Ground potential safety voltage maintaining system (main distribution board, sub distribution board, control panel, and transformer panel) in case of direct or indirect contact (ground fault or electric leakage) and control method thereof

Abstract

A ground potential safety voltage maintaining system in case of direct or indirect contact (ground fault or electric leakage) according to the present invention includes a fault detector electrically connected to a power supply unit to transmit AC or DC electricity from the power supply unit to a load facility and configured to detect a decrease in insulation resistance between the ground and at least one of neutral points having a potential between voltages of two or more power lines or a decrease in the magnitude of leakage current or ground potential, wherein the fault detector operates to ground a safety voltage maintaining switch to the ground through a safety voltage maintaining element so that the ground potential becomes a safety voltage or less, the switch being connected to the power line or the neutral point corresponding to a case where the decrease in the insulation resistance, the increase in the leakage current, or the decrease in the ground potential, which has a value equal to or greater than a predetermined value, occurs among the two or more power lines and the neutral points.

Description

Ground potential safety voltage maintenance system (distribution board, distribution board, control board, transformer board) and its control method in case of direct or indirect contact (ground fault, leakage current)

[0001] The present invention relates to a system for maintaining a safe voltage to ground potential in the event of direct or indirect contact (ground fault, leakage current), and more particularly, to a system for maintaining a safe voltage to ground potential in the event of direct or indirect contact (ground fault, leakage current), which limits leakage current between a power line transmitting alternating or direct current and the ground to test or detect a change in insulation resistance or ground potential or leakage current, and grounds or releases the ground of a power line in which an increase or decrease has occurred based on a predetermined set value to the ground through a device for maintaining a safe voltage, thereby lowering the ground potential of a faulty power line below a safe voltage and fundamentally preventing leakage current from flowing to a human body, causing an electric shock, or causing an electrical fire, and a control method thereof.

[0002] Among electrical accidents, electric shock accidents, which directly cause damage to the human body, occur when current flowing through a person from one phase of the power supply passes to another phase or to ground. As outlined in KS C IEC TS 60479-1 (Effects of electric current on humans and livestock - Part 1: General aspects), when the electric shock current flowing through a person exceeds a certain hazardous current, injury or death can occur.

[0003] In particular, if a leakage current or ground fault occurs in a power line and the leakage current flows from the power line to the ground and passes through the human body, an electric shock accident may occur, and if it flows through surrounding equipment or combustibles, the equipment may be damaged or an electrical fire may occur, causing serious casualties.

[0004] In the case of an electric shock accident, it is known that if the current flowing to the human body is generally 15mA or more, it causes convulsions (pain), and if it is 50mA or more, it can lead to death. Therefore, in order to prevent electric shock accidents, the electric shock current should be 15mA or less, which is below the dangerous current, and preferably, the ground potential of the power line through which the leakage current flows should be 30V or less, which is the safe voltage stipulated by law in Korea. Internationally, it is necessary to configure electrical equipment and distribution lines so that the ground potential is 20-50V or less.

[0005] Electric shock and fire accidents caused by leakage current in the event of a current leak or ground fault can occur when electrical equipment is deteriorated or damaged, a human body or a flammable object comes into contact with one or more phases of a power line or outlet with its insulation peeled off, or when leakage current generated by submersion of a power line, terminal block, or electrical equipment flows to the ground through a human body or flammable objects such as dust or oil.

[0006] However, existing circuit breakers that block leakage current caused by direct or indirect contact of the human body with a live part, or by ground fault or leakage current, have limitations in fundamentally preventing electrical accidents caused by leakage current because even when direct or indirect contact, ground fault or leakage occurs, leakage current flows without restriction while the circuit breaker operates, and leakage current is detected only when it exceeds a certain value and the circuit breaker operates, or even when leakage current is limited to below a dangerous current, electric shock or fire can be caused by a small amount of leakage current.

[0007] In addition, in order to prevent electrical accidents due to aging and damage of electrical equipment, it is difficult for electrical safety managers to conduct visual inspections and other tests on an ongoing basis. Therefore, it is necessary to allow regular inspections by the general public or to automatically check and notify the insulation status of electrical equipment on an ongoing basis to prevent electrical accidents that occur in advance.

