result of the comparison as a bit; and a digital control unit that performs an AND operation, an OR operation, or a bit operation on the bitified output of the potential comparison detection unit to output a signal identifying the power line that is ground faulted or leakage current. According to an additional aspect, the potential comparison detector comprises a unit potential comparison detector having a first differential amplifier in which a first line selected from the lines input from the leakage current detection unit is input as a first input (positive input) and a second line not selected is input as a second input (negative input), and a second differential amplifier connected in parallel with the first differential amplifier to form a pair, with the input switched so that the first line is input as a second input (negative input) and the second line is input as a first input (positive input). According to an additional aspect, the isolation unit is composed of an isolation transformer. According to an additional aspect, the leakage current detection unit comprises an inverting amplifier circuit having an operational amplifier and a feedback resistor disposed between the output of the operational amplifier and the negative input to output a half-wave signal lower than the input potential; and a rectifier circuit that receives the output of the inverting amplifier circuit and outputs a smoothed DC signal.According to an additional aspect, the operational amplifier of the inverting amplifier circuit receives power from a single power source with one of its power terminals connected to ground, and the rectifier circuit includes a diode into which the output of the inverting amplifier circuit is input and a capacitor connected between the output of the diode and ground. According to an additional aspect, the inverting amplifier circuit is configured to lower the potential input from another power line to 5 volts and output it when a ground fault occurs in one power line. According to an additional aspect, the first differential amplifier and the second differential amplifier each include an operational amplifier that receives power from a single power source with one of its power terminals connected to ground. According to an additional aspect, the unit potential comparison detector further includes a first circuit having a first diode connected to the output of the first differential amplifier and a first capacitor connected between the output of the first diode and ground; and a second circuit having a second diode connected to the output of the second differential amplifier and a second capacitor connected between the output of the first diode and ground. According to an additional aspect, the unit potential comparison detector further comprises: a third diode, one end (anode) of which is connected to the output of the first circuit and the other end (cathode) of which is connected to the output terminal; and a fourth diode, one end (anode) of which is connected to the output of the second circuit and the other end (cathode) of which is connected to the output terminal; and outputs a representative value from an output terminal where the other end of the third diode and the other end of the fourth diode are commonly connected. According to an additional aspect, the digital control unit includes a microcontroller unit (MCU) that determines a ground fault or leakage power line based on the output of the unit potential comparison detector. According to an additional aspect, it further comprises a circuit breaker disposed on the power line between the insulation unit and the load, which cuts off the power line by a trip signal from the digital control unit. According to an additional aspect, it further comprises a selector switch disposed between the digital control unit and the circuit breaker, which can cut off the trip signal from the digital control unit. Effects of the invention

[0029] According to the present invention, a ground fault or leakage current detection system can be provided that continuously detects the potential supplied to the load side, distinguishes between leakage current and ground fault, detects, and alarms.

[0030] In addition, through high-resistance grounding, protection against electric shock can be provided not only in the case of submersion but also when directly contacting the main power supply in a dry state, and a ground fault or leakage current detection system can be provided that enhances reliability and safety by utilizing the advantages of analog and digital.

[0031] In addition, a ground fault or leakage current detection system can be provided that allows the user to select whether to cut off or maintain the power supplied to the load side in response to the detection of a ground fault or leakage current.

[0032] In addition, a ground fault or leakage current detection system can be provided that detects which of the multiple lines has a ground fault or leakage current, regardless of whether it is grounded or not. Brief explanation of the drawing

[0033] FIG. 1 is a circuit diagram of a single-phase two-wire detection system according to an embodiment of the present invention, FIGS. 2a to 2d are circuit diagrams for explaining the operation process of a detection system, FIG. 3 is a circuit diagram of a three-wire detection system according to another embodiment of the present invention, FIG. 4 is a circuit diagram of a four-wire detection system according to another embodiment of the present invention, and FIG. 5 is a circuit diagram according to another embodiment of the present invention, FIGS. 6a to 6 are partial circuit diagrams for explaining the first operation process of FIG. 5, FIGS. 7a and 7b are partial circuit diagrams for explaining the second operation process of FIG. 5. Specific details for implementing the invention

[0034] A leakage current limiting and ground fault or leakage current detection system (1000, hereinafter referred to as the 'detection system') according to one embodiment of the present invention will be described in detail with reference to FIGS. 1 to 7b as follows.

[0035] FIG. 1 is a circuit diagram of a single-phase two-wire detection system according to one embodiment of the present invention, FIG. 2a to 2d are circuit diagrams for explaining the operation process of the detection system, FIG. 3 is a circuit diagram of a three-wire detection system according to another embodiment of the present invention, FIG. 4 is a circuit diagram of a four-wire detection system according to yet another embodiment of the present invention, FIG. 5 is a circuit diagram according to yet another embodiment of the present invention, FIG. 6a to 6e are partial circuit diagrams for explaining the first operation process of FIG. 5, and FIG. 7a to 7b are partial circuit diagrams for explaining the second operation process of FIG. 5.

[0036] Before describing the present invention in more detail, the present invention is capable of various modifications and may take various forms, and therefore embodiments (aspects or examples) are to be described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed forms, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the present invention.

[0037] In each drawing, identical reference numerals, particularly those with identical tens and ones digits, or identical tens, ones, and alphabets, represent components having the same or similar functions; unless otherwise specified, the components referred to by each reference numeral in the drawing should be understood as components conforming to these criteria.

[0038] In addition, in each drawing, the components are depicted with exaggerated sizes or thicknesses, or simplified, for the sake of ease of understanding; however, the scope of protection of the present invention should not be interpreted as being limited by this.

