Safety apparatus for cutting off leakage current

Abstract

The present invention discloses a safety device for interrupting leakage current, comprising: an isolation transformer connected to an electrical power source on the input side; a measuring means for measuring the state of the isolation transformer; a control means for generating a current limit value by comparing a measured value generated using the measuring means with a reference value; a current limiting means having a function for limiting the current according to the capacity of the load and supplying a microcurrent of permissible electric shock value to the load using the current limit value; and a grounding means for providing grounding with the measuring means.

Description

Technology Field

[0001] The present invention relates to a safety device for blocking leakage current, and more specifically, to a technology that limits the current to a level of electric shock that is not harmful to the human body and allows the limited microcurrent to flow to the load to prevent electric shock, power outage, and fire accidents. Background Technology

[0002] FIG. 1 illustrates an example of supplying electricity directly from an electric power source to a load. In the past, electricity could be supplied from an electric power source, such as a power distribution facility or an energy storage facility, and directly connected to the load. In order to prevent damage caused by overload or short circuit, as described in the patent document described as prior art, a circuit breaker was installed to automatically cut off the circuit of the electric power source.

[0003] Loads using electrical signals can exist in homes, companies, or various industrial sites, and in industrial sites, there may be areas of current flow, such as water or metal, that can be a cause of electric shock or current flow.

[0004] Electric shock is the occurrence of injury or a sensation caused by the body coming into contact with an electrically conductive object and allowing current to flow; it can frequently occur in industrial settings. Electric shock is a phenomenon in which the human body reacts when the current flowing from a power source through the body to the ground (the surface of the earth) exceeds a certain level. Generally, a current of 15mA or more causes convulsions, and a current of 50mA or more can result in death. The primary cause of death is cardiac arrest, in which the heart stops due to the current flowing through the heart damaging the nerves.

[0005] For example, when an electrical outlet, heater, or light fixture is submerged in water and the human body comes into contact with it, current flows from the exposed conductor of the electrical equipment through the water and the human body to the ground, which is the grounding surface. In this case, the human body's skin is likely to be wet from the rain, and the contact resistance becomes extremely low, which can be dangerous.

[0006] Therefore, conventionally, there is a need for technology capable of controlling the load to prevent electric shock accidents even in the current-carrying area. Prior art literature

[0007] Korean Registered Patent No. 10-1930804 The problem to be solved

[0008] To solve the above problem, the present invention provides a safety device for blocking leakage current that supplies a microcurrent of an allowable electric shock limit to a load by utilizing an isolation transformer, a current limiting means, and a grounding means together. means of solving the problem

[0009] A safety device for blocking leakage current according to an embodiment of the present invention for the above-mentioned problem to be solved comprises an isolation transformer (100) connected to an electrical power source on the input side, a measuring means (200) for measuring the state of the isolation transformer, a control means (800) for generating a current limit value by comparing a measured value generated using the measuring means with a reference value, a current limiting means (900) equipped with a function to limit the current according to the capacity of the load and supplying a microcurrent of an allowable electric shock limit to the load using the current limit value, and a grounding means (300) for providing grounding with the measuring means, and is characterized by preventing electric shock accidents and power outages by using the isolation transformer, the current limiting means, and the grounding means together.

[0010] The above measuring means may include a frequency modulation compensation unit (210) that compensates for the output side frequency of the isolation transformer and a zero-sequence current transformer (220) that measures the output side current of the isolation transformer, and the control means may include a leakage current analyzer (810) that receives the signal value of the frequency modulation compensation unit and operates in conjunction with it, generates a correction value by comparing the measurement value using the zero-sequence current transformer with a set reference value, and generates an alarm when a measurement value exceeding the set reference value is received, and a microcontroller (820) that stores reference values ​​for IGR values ​​and IGC values ​​according to the capacity of the load and generates a variable current limit value in real time using the correction value generated by the leakage current analyzer.