[0008] In order to solve various problems caused by leakage current due to such ground faults and leakage currents, a previously proposed technology is disclosed in the Korean Intellectual Property Office, Patent Gazette, Registration No. 10-2628733 ((Registered on January 23, 2024) (Title of invention: Device for preventing electric shock in case of leakage current and ground faults and distribution system equipped therewith) (hereinafter referred to as “Prior Art 1”)).

[0009] The disclosed 'Previous Technology 1' is,

[0010] A power supply unit is electrically connected to a power supply unit to transmit alternating current or direct current from the power supply unit to a load facility, and comprises two or more power lines insulated from the ground with a resistance value higher than a predetermined grounding resistance value, and a fault detector configured to detect whether a leakage current occurs between at least one neutral point having a potential between the voltages of the two or more power lines and the ground, wherein the fault detector is configured to ground the power line or neutral point where the leakage current occurs among the two or more power lines and the neutral point to the ground when a leakage current occurs.

[0011] However, the above conventional technology has a problem that when a leakage current occurs and the power line where the leakage current occurred is grounded to the ground, a ground fault or short circuit or a fire may occur due to the leakage current if a leakage current occurs in another circuit at the same time, or the leakage current may flow to the human body and cause an electric shock.

[0012] In addition, when a power line with a leakage current is grounded to the ground, there is a problem that if a leakage current occurs in another circuit at the same time, the two circuits will switch, causing the power lines to short each other, damaging electrical equipment, or causing an electrical fire due to a short-circuit spark.

[0013] In addition, if a detection malfunction occurs when a leakage current occurs, there is a problem that electric shock may occur due to the power line where no leakage current has occurred being grounded to the ground, or an electrical accident may occur due to a short circuit or fire, resulting in personal injury.

[0014] In addition, when checking whether the insulation of electrical equipment is functioning normally, it is safe to do so in a power outage, but there was a problem in that an electrical safety manager had to test whether the fault detector and system circuit were functioning normally in a live state, and in order to do that test, he had to take the risk of electrical accidents such as electric shock, short circuit, and spark.

[0015] Accordingly, the present invention has been devised to solve the problems of the prior art, and the purpose of the present invention is to provide a system for maintaining a safe voltage to ground in the event of direct or indirect contact (ground fault, leakage current) that can fundamentally prevent leakage current from flowing to the human body and causing an electric shock or leakage current from flowing to the ground, by grounding a faulty power line to the ground through a safety voltage maintaining element preset according to the supply voltage so that when a leakage current occurs, the ground potential of the power line where the leakage current has occurred is maintained below a safe voltage, thereby preventing the leakage current from flowing to the ground and causing an electrical fire.

[0016] In addition, the purpose of the present invention is to provide a system for maintaining ground potential safety voltage in case of direct or indirect contact (ground fault, leakage current) that allows a person to test ground potential and leakage current without an electrical accident even in a live state to determine whether the circuit of the present invention operates normally.

[0017] In addition, the purpose is to provide a ground potential safety voltage maintenance system in case of direct or indirect contact (ground fault, leakage current) that can fundamentally prevent electrical accidents such as short circuits from occurring by a safety voltage maintenance element even if a fault occurs simultaneously in a power line other than the power line where the leakage current occurred.

[0018] In addition, the purpose is to provide a system for maintaining ground potential safety voltage in case of direct or indirect contact (ground fault, leakage current) that can fundamentally prevent electrical accidents such as short circuits by eliminating the electrical path of all circuits connected between the power line other than the power line where the leakage current occurred and the ground when a leakage current occurs, thereby eliminating the ground potential of the faulty power line and preventing the occurrence of leakage current, and notifying it wired or wirelessly.

[0019] In addition, the purpose is to automatically and continuously monitor the insulation status of all electrical equipment (electrical, mechanical devices and load equipment such as transformers, distribution panels, control panels, distribution panels, circuit breakers, motors, power lines, outlets, etc., home appliances, etc.) connected to the system circuit of the present invention, and to detect and notify wired or wirelessly when the insulation resistance decreases above a predetermined standard, or the ground potential fluctuates, or the leakage current exceeds a set standard, and to promptly take follow-up measures, thereby preventing electrical accidents at the source.