[0039] The terms used in this specification are used merely to describe specific embodiments (aspects or examples) and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, terms such as “comprising” or “consisting of” are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0040] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0041] <1st Example>

[0042] A ground fault or leakage detection system (1000) configured to detect a ground fault or leakage between a power supply side and a load side according to an embodiment of the present invention comprises: an isolation transformer unit (1100) configured to insulate the power between a power distribution line and a power line connected to a load; a leakage current detection unit (1200) configured to input the potential of the ground line as a continuous signal when a ground fault or leakage occurs in any one of the lines excluding the ground line, wherein one line of the isolation transformer unit (1100) includes a ground line grounded with a high resistance (1130); and a detection voltage output unit (1300) configured to output a set voltage as a detection voltage by inputting the potential output from the leakage current detection unit (1200). It is preferable to include a comparison detection unit (1400) that determines a ground fault or leakage by comparing a ground fault judgment setting potential value or a leakage judgment setting potential value set corresponding to a ground fault or leakage, respectively, with a potential output from the detection voltage output unit (1300), and then outputs a judgment result; and a digital control unit (1500) configured to enable AND operation or OR operation on the output from the comparison detection unit (1400).

[0043] In this embodiment, an alarm is sounded by distinguishing between ground faults and leakage currents, and an alarm is sounded without distinguishing whether any single line is ground faulted or has a leakage current. For example, in the case of a three-wire system, an alarm is displayed when a ground fault or leakage current is detected in any one of the first line (refer to 'L1' in the drawing, etc.), the second line (refer to 'L2' in the drawing, etc.), and the third line (refer to 'L3' in the drawing, etc.). This is a part that differs from another embodiment (second embodiment) described later. That is, in the first embodiment, the faulty line is not distinguished, but in the second embodiment, it is possible to detect which line is faulty by distinguishing (whether the fault is in one of L1, L2, and L3, or in multiple lines).

[0044] The detection system (1000) further includes a selection switch unit (1600) that selects whether to cut off or maintain the load-side power supply in the event of a ground fault or leakage current based on the output from the digital control unit (1500); and it is preferable to further include a maintenance alarm relay (1730, Relay2 or R2) that activates an alarm including a lamp while maintaining the load-side power supply selected and operated by the selection switch unit (1600) and connected to a terminal output as 'High' in relation to the ground fault or a terminal output as 'High' in relation to the leakage current, and a cut-off alarm relay (1750, Relay1 or R1) that activates an alarm including a lamp while cutting off the load-side power supply.

[0045] The isolation transformer (1100) isolates the primary side, which is the distribution line, from the secondary side, to which the load is connected. In addition, it serves to limit leakage current to a harmless value by grounding one line, including the neutral point, with high resistance (1130). According to the law of conservation of energy, the current output from the isolation transformer (1100) returns to the isolation transformer (1100). In this process, the current is limited by grounding the return path with high resistance.

[0046] It is preferable that such an isolation transformer unit (1100) includes an isolation transformer or a generator.

[0047] In this embodiment, to limit leakage current, an impedance greater than that of the prior art, called high resistance (1130), is applied. In the prior art, it is common to apply a method of grounding the neutral wire through a resistance of several ohms to several hundred ohms.

[0048] However, in the present invention, by utilizing a high resistance (1130), even if leakage current occurs, it can be limited to a leakage current value that is harmless to humans and animals. That is, the high resistance (1130, reference numbers omitted as necessary below) applied in the present invention preferably includes a range from 10 kΩ to several mega ohms. Through such high resistance, the leakage current value can be limited to 5 mA or less.

[0049] Methods for detecting leakage current in ungrounded or high-resistance grounded systems according to conventional technology include the operation of an SGR (Selecting Ground Relay) utilizing a GPT (Ground Potential Transformer) or the operation of an OCGR relay utilizing a CT. A characteristic of these conventional relay operation methods is that the relay is operated by detecting the amount of ground fault current. For this reason, in order to operate the relay, a ground fault current exceeding a set value must occur. For example, even in the SGR relay operation method utilizing a GPT, the relay operates only when a ground fault current of approximately 380mA occurs during a complete ground fault. Operation using current sensors such as CTs detects ground fault currents of several amperes (A), and such current values ​​exceed the range required to protect against direct electric shock to humans and animals.

[0050] In other words, conventional technologies are limited to limiting the ground fault current to a certain extent and detecting it when a ground fault occurs. For this reason, ground fault detection is difficult in ungrounded delta-connected systems because the ground fault current is so small.

[0051] However, since the present invention is a fault (ground fault or leakage current) potential detection method rather than a current detection method, it is not affected by the amount of current in detection and operation. Therefore, the high resistance value can be adjusted regardless of the amount of current, and accurate measurement and operation are possible even when the power line is insulated from the ground and ungrounded. In addition to these features, it is possible to distinguish and detect whether a specific line is submerged. Furthermore, the present invention provides protection from electric shock not only in the event of submersion but also when directly contacting the line during dry conditions, and enables real-time shutdown and alarm.

[0052] The power supply unit (1800) serves to supply power to circuits such as the leakage current detection unit (1200) and the detection voltage output unit (1300) according to the present invention. The power supply unit (1800) may be an SMPS or may include other known types of DC power supply devices.

[0053] The leakage current detection unit (1200) detects the potential of the neutral point of the isolation transformer (1100) as a continuous signal. For example, when a leakage current occurs, the potential of the neutral point of the isolation transformer (1100) is significantly high, so it is lowered by a certain ratio and applied to the input terminal of a non-inverting amplifier. A voltage value proportional to this is output to the output terminal of the leakage current detection unit (1200).