[0011] The above measuring means includes a power factor controller (230) formed at the downstream end of the frequency modulation compensation unit and the image current transformer to control the power factor, a temperature sensor (240) to measure the temperature of the isolation transformer, and a temperature controller (250) to control the temperature of the isolation transformer based on the measured value of the temperature sensor. The safety device for blocking leakage current according to an embodiment of the present invention may further include a smart coupling circuit breaker (500) which is equipped with a function to branch into a grounding path, a measurement path, and a load path of the isolation transformer, and a function to cut off the supply of current by an interrupt from a leakage current analyzer or an administrator. Effects of the invention

[0012] The present invention can prevent electric shock, power outage, or fire accidents by using an isolation transformer, a current limiting means, and a grounding means together to supply a microcurrent to a load within the permissible limit for electric shock. Brief explanation of the drawing

[0013] Figure 1 illustrates an example of supplying electricity directly from an electric power source to a load. Figure 2 illustrates an example of supplying electricity from an electric power source to a load using the safety device of the present invention. FIG. 3 is a block diagram illustrating a safety device according to an embodiment of the present invention. Figure 4 is an example illustrating the operating principle of an isolation transformer. Figure 5 is a block diagram illustrating the safety device of Figure 3 in detail. Figure 6 is an example illustrating the operating principle regarding frequency modulation compensation. Figure 7 is an example illustrating the use of a video current transformer. Figure 8 is an example of a code representing the phenomenon according to the degree of electric shock to the human body. Figure 9 is an example illustrating the path and components of a leakage current. Figure 10 is an example illustrating the relationship between resistive and capacitive currents. Figure 11 illustrates an example of calculating a resistive current. Figure 12 is an example illustrating the screen of a leakage current analyzer. Figure 13 is an example illustrating the function of a leakage current analyzer. Figure 14 is an example illustrating the specifications of a microcontroller. FIG. 15 is an example illustrating a current limiting means (900). Specific details for implementing the invention

[0014] Embodiments of the present invention will be described in detail below with reference to the attached drawings and the contents described therein, but the present invention is not limited or restricted by the embodiments.

[0015] FIG. 2 illustrates an example of supplying electricity from an electric power source to a load using the safety device of the present invention, wherein the safety device (10) is formed between the electric power source and the load and can control the current supplied to the load so that an electric shock accident does not occur even in the current-carrying area.

[0016] FIG. 3 is a block diagram illustrating a safety device according to an embodiment of the present invention, comprising an isolation transformer (100), a measuring means (200), a control means (800), a current limiting means (900), and a grounding means (300).

[0017] FIG. 4 illustrates an example of the operating principle of an isolation transformer, wherein the isolation transformer (100) is called an Isolation Transformer and is connected to an electrical power source on the input side. The isolation transformer (100) can transfer electrical energy from one circuit to another without physical contact. The isolation transformer (100) operates in a magnetic induction manner, using a magnetic field to induce an electromotive force in another circuit without affecting the frequency.

[0018] The isolation transformer (100) can reduce the risk of electrical shock and fire by providing an electrically isolated circuit, and is particularly useful when used in high-voltage devices or high-current systems, and can improve electrical safety.

[0019] The isolation transformer (100) can prevent or reduce the transmission of external voltage fluctuations or noise, thereby improving power quality and acting as an important factor, especially in sensitive electronic equipment or communication systems.

[0020] The isolation transformer (100) can provide a safe power supply even when the system is not properly grounded, thus solving the grounding problem. Additionally, the isolation transformer (100) is useful in systems requiring electrically isolated power supply between circuits by providing electrically isolated operation between multiple circuits.

[0021] Accordingly, the isolation transformer (100) can be used to provide protection against electric shock, reduce EMI and noise, and resolve electrical isolation and grounding issues. The specifications applied to the isolation transformer (100) in the present invention are as follows. The input voltage is 220V, the rated frequency is 60Hz, the output voltage is 220V, and the rated current is variable.

[0022] The isolation transformer (100) can electrically isolate the input side and the output side to eliminate the voltage difference between the two sides, so there is a high probability that the output side will not receive an electric shock even if a user makes electrical contact. However, several additional measures are required to ensure a non-electric shock state.

[0023] For example, it is important to check the insulation status of electrical equipment and provide proper grounding, and attention must be paid to electrical safety when using the isolation transformer (100). Although the isolation transformer (100) itself may provide a non-shocked state, other electrical equipment may still be at risk of electric shock. Accordingly, the grounding means (300) can provide grounding with various electrical equipment, such as the measuring means (200), to provide a safe environment.