[0020] In addition, the purpose is to prevent electrical accidents at the source by commercializing the test section of the present invention as a separate device and generating changes in impedance, etc. in grounding systems other than the IT grounding system (non-grounding system) of the present invention to check whether existing leakage circuit breakers, etc. operate normally due to leakage current.

[0021] The technical problems to be solved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0022] In order to achieve the above object, the system for maintaining the ground potential safety voltage in case of direct or indirect contact (ground fault, leakage current) according to the present invention is electrically connected to the power supply unit to transmit AC or DC electricity from the power supply unit to the load equipment, and one or more fault detectors configured between the power line of the TN grounded distribution system or the IT grounded distribution system and the neutral point having a potential between the voltages of the two or more power lines and the ground, constantly monitor the quality of electricity, and a test switch connected to at least one end of the power line is connected in series to one end of one or more test elements so that the other end of the test elements is grounded, and the test switch is operated to test the variation of the insulation resistance or leakage current or ground potential, and perform an inspection for a reference set value through the fault detector, or detect a decrease in the insulation resistance or the leakage current size or the ground potential between at least one of the neutral points having a potential between the voltages of the two or more power lines electrically connected to the power supply unit and the ground. Including, the fault detector is characterized in that, when a decrease in the insulation resistance or an increase in the leakage current or a decrease in the ground potential occurs by a predetermined set value or more among the two or more power lines and the neutral point, the safety voltage maintenance switch connected to the power line or the neutral point is grounded to the ground through a safety voltage maintenance element so that the ground potential becomes lower than the safety voltage, or when the fault detector detects a decrease in the insulation resistance or a decrease in the ground potential or a leakage current between the power line and the ground and detects a value higher than the predetermined set value, the ground release switch is operated to disconnect all circuits electrically connected between the power line and the ground, thereby preventing and removing the occurrence of the ground potential and the leakage current, and the fault detector detects a fault state of the power line and notifies it wired or wirelessly.

[0023] The system for maintaining a safe voltage to ground potential in case of direct or indirect contact (ground fault, leakage current) according to the present invention is such that the fault detector is electrically connected between at least one of the two or more power lines and the neutral point and the ground to detect the power quality and insulation status of at least one of the power lines, the neutral line, the neutral point, and the ground, and perform at least one of alarm, notification, monitoring, control, blocking, and restoration, wired or wirelessly.

[0024] The system for maintaining a safe voltage to ground potential in case of direct or indirect contact (ground fault, leakage current) according to the present invention may further include a safe voltage maintenance switching unit controlled to ground a power line or neutral point in which a decrease in insulation resistance, a decrease in ground potential, or a leakage current has occurred among the two or more power lines and neutral points by short-circuiting the power line or neutral point to the ground through a safe voltage maintenance element, based on the detection result of the fault detector.

[0025] The ground potential safety voltage maintenance system according to the present invention in case of direct or indirect contact (ground fault, leakage current) may include: the fault detector may include two or more fault detectors each electrically connected between the two or more power lines and the ground; and the safety voltage maintenance switching unit may include two or more safety voltage maintenance switches whose turn-on or turn-off is controlled in response to each of the two or more fault detectors.

[0026] The ground potential safety voltage maintenance system in case of direct or indirect contact (ground fault, leakage current) according to the present invention is characterized in that at least one of the two or more safety voltage maintenance switches is a normally open (NO) type switch that is turned on when an operating current exceeding a predetermined reference value flows to a corresponding fault detector, and can be electrically connected to at least one of the power lines and neutral points other than the power line to which the corresponding fault detector is connected among the two or more power lines and neutral points.

[0027] The system for maintaining a ground potential safety voltage in case of direct or indirect contact (ground fault, leakage current) according to the present invention is such that at least one of the two or more safety voltage maintenance switches is a normally open (NO) type switch that is turned on when the insulation resistance of the corresponding fault detector decreases by a predetermined reference value or the ground potential decreases, and can be electrically connected to at least one of the safety voltage maintenance elements connected to the power line and neutral point where the insulation resistance decreases or the ground potential decreases among the two or more power lines and neutral points.