[0054] The detection voltage output unit (1300) receives a continuous potential as input from the leakage current detection unit (1200), and when a set voltage (e.g., about 0.7V) or higher is applied, the transistor conducts. When the emitter collector terminal of the transistor conducts, a voltage value proportional to the output value of the leakage current detection unit (1200) is output.

[0055] The comparison detection unit (1400) is divided into a ground fault comparison detection unit (1430) and a leakage current comparison detection unit (1450).

[0056] The ground fault comparison detection unit (1430) includes a comparator output utilizing an OP Amp (operational amplifier). The output of the detection voltage output unit (1300) is applied to the non-inverting input terminal of the ground fault comparison detection unit (1430), and a preset value is applied to the inverting input terminal to compare the two values. As a result of the comparison, if the value of the non-inverting input terminal is greater, 'High' is output.

[0057] Here, the value input to the comparison detection unit (1400) is a value that is pre-set in the judgment setting potential value input unit (1370) so that it can serve as a judgment criterion in the comparison detection unit (1400). For example, the value input to the inverting input terminal of the ground fault comparison detection unit (1430) is '4' volt, and the value input to the inverting input terminal of the leakage current comparison detection unit (1450) is '0.5' volt.

[0058] The leakage current comparison detection unit (1450) includes a comparator output utilizing an OP Amp, similar to the ground fault comparison detection unit (1430). The detection voltage of the detection voltage output unit (1300) is applied as a potential to the non-inverting input terminal, and the value previously set in the judgment setting potential value input unit (1370) is applied to the inverting input terminal to compare the two values. If the value of the non-inverting input terminal is greater as a result of the comparison in the leakage current comparison detection unit (1450), 'High' is output.

[0059] The digital control unit (1500) is a digital control unit including a microcontroller unit (MCU). It performs AND and OR operations through the output of the ground fault comparison detection unit (1430) and the output of the leakage current comparison detection unit (1450).

[0060] For example, if 'High' is input to the digital control unit (1500) from both the ground fault comparison detection unit (1430) and the leakage current comparison detection unit (1450), the digital control unit (1500) outputs the ground fault responsible pin as 'High'. On the other hand, if 'High' is input only from the leakage current comparison detection unit (1450), the digital control unit (1500) outputs the leakage current responsible pin as 'High'.

[0061] The selection switch section (1600) is divided into a 'cut-off mode' that cuts off power to the load side and generates an alarm, and a 'maintenance mode' that maintains power to the load side and generates an alarm, in an area that can be pre-set by the user.

[0062] For example, if the user selects 'shortening mode' from the selection switch unit (1600), the circuit is cut off and an alarm is generated at the same time in the event of a ground fault or leakage current. On the other hand, if the user selects 'maintenance mode' from the selection switch unit (1600), power is supplied normally from the circuit and an alarm is generated at the same time in the event of a ground fault or leakage current.

[0063] The relay unit (1700) receives an operation signal from the digital control unit (1500) and drives a relay including, for example, a cutoff alarm relay (1750) and a maintenance alarm relay (1730).

[0064] Depending on the operation of the relay unit (1700), the maintenance lamp (1733), maintenance alarm (1735), cut-off lamp (1733), and cut-off alarm (1735) may light up in response, or emit an alarm, flash, or sound to provide an alarm.

[0065] And, if it is determined that there is a ground fault or a short circuit, it is desirable that the corresponding ground fault lamp (1763) or short circuit lamp (1765) be lit.

[0066] And the power cutoff switch (110) that was not explained is a switch that cuts off the power supplied from the power supply unit (1800).

[0067] Meanwhile, the circuit breaker alarm method and the circuit breaker method according to the present invention differ in the following respects.

[0068] The decision to trip a ground fault circuit breaker is determined by the amount of leakage. Since the circuit breaker detects and trips when a large current flows instantaneously during a ground fault, an electric shock accident may occur due to the large current in the short moment just before it trips.

[0069] On the other hand, since the present invention does not detect or sense the amount of leakage current but rather inputs the potential change of each line as a continuous value and analyzes it at a logic level, unlike a leakage circuit breaker, the resistive current value is limited to 5mA or less even when in direct contact with the leakage point, thereby preventing electric shock accidents. Furthermore, it can provide an alarm or indicate whether to cut off the circuit in this state.

[0070] The operation process of the detection system (1000) having such a configuration is described as follows, divided into the cases of 'ground fault - interruption mode', 'ground fault - holding mode', 'leakage current - interruption mode', and 'leakage current - holding mode' with reference to FIGS. 1 to 2d.

[0071] The present invention is not limited to single-phase two-wire systems but is also applicable to single-phase three-wire systems, three-phase three-wire systems, and three-phase four-wire systems.

[0072] <Example 1> - (Ground Fault - Break-off Mode)

[0073] The following embodiments are methods that, when any line (line) is flooded or grounded, output only whether a fault has occurred without distinguishing between lines, and indicate whether to disconnect or maintain.

[0074] As shown in FIG. 2a, the user first selects 'blocking mode' from the selection switch unit (1600).

[0075] If a ground fault occurs somewhere on the line (see ① in FIG. 2a) (an accident where the L line comes into contact with ground or earth), the line grounded by the high resistance (1130) switches from 0V to 220V (see ③ and ④ in FIG. 2a). Conversely, the line that originally had the phase (phase line) switches from 220V to 0V (see ② in FIG. 2a).

[0076] This is possible because the neutral point of the isolation transformer (1100) is grounded with high resistance. If the neutral point of the isolation transformer (1100) were directly grounded, a massive current and sparks would be generated the moment a ground fault occurs. This is a very dangerous situation. Through this high-resistance grounding, leakage current can be limited to a set range.