[0024] The grounding means (300) can provide Class 2 grounding or Class 3 grounding, and in the case of Class 3 grounding, it can be provided in the FG (Frame Ground) method. FG provides a safe electrical path to the structure and frame in the electrical system to prevent external leakage of voltage or current, and plays an important role in ensuring the safety of the system and compliance with safety regulations by discharging leakage current to the ground in the event of an electrical abnormality.

[0025] FIG. 5 is a block diagram illustrating the safety device of FIG. 3 in detail, wherein the measuring means (200) measures the state of the isolation transformer. The measuring means (200) may include a frequency modulation compensation unit (210) and a video current transformer (220).

[0026] FIG. 6 illustrates an example of the operating principle regarding frequency modulation compensation, wherein the frequency modulation compensation unit (210) compensates for the output side frequency of the isolation transformer. The frequency modulation compensation unit (210) can block leakage current caused by frequency fluctuations, can correct to 60Hz, and can operate in conjunction with the control means (900) so that a signal is supplied to the load at the corrected frequency.

[0027] The frequency modulation compensation unit (210) can correct the phenomenon where the frequency may fluctuate due to the difference between the input and output of the isolation transformer (100) and reduce the fluctuation of the load.

[0028] The frequency modulation compensation unit (210) can compensate for the frequency to convert the frequency to a constant amplitude without external interference, thereby ensuring that there is no potential difference due to electronic arrangement. The frequency modulation compensation unit (210) can operate according to Kirchhoff's current law, which states that at a branching point (a point where lines are connected or meet) through which current flows, the sum of the currents, that is, the sum of the amount of incoming current and the amount of outgoing current, is equal.

[0029] The frequency modulation compensation unit (210) can operate on the principle of detecting abnormal conditions of applied (voltage, current) using wavelength bands based on the equipotential phenomenon between each phase and compensating the frequency with a frequency compensation control device, and can prevent electric shock accidents by shielding, absorbing, and reducing leakage current, and can shield against external surges.

[0030] FIG. 7 illustrates an example of the use of a zero-sequence current transformer, wherein the zero-sequence current transformer (220) is equipped with a function to measure the output side current of an isolation transformer (100). The zero-sequence current transformer (220) can be used to detect ground fault current. The zero-sequence current transformer (220) detects zero-sequence currents, such as unbalanced currents in each phase, in the event of a ground fault and transmits a microcurrent proportional to this to the secondary side, with the rated zero-sequence primary current being 200mA and the rated zero-sequence secondary current being 1.5mA.

[0031] The control means (800) generates a current limit value by comparing the measured value generated using the measuring means (200) with the reference value. The reference value can be classified by the capacity of the load and is a value used to calculate a current limit value that can supply a microcurrent of the permissible electric shock limit to the load.

[0032] Figure 8 is an example of a code representing the phenomenon according to the degree of electric shock to the human body. The permissible electric shock level refers to a level where there is no reaction or harmful physiological effects even if the human body is electrocuted, and can be represented by AC-1 and AC-2 codes.

[0033] AC-3 is a level where there is a possibility of spasmodic muscle contraction or respiratory distress if the current continues to flow for more than 2 seconds, and AC-4 is a level that causes pathophysiological symptoms such as cardiac arrest, respiratory arrest, or severe burns. AC-4-1 is a probability of ventricular fibrillation of 5% or less, AC-4-2 is about 50% or less, and AC-4-3 is about 50% or more.

[0034] FIG. 9 illustrates an example showing the path and components of a leakage current, wherein the control means (800) may include a leakage current analyzer (810) and a microcontroller (820). The leakage current analyzer (810) receives a signal value from the frequency modulation compensation unit (210) and operates in conjunction with it, generates a correction value by comparing a measurement value using a video current transformer (220) with a set reference value, and can generate an alarm when a measurement value exceeding the set reference value is received.