[0077] When 220V is applied to the neutral line, a voltage stepped down in proportion to the leakage current detection unit (1200) (inverting amplifier) ​​connected therein is input. The output is formed by the principle of inverting amplification with respect to the input (see ⑤ in Fig. 2a). At this time, the output waveform includes a half-wave. This output half-wave waveform becomes a DC that is smoothed by the diode and capacitor at the subsequent stage.

[0078] When this signal is applied as a gate signal to the detection voltage output unit (1300) (transistor unit), the collector-emitter of the detection voltage output unit (1300) conducts. Simultaneously with conducting, a voltage is output from the detection voltage output unit (1300) (see ⑥ in FIG. 2a, for example, the output voltage is '4.5 Volt'). The output voltage is output in proportion to the magnitude of the value of the leakage current detection unit (1200) (inverting amplifier unit).

[0079] The voltage output from the detection voltage output unit (1300) is applied to the non-inverting input terminals of the ground fault comparison detection unit (1430) and the leakage current comparison detection unit (1450) (comparison unit), respectively.

[0080] Here, the voltages applied to the inversion input terminals of the ground fault comparison detection unit (1430) and the leakage current comparison detection unit (1450), respectively, are as follows.

[0081] A judgment setting potential value input unit (1370), which is a voltage divider circuit through a resistor, is configured, and the lowest reference voltage (e.g., 0.5 Volt) is applied to the inverting input terminal of the leakage current comparison detection unit (1450), and the highest reference voltage (e.g., 4 Volt) is applied to the inverting input terminal of the ground fault comparison detection unit (1430).

[0082] When a ground fault occurs, the ground fault comparison detection unit (1430) (comparison unit) compares the voltages of the two inputs and outputs 'High', and the leakage current comparison detection unit (1450) (comparison unit) likewise compares and outputs 'High' (see ⑦ to ⑩ in FIG. 2a).

[0083] That is, for example, when the detection voltage is 4.5 Volts to the ground fault comparison detection unit (1430) and the maximum value of 4 Volts is input to the judgment setting potential value input unit (1370), the ground fault comparison detection unit (1430) outputs 'High' because the detection voltage of 4.5 Volts is higher than 4 Volts (see ⑦ and ⑧ in FIG. 2a).

[0084] And, when the detection voltage is 4.5 Volts to the leakage current comparison detection unit (1450) and the lowest value of 0.5 Volts is input to the judgment setting potential value input unit (1370), the leakage current comparison detection unit (1450) outputs 'High' because the detection voltage of 4.5 Volts is higher than 0.5 Volts (see ⑨ and ⑩ in FIG. 2a).

[0085] The 'High' output from the two detection circuits of the ground fault comparison detection unit (1430) and the leakage current comparison detection unit (1450) is applied as an input to the digital control unit (1500) including the microcontroller unit at the rear end (see ⑧ and ⑩ in FIG. 2a).

[0086] When 'High' is input to both input pins, the digital control unit (1500) performs an AND operation and outputs 'High' to the relay unit (1700) and the ground fault responsible pin (see ⑪, ⑫, ⑬, and ⑮ in FIG. 2a). Since the relay unit (1700) is selected to cut off mode by the selector switch unit (1600), it turns on the cut-off alarm relay (1750, hereinafter referred to as 'R1') and simultaneously cuts off the main circuit (AC power circuit) and generates an alarm (see ⑭ in FIG. 2a). Then, as 'High' is output to the ground fault responsible pin, the ground fault lamp (1763), which includes a ground fault warning LED, begins to blink (blink blink) (see original symbol '16' in FIG. 2a).

[0087] When the user resolves the malfunction and presses the reset button, the circuit returns to its original state and operates normally.

[0088] <Example 2> (Ground Fault - Hold Mode)

[0089] As shown in FIG. 2b, the user first selects 'hold mode' from the selection switch unit (1600).

[0090] In the following second embodiment, the description of parts identical to those in the first embodiment is omitted. That is, as shown in FIG. 2b, the part set to 'maintenance mode' and the maintenance alarm relay (1730, hereinafter referred to as 'R2') part are different from FIG. 2a.

[0091] Since 'maintenance mode' is selected in the selection switch section (1600), N2 is turned ON, and the circuit (AC power circuit) maintains normal power and simultaneously generates an alarm (see ⑭ in FIG. 2b). Additionally, as High is output to the ground fault pin, the ground fault lamp (1763) begins to blink (blinking, see original symbol '16' in FIG. 2b). When the user resolves the fault and presses the reset button, the circuit (including the alarm) returns to its original state and operates normally.

[0092] <Example 3> (Leakage - Break-off Mode)

[0093] As shown in FIG. 2c, the user first selects 'blocking mode' from the selection switch unit (1600).

[0094] If a short circuit occurs somewhere along the next line (see ① in Fig. 2c), the accident in which the phase line comes into contact with the earth or ground through a specific resistor may include electric shock to the human body due to direct contact with the conductor, electric shock to the human body due to a submerged conductor, or short circuit in the form of current flowing to the earth through the resistor.

[0095] A constant voltage is applied to the neutral line connected to the isolation transformer (1100) (see ③ and ④ in FIG. 2c). The 220V voltage applied to the existing phase line is also reduced proportionally by the amount of the applied voltage (see ② in FIG. 2c). This is determined by the voltage distribution between the high resistance grounded at the neutral point and the resistance value of the leakage point.