[0035] The leakage current analyzer (810) can operate in conjunction with the frequency modulation compensation unit (210) to block the increase in leakage current when the value changes based on a 60Hz frequency, and can self-control the load by classifying it according to load fluctuations, and can perform self-control by the microcontroller (820). The current limiting means (900) or the microcontroller (820) may be equipped with a bypass function to control self-control and the supply of microcurrent together.

[0036] The microcontroller (820) stores reference values ​​for IGR and IGC values ​​according to the capacity of the load, and generates a variable current limit value using the correction value generated by the leakage current analyzer in real time.

[0037] Leakage current is classified into resistive, capacitive, and inductive types. Resistive leakage current can occur due to insulation degradation. Although power lines are designed and installed with sufficient insulation values ​​in accordance with electrical installation standards during initial construction, degradation can occur due to surges, lightning strikes, abnormal voltages, arcs such as corona discharge, and temperature and humidity. Additionally, resistive leakage current can result from lax facility management, damage to cable or wire sheathing during work, or exposure of the conductor to moisture.

[0038] In underground lines, capacitance may occur between the conductor and the ground, which can cause capacitance leakage current. Additionally, capacitance leakage current can occur when inductors and capacitors are used in the electromagnetic interference (EMI) filter section of the electrical and electromagnetic system, and the capacitor connected to ground filters high-frequency noise generated during AC-DC conversion. Furthermore, capacitance leakage current can be caused by the capacitance of the semiconductor on the PCB and the grounded heat sink, as well as the capacitance present in the primary and secondary coils of the isolation transformer (100).

[0039] Inductive leakage current can occur due to various factors such as insulation failure between inductor windings, parasitic capacitance, and residual magnetic flux, and excessive leakage current causes energy loss.

[0040] Figure 10 illustrates an example of the relationship between resistive and capacitive currents. The resistive current (IGR) is a phase-in component with the voltage and represents the flow of deterioration in the insulation resistance of electrical products connected to the power line. The capacitive current is caused by the capacitance between the power line and the ground and is a relatively small displacement current that causes fatal electric shock and electrical fires.

[0041] Regarding the issue of electric shock, capacitance is often ignored because the charging voltage is used as an instantaneous starting current when the machine is operated during continuous use of the device, but it can be particularly vulnerable to fire and cause damage to the human body due to static electricity generation, and can be caused by the capacitance present in the primary and secondary coils of the isolation transformer (100). Therefore, in the present invention, the current limit value is calculated by considering both resistance and capacitance.

[0042] FIG. 11 illustrates an example of calculating a resistive current, wherein the measuring means (200) may further include means for detecting current or voltage, such as a CT or PT, in addition to a current transformer (220). The control means (800) may further include means for amplifying the leakage current, calculating the phase difference, and calculating the amount of the leakage current.

[0043] The safety device (10) may further include a communication means (600). The communication means (600) may provide data from the measurement means (200) to the control means (800). The communication means (600) may use 4-digit RS485 communication and may include a Wi-Fi transmission and reception function.

[0044] The measuring means (200) may further include a power factor controller (230), a frequency meter (240), a temperature sensor (240), and a temperature controller (250). The power factor controller (230) is formed at the rear end of the frequency modulation compensation unit (210) and the image current transformer (220) to control the power factor of the output of the isolation transformer (100). The power factor controller (230) can control the power factor power between voltage and current. The frequency meter (240) provides a numerical value regarding frequency and can be linked with the communication means (600).

[0045] The isolation transformer (100) may generate heat during operation, and if the heat is not continuously controlled, performance may deteriorate or there may be a risk of fire; therefore, the heat must be reduced when it is generated. A temperature sensor (240) measures the temperature of the isolation transformer (100), and a temperature controller (250) can control the temperature of the isolation transformer (100) based on the measurement value of the temperature sensor (240). The temperature controller (250) may be a ventilation fan, such as a fan, and may be operated according to the control of the control means (800).

[0046] FIG. 12 is an example illustrating the screen of a leakage current analyzer, and FIG. 13 is an example illustrating the function of a leakage current analyzer. The leakage current analyzer (810) receives digital signals for IGR, IGC, IO, GR, Freq, and Volt values, compares the measured value with a set reference value to generate a correction value, and can generate an alarm when a measured value exceeding the set reference value is received.