[0096] The input of the leakage current detection unit (1200) (inverting amplifier) ​​is connected to the neutral line. A constant voltage is applied as input by stepping it down through the circuit configuration of the leakage current detection unit (1200). The leakage current detection unit (1200) receives a continuous value as input and outputs a continuous value proportionally (see ⑤ in FIG. 2c).

[0097] The output of the leakage current detection unit (1200) becomes a smoothed DC current through a diode and a capacitor.

[0098] This DC voltage is applied to the detection voltage output unit (1300) (transistor unit), and the detection voltage output unit (1300) (transistor unit) outputs a value proportional to the output of the leakage current detection unit (1200) (see ⑥ in FIG. 2c). Typically, when a leakage current occurs, the value output from the leakage current detection unit (1200) has a value of 1 Volt or more and less than 4 Volts.

[0099] The voltage output from the detection voltage output unit (1300) is applied to the non-inverting input terminals of the ground fault comparison detection unit (1430) and the leakage current comparison detection unit (1450) (comparison unit), respectively.

[0100] Here, the voltages applied to the inversion input terminals of the ground fault comparison detection unit (1430) and the leakage current comparison detection unit (1450), respectively, are as follows.

[0101] A judgment setting potential value input unit (1370), which is a voltage divider circuit through a resistor, is configured, and the lowest reference voltage (e.g., 0.5 Volt) is applied to the inverting input terminal of the leakage current comparison detection unit (1450), and the highest reference voltage (e.g., 4 Volt) is applied to the inverting input terminal of the ground fault comparison detection unit (1430).

[0102] In the ground fault comparison detection unit (1430), since the inverting input terminal voltage (e.g., less than 4 Volt) is greater than the non-inverting input terminal voltage (e.g., less than 4 Volt), the ground fault comparison detection unit (1430) outputs 'Low', unlike in the case of a ground fault (see ⑦ and ⑧ in FIG. 2c).

[0103] On the other hand, since the non-inverting input terminal voltage of the leakage current comparison detection unit (1450) (e.g., 1 Volt or more and less than 4 Volts) is greater than the inverting input terminal voltage (e.g., 0.5 Volts), the leakage current comparison detection unit (1450) outputs 'High' (see ⑨ and ⑩ in FIG. 2c).

[0104] The output voltages of the ground fault comparison detection unit (1430) and the leakage current comparison detection unit (1450) are applied to the digital control unit (1500) (see ⑧ and ⑩ in FIG. 2c). When 'Low' and 'High' are applied to the digital control unit (1500) respectively, the digital control unit (1500) outputs 'High' to the relay unit (1700) and the leakage current responsible pin through an OR operation (see ⑪, ⑫, ⑬ and ⑮ in FIG. 2c).

[0105] The relay unit (1700) turns R1 'ON' because the selector switch unit (1600) has selected the cutoff mode.

[0106] Upon operation of 'R1', the main circuit (AC power circuit) is cut off and an alarm sounds (see ⑭ in Fig. 2c). Additionally, the LED blinks through the leakage current pin (see original symbol '16' in Fig. 2c).

[0107] When the user resolves the malfunction and presses the reset button, the circuit returns to its original state and operates normally.

[0108] <Example 4> (Leakage - Maintenance Mode)

[0109] As shown in FIG. 2d, the user first selects 'hold mode' from the selection switch section (1600).

[0110] In the following fourth embodiment, the description of the parts identical to those in the third embodiment is omitted. That is, the part set to 'maintenance mode' as in FIG. 2d and the maintenance alarm relay (1730, hereinafter referred to as 'R2') part are different from FIG. 2c.

[0111] Since the 'maintenance mode' is selected in the selection switch section (1600), R2 is turned ON, and the circuit (AC power circuit) maintains normal power and simultaneously generates an alarm (see ⑭ in FIG. 2d). In addition, High is output to the leakage current pin, and the leakage current lamp (1765) begins to blink (blinking, see original symbol '16' in FIG. 2d). When the user resolves the malfunction and presses the reset button, the circuit (including the alarm, etc.) returns to its original state and operates normally.

[0112] <2nd Example>

[0113] A detection system (2000) according to another embodiment of the present invention preferably comprises: an insulation unit (2100) configured to be able to insulate power between a power distribution line and a power line connected to a load, and capable of detecting whether a line between a power supply side and a load side has a ground fault or leakage current as illustrated in FIGS. 5 to 7b; a leakage current detection unit (2200) configured to detect the potential of each line branched from the insulation unit (2100) as a continuous signal and to input a lowered potential of the detected potential; a potential comparison detection unit (2300) configured to compare and detect the potential of a selected line among the lines input from the leakage current detection unit (2200) with that of another line; and a digital control unit (2500) configured to enable AND operation, OR operation, or bit operation on the output of the potential comparison detection unit (2300).

[0114] In this embodiment, unlike the above, it is possible to detect which line (road) has a ground fault or is flooded (leakage), and while detecting and notifying the faulty line, it is possible to select whether to maintain or disconnect the faulty line.

[0115] In this embodiment, unlike the embodiment described above, the high resistance is shown as not being grounded, but this does not exclude the high resistance grounded as described above.

[0116] The power supply unit (2800) serves to supply power to circuits such as the leakage current detection unit (2200), potential comparison detection unit (2300), digital control unit (2500), selection switch unit (2600), and relay unit (2700) according to the present invention. The power supply unit (2800) may be an SMPS or may include other known types of DC power supply devices.

[0117] The leakage current detection unit (2200) detects the potential of one of the lines (see L1, L2, L3 in FIG. 5) of the insulation unit (2100) as a continuous signal. For example, when a leakage current occurs, the potential of the neutral point of the insulation unit (2100) or the potential of each line is considerably high, so it is lowered by a certain ratio and applied to the input terminal of the non-inverting amplifier of the leakage current detection unit (2200). A voltage value proportional to this is output to the output terminal of the leakage current detection unit (2200).

[0118] Unlike the embodiment described above, this embodiment does not include a detection voltage output unit and a comparison detection unit.

[0119] The value output from the leakage current detection unit (2200) is input to the subsequent potential comparison detection unit (2300).

[0120] It is preferable that the potential comparison detection unit (2300) is provided with a plurality of unit potential comparison detection units (2310 to 2330), each comprising a pair of parallel-connected differential amplifiers that allow the input line of one selected line and the input line of one unselected line to be switched and input.

[0121] In addition, it is preferable that a pair of output terminals output from the differential amplifiers of each unit potential comparison detection unit (2310 to 2330) are connected to the digital control unit (2500) and input to each of them. In addition, it is preferable that the values ​​output from the pair of output terminals are bitified, and that the digital control unit (2500) performs bit operations on the input bit values ​​to determine which line has a ground fault or leakage current.

[0122] The configuration and specific operation process of such potential comparison detection unit (2300) will be described later with reference to FIGS. 6a to 6d.

[0123] In the selection switch unit (2600), the user can select whether to cut off or maintain the load-side power supply in the event of a ground fault or leakage current based on the output from the digital control unit (2500).

[0124] The relay unit (2700) is equipped with a plurality of relays that receive a signal output from the digital control unit (2500) and generate information or an alarm regarding whether a ground fault or leakage has occurred in a line, whether to cut off, or to maintain.

[0125] Here, 'Re1' in FIG. 5 represents a maintenance alarm relay for line 'L1', 'Re2' represents a maintenance alarm relay for line 'L2', 'Re3' represents a maintenance alarm relay for line 'L3', 'Re4' represents a maintenance alarm relay for multiple lines among lines 'L1', 'L2', and 'L3', and 'Re5' represents a circuit breaker alarm relay when a problem occurs in one or more of the three lines.

[0126] The power supply unit (2800) is the same as the embodiment described above, so the description is omitted.

[0127] The operation process of the detection system (2000) according to the present embodiment having such a configuration is explained as follows with reference to FIGS. 5 to 7b.

[0128] This embodiment uses a three-phase three-wire delta connection as an example, but other connection methods are not illustrated simply because their principles are identical. Additionally, for ease of understanding, a ground fault situation is used as an example, but it is not limited to ground fault situations.

[0129] <Example 1> [Ground Fault + Break-off Mode]

[0130] This is an example where the user selects 'block' for the selection switch unit (2600) to detect whether a ground fault has occurred on one of the lines and to block the line if a ground fault occurs.

[0131] As illustrated in Fig. 6a, when a ground fault occurs somewhere (see ① in Fig. 6a), the potential of the line where the ground fault occurred (see 'L1' in Fig. 6a) becomes '0' (see ② in Fig. 6a), and in an ungrounded system, when one line is grounded, the remaining healthy phases (see 'L2' and 'L3' in Fig. 6a) experience a potential rise of up to √3 times the normal phase voltage due to the potential rise phenomenon caused by the ground fault or leakage (see ③ in Fig. 6a).

[0132] For example, when a ground fault occurs in phase L1, phase L1 becomes '0' potential, and the potentials of phases L2 and L3 increase by up to √3 times the normal state potential. At this time, the leakage current detection unit (2200) of each line (row) receives the potential of each phase from the insulation unit (2100) as a continuous signal. Since the potential of each phase is a considerably high potential, it is characterized by applying a reduced potential when applied to the leakage current detection unit (2200).

[0133] As illustrated in FIG. 6b, a specific potential of each phase is output in the form of a half-wave by the inverting amplifier circuit of the leakage current detection unit (2200), and the half-wave passes through a rectifier circuit through a diode and a capacitor to be output as a smoothed DC. The output potential value of each phase output from the leakage current detection unit (2200) is applied to the potential comparison detection unit. For example, the potential of L1 passing through the leakage current detection unit (2200) is '0' volt (see ④ and 'P1' in FIG. 6b), and the potentials of L2 and L3 are lowered to about 5 volts in the leakage current detection unit (2200) (see ⑤ and ⑥ and 'P2' and 'P3' in FIG. 6b).

[0134] As illustrated in FIG. 6c, the process of first comparing the respective potential values ​​'P1' and 'P2' of the 'L1' and 'L2' lines in the potential comparison detection unit (2300) is explained as an example.

[0135] The potential comparison detection unit (2300) is characterized by including a unit potential comparison detection unit (2310 to 2330) that double-detects the potentials of two phases to be compared (e.g., 'P1' and 'P2', 'P2' and 'P3', and 'P3' and 'P1') through a differential amplifier circuit. The unit potential comparison detection unit (2310 to 2330) is characterized by two differential amplifiers double-monitoring, and the output value is output as a single representative value through two diodes. Here, the unit potential comparison detection unit (2310 to 2330) having a pair of differential amplifiers connected in parallel compares the inputs of two lines that are mutually switched and output, converts the result into bits, and outputs it.