[0047] FIG. 14 is an example illustrating the specifications of a microcontroller, which can be configured with multiple channels to generate a correction value based on the capacity of the load or to generate a variable current limit value.

[0048] FIG. 15 illustrates an example of a current limiting means (900), wherein the current limiting means (900) can operate in a semiconductor manner, can operate in a variable manner such as from 0 to 10A, and can operate in an internal current sensing resistor manner when current passes through.

[0049] The current limiting means (900) can variably limit the current to a level of electric shock that is not harmful to the human body, such as from 0.5uA to 1uA, and can prevent electric shock, power outage, and fire accidents by allowing the limited microcurrent to flow to the load.

[0050] The safety device (10) may further include a smart combined circuit breaker (500) which is equipped with a function to divide and branch into a ground path, a measurement path, and a load path of the isolation transformer (100), and a function to cut off the supply of current by means of an interrupt from a leakage current analyzer (810) or an administrator.

[0051] The present invention can integrally control each path for the output of an isolation transformer (100) using a smart coupling circuit breaker (500), thereby enabling the measuring means (200), the control means (800), and the current limiting means (900) to operate stably and effectively prevent electric shock, power outage, or fire accidents.

[0052] The smart combined circuit breaker (500) has a very high utility as it has the ability to block abnormal current supply in addition to the function of controlling the path.

[0053] The present invention has a standard value set for each load capacity such as 3K, 5K, and 7K, and a method of limiting the current supplied to the load according to the capacity accordingly, so it can efficiently provide path control by the isolation transformer (100) and the smart coupling circuit breaker (500).

[0054] In addition, the present invention can further enhance safety by analyzing not only resistive but also capacitive leakage currents in addition to the isolation transformer (100) to generate a current limit value accordingly, applying leakage current effects due to frequency correction, and eliminating electrical risk factors of each means due to grounding. Explanation of the symbols

[0055] 10: Safety device 100: Isolation transformer 200: Measuring means 210: Frequency modulation compensation unit 220: Video Current Transformer 230: Power Factor Controller 235: Frequency meter 240: Temperature sensor 250: Thermostat 500: Smart-integrated circuit breaker 600: Communication means 700: Grounding means 800: Control means 810: Leakage current analyzer 820: Microcontroller 900: Current limiting means

Claims

Claim 1 An isolation transformer (100) connected to an electrical power source on the input side; a measuring means (200) for measuring the state of the isolation transformer; a control means (800) for generating a current limit value by comparing a measured value generated using the measuring means with a reference value; a current limiting means (900) equipped with a function to limit the current according to the capacity of the load and supplying a microcurrent of permissible electric shock to the load using the current limit value; and a grounding means (300) for providing grounding with the measuring means, wherein the isolation transformer, the current limiting means, and the grounding means are used together to prevent electric shock accidents and power outages, wherein the measuring means includes a frequency modulation compensation unit (210) that compensates for the output side frequency of the isolation transformer and a zero-sequence current transformer (220) that measures the output side current of the isolation transformer, and the control means includes a leakage current analyzer (810) that receives the signal value of the frequency modulation compensation unit and operates in conjunction with it, generates a correction value by comparing a measured value using the zero-sequence current transformer with a set reference value, and generates an alarm when a measured value exceeding the set reference value is received, and an IGR value and according to the capacity of the load A safety device for blocking leakage current, characterized by further including a microcontroller (820) that stores a reference value for an IGC value and generates a variable current limit value using a correction value generated in real time from a leakage current analyzer, wherein the measuring means includes a power factor controller (230) formed at the downstream end of the frequency modulation compensation unit and the image current transformer to control the power factor; a temperature sensor (240) that measures the temperature of the isolation transformer and a temperature controller (250) that controls the temperature of the isolation transformer based on the measurement value of the temperature sensor, and further including a smart coupling circuit breaker (500) that is equipped with a function to branch into a ground path, a measurement path, and a load path of the isolation transformer and is equipped with a function to cut off the supply of current by an interrupt from a leakage current analyzer or an administrator. Claim 2 delete Claim 3 delete

Images