[0136] An embodiment of the potential comparison detection unit (2300) is described in detail as follows. Potentials 'P1' and 'P2' are applied from the respective leakage current detection units (2200) of L1 and L2 (see '⑦ 0 volt' of 'P1' and '⑧ 5 volt' of 'P2' in FIG. 6c). The two potentials are each connected to the differential amplifier input of the unit potential comparison detection unit (2310) at the very front end of FIG. 6c, and the potentials at both ends are compared. When a potential difference occurs as a result of the comparison, it is output in the form of a positive or negative value. In the present invention, negative output is not used, so when output in the form of a negative value, it becomes '0' V. Here, if '0' V is output, a logic error occurs in this circuit, so the input terminals of the differential amplifier are switched to form another differential amplifier. The previous differential amplifier outputs '0'V (see '⑩ 0V' in Fig. 6c), but another differential amplifier outputs a positive voltage (see '⑪ 5V' in Fig. 6c) (see 'High Level', 'D1', and 'D3' in Fig. 6c).

[0137] The result of the unit potential comparison detection unit (2310 to 2330) is finally output in a form that is commonly connected with two diodes to maintain the current direction in a unidirectional manner for the output terminals of the two differential amplifiers.

[0138] As a result of the comparison, if no potential difference occurs between the two ends, the potential comparison detection unit (2300) configured with a dual detection structure outputs '0'V (see 'Low Level' and 'D2' in FIG. 6c).

[0139] The above process compares the potential values ​​'P2' and 'P3' of 'L2' and 'L3' (refer to the second unit potential comparison detection unit (2320) in FIG. 6c), compares the potential values ​​'P3' and 'P1' of 'L3' and 'L1' (refer to the third unit potential comparison detection unit (2330) in FIG. 6c), and outputs a representative value (refer to 'D1', 'D2', and 'D3' in FIG. 6c). The output value is converted into bits and applied to the digital control unit (2500).

[0140] As illustrated in FIG. 6d, the digital control unit (2500) converts the signal received from the potential comparison detection unit (2300) into bits and performs bit operations. For example, when values ​​of 1 / 0 / 1 (refer to 'D1' - High, 'D2' - Low, and 'D3' - High in FIG. 6d) are received from three comparison potential detection units, the corresponding output pin is output as high (refer to 'circle symbol 16' - 'L1 corresponding pin High output' in FIG. 6d).

[0141] Accordingly, the output high turns on the output relay corresponding to the line where the ground fault occurred. At the same time, audiovisual information indicating that a ground fault has occurred on line 'L1' can be simultaneously provided through an LCD panel connected to the digital control unit (2500). Since the output is in the cutoff alarm mode, the cutoff alarm relay turns on (refer to 'circle symbol 17' 'cutoff alarm relay on' in FIG. 6d) and the circuit is cut off (refer to 'circle symbol 18' 'trip coil on' in FIG. 6d / refer to 'circle symbol 20' 'circle breaker trip' in FIG. 6e).

[0142] As shown in FIG. 6e, the corresponding alarm sounds (see 'circle symbol 19' 'blocking alarm buzzer on' in FIG. 6e).

[0143] <Example 2>

[0144] The parts of this embodiment that are not specifically described are the same as <Example 1> described above.

[0145] As illustrated in FIG. 7a, the digital control unit (2500) converts the signal received from the potential comparison detection unit (2300) into bits and performs bit operations. For example, when values ​​of 1 / 0 / 1 (refer to 'D1' - High, 'D2' - Low, and 'D3' - High in FIG. 7a) are received from three comparison potential detection units, the corresponding output pin is output as high (refer to 'circle symbol 16' - 'L1 corresponding pin High output' in FIG. 7a).

[0146] Accordingly, the output high turns on the output relay corresponding to the line where the ground fault occurred (refer to 'symbol 17' '(L1) Maintenance Alarm Relay' in FIG. 7a). At the same time, audiovisual information indicating that a ground fault has occurred on line 'L1' can be simultaneously provided through an LCD panel connected to the digital control unit (2500). Since the output is in maintenance alarm mode, 'Re1' among the maintenance alarm relays turns on (refer to 'symbol 17' in FIG. 7a), and the circuit is not cut off.

[0147] As shown in FIG. 7b, the corresponding alarm sounds (see 'circle symbol 18' '(L1) maintenance alarm buzzer on' in FIG. 7b).

[0148] The above describes the case where a ground fault occurs in only one line.

[0149] It goes without saying that this embodiment can detect not only ground faults but also cases where at least one line is leaking.

[0150] That is, although the present embodiment (the second embodiment) has only described the case of a ground fault, a person skilled in the art to which this technology pertains can easily understand that in the case of a leakage current, by referring to the previously explained content (the first embodiment) and the description of the present embodiment, detecting whether to maintain or disconnect the line when a leakage current occurs in at least one line in the second embodiment, and providing an alarm, so a detailed explanation is omitted.

[0151] As can be seen from the preceding description, the present invention operates analogically when receiving a continuous signal of potential. In other words, analog is advantageous because it allows for the extensive processing of individual outputs for continuous values.

[0152] On the other hand, digital outputs that have only two signals, 'High' and 'Low', are advantageous. Even in this case, if the output is processed analogously, the processing of ambiguous signals may be insufficient. Accordingly, the present invention can produce a constant and accurate output by utilizing a digital control unit (1500) including a microcontroller unit.

[0153] This combination of analog and digital is desirable as it allows us to utilize both the advantages of analog, such as the ability to process a wide range of input signals, and digital, such as the ability to produce constant and accurate output.

[0154] In addition, the present invention can limit leakage current even when one line is submerged as well as two lines, and can limit leakage current even in the event of a ground fault.

[0155] Furthermore, the present invention has the advantages of enabling audiovisual alarms (generating lamps and alarms) when a line is flooded, limiting leakage current even when a single conductor is directly contacted, distinguishing between ground faults and ground faults, allowing the user to select whether to continue power supply to the load side (cutoff mode or hold mode) in the event of a ground fault or ground fault, and enabling operation without matching polarity.

[0156] Accordingly, according to the present invention, a ground fault or leakage current detection system can be provided that continuously detects the potential supplied to the load side, distinguishes between leakage current and ground fault, detects, and alarms.

[0157] In addition, through high-resistance grounding, protection against electric shock can be provided not only in the case of submersion but also when directly contacting the main power supply in a dry state, and a ground fault or leakage current detection system can be provided that enhances reliability and safety by utilizing the advantages of analog and digital.

[0158] In addition, a ground fault or leakage current detection system can be provided that allows the user to select whether to cut off or maintain the power supplied to the load side in response to the detection of a ground fault or leakage current.

[0159] In addition, a ground fault or leakage current detection system can be provided that detects which of the multiple lines has a ground fault or leakage current, regardless of whether it is grounded or not.

[0160] Although an embodiment of the present invention has been illustrated and described herein, those skilled in the art will understand that modifications to this embodiment can be made without departing from the principles or spirit of the invention. The scope of the invention will be defined by the appended claims and their equivalents. Explanation of the symbols

[0161] 1000: Detection system 1100: Isolation transformer 1110: Ground wire 1130: High resistance 1200 : Leakage current detection unit 1300: Detected voltage output unit 1370: Judgment setting potential value input unit 1400 : Comparison detection unit 1430 : Ground fault comparison detection unit 1450 : Leakage current comparison detection unit 1500: Digital control unit 1600: Selector switch unit 1700: Relay section 1730: Maintenance alarm relay 1733 : Maintenance lamp 1735 : Maintenance alarm 1750 : Cut-off alarm relay 1733 : Cut-off lamp 1735 : Circuit Breaker Alarm 1763 : Ground Fault Lamp 1765 : Leakage lamp 1800 : Power supply unit 110 : Power cutoff switch 2000: Detection system 2100: Insulation part 2200 : Leakage current detection unit 2300 : Potential comparison detection unit 2310, 2320, 2330 : Unit potential comparison detector 2500: Digital control unit 2600: Selector switch unit 2700: Relay section 2800: Power supply section

Claims

Claim 1 A ground fault or leakage current detection system for detecting a ground fault or leakage current between a power supply side and a load side that is insulated from the power supply side, comprising: an insulating part that insulates the power line of the power supply side and the power line of the load side; a leakage current detection part that detects the potential of each power line of the load side branched from the insulating part as a continuous signal and outputs a reduced detected potential; and a potential comparison detection part that compares the potential of one selected line among the lines input from the leakage current detection part with that of another line, and outputs the result of the comparison as a bit. A ground fault or leakage detection system comprising: a digital control unit that performs an AND operation, an OR operation, or a bit operation on the bitified output of the potential comparison detection unit to output a signal identifying a power line that is ground faulted or has a leakage current; wherein the potential comparison detection unit comprises a unit potential comparison detection unit having a first differential amplifier in which a first line selected from the lines input from the leakage current detection unit is input as a first input and a second line not selected is input as a second input, and a second differential amplifier connected in parallel with the first differential amplifier to form a pair, with the inputs switched so that the first line is input as a second input and the second line is input as a first input. Claim 2 A ground fault or leakage current detection system according to claim 1, wherein the insulation part is composed of an insulation transformer. Claim 3 A ground fault or leakage current detection system according to claim 1, wherein the leakage current detection unit comprises: an inverting amplifier circuit having an operational amplifier and a feedback resistor disposed between the output of the operational amplifier and a negative input to output a half-wave signal lower than the input potential; and a rectifier circuit receiving the output of the inverting amplifier circuit and outputting a smoothed DC signal. Claim 4 A ground fault or leakage current detection system according to paragraph 3, wherein the operational amplifier of the inverting amplifier circuit has one of its power terminals connected to ground to receive power from a single power source, and the rectifier circuit includes a diode into which the output of the inverting amplifier circuit is input and a capacitor connected between the output of the diode and ground. Claim 5 In paragraph 3, the inverting amplifier circuit is configured to lower the potential input from another power line to 5 volts and output it when a ground fault occurs in one power line, in a ground fault or leakage current detection system. Claim 6 A ground fault or leakage current detection system according to claim 1, wherein the first differential amplifier and the second differential amplifier each include an operational amplifier in which one of the power terminals is connected to ground and receives power from a single power source. Claim 7 A ground fault or leakage current detection system according to claim 6, wherein the unit potential comparison detection unit further comprises: a first circuit having a first diode connected to the output of the first differential amplifier and a first capacitor connected between the output of the first diode and ground; and a second circuit having a second diode connected to the output of the second differential amplifier and a second capacitor connected between the output of the first diode and ground. Claim 8 In claim 7, the unit potential comparison detection unit further comprises: a third diode, one end of which is connected to the output of the first circuit and the other end of which is connected to an output terminal; and a fourth diode, one end of which is connected to the output of the second circuit and the other end of which is connected to an output terminal; thereby outputting a representative value from an output terminal to which the other end of the third diode and the other end of the fourth diode are commonly connected, in a ground fault or leakage current detection system. Claim 9 A ground fault or leakage detection system according to claim 1, wherein the digital control unit comprises a microcontroller unit (MCU) that determines a ground fault or leakage power line based on the output of the unit potential comparison detection unit. Claim 10 A ground fault or leakage current detection system according to claim 1, further comprising a circuit breaker disposed on the power line between the insulation part and the load, and interrupting the power line by a trip signal of the digital control part. Claim 11 A ground fault or leakage current detection system according to claim 10, further comprising a selection switch unit disposed between the digital control unit and the circuit breaker, capable of blocking the trip signal of the digital control unit. Claim 12 delete

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