[0028] The ground potential safety voltage maintenance system in case of direct or indirect contact (ground fault, leakage current) according to the present invention is characterized in that at least one of the two or more safety voltage maintenance switches is a normally closed (NC) type switch that is turned off when an operating current exceeding a predetermined reference value flows to a corresponding fault detector, and is electrically connected in series with a safety voltage maintenance element to the corresponding fault detector and can be connected in parallel with the safety voltage maintenance element.

[0029] The system for maintaining a safe voltage to ground potential in case of direct or indirect contact (ground fault, leakage current) according to the present invention may include a fault detector, a current detection unit for limiting the leakage current to a predetermined dangerous current or lower, or a voltage detection unit for detecting the ground potential between the power line and the ground while maintaining the ground voltage of the faulty power line at a safe voltage and detecting the leakage current.

[0030] The ground potential safety voltage maintenance system in case of direct or indirect contact (ground fault, leakage current) according to the present invention may include a fault detector, a current detection unit that limits the leakage current to a predetermined dangerous current or less and detects the leakage current; and a unidirectional current unit that limits the path of the leakage current so that the leakage current flows in one direction through the current detection unit.

[0031] The system for maintaining a ground potential safety voltage in case of direct or indirect contact (ground fault, leakage current) according to the present invention further includes a circuit breaker configured to open and close an electrical connection between the power line and a load, and the fault detector can control the circuit breaker to cut off the electrical connection between the load and the power line when a leakage current occurs in two or more of the power lines.

[0032] According to the present invention, a system for maintaining a safe voltage to ground potential in case of direct or indirect contact (ground fault, leakage current) is provided, wherein the load unit is a three-phase AC power source including an R phase, an S phase, and a T phase, and the fault detector includes first to third fault detectors respectively connected between the R phase, the S phase, and the T phase and the ground, and the safety voltage maintenance switching unit includes first to third safety voltage maintenance switches corresponding to the first to third fault detectors respectively and turned on when an operating current exceeding a predetermined reference value flows to the corresponding fault detector or when the ground potential decreases, wherein the first to third safety voltage maintenance switches can be installed between the plurality of power lines and the ground through a safety voltage maintenance element in order to maintain a safe voltage of the ground potential of the corresponding power line when a leakage current or ground fault occurs in any one of the plurality of power lines connected to the R phase, the S phase, and the T phase.

[0033] According to the present invention, a system for maintaining a ground potential safety voltage in the event of direct or indirect contact (ground fault, leakage current) is provided, wherein the load unit is a three-phase AC power source including an R phase, an S phase, and a T phase, the fault detector includes first to third fault detectors respectively connected between the R phase, the S phase, and the T phase and the ground, and the safety voltage maintenance switching unit includes first to third safety voltage maintenance switches corresponding to the first to third fault detectors respectively and turned off when an operating current greater than a predetermined reference value flows to the corresponding fault detector, wherein the first to third safety voltage maintenance switches can be installed between the other end of the safety voltage maintenance element connected to the plurality of power lines and the ground so that when a leakage current or ground fault occurs in one or more of the plurality of power lines connected to the R phase, the S phase, and the T phase, the corresponding power line is grounded to the ground through the safety voltage maintenance element.

[0034] The ground potential safety voltage maintenance system according to the present invention in case of direct or indirect contact (ground fault, leakage current) is configured such that the test switch is connected by any one of a plug, a clamp, a terminal, and a clip, and can be installed as a selector switch or cam switch capable of electrically selecting any one of the two or more connected power lines.

[0035] In the system for maintaining a ground potential safety voltage in case of direct or indirect contact (ground fault, leakage current) according to the present invention, the test element is composed of at least one of a resistor, a capacitor, an inductor, and a diode, and any one of the test elements is connected to a selector switch or cam switch that can electrically select the test element, so that the test switch can be connected.

[0036] The system for maintaining a ground potential safety voltage in the event of direct or indirect contact (ground fault, leakage current) according to the present invention further includes a surge protector electrically connected between the ground and at least one of the two or more power lines and a neutral point having a potential between the voltages of the two or more power lines, and can detect a defect, deterioration, or insulation failure of the surge protector.

[0037] In order to achieve the above purpose, the control method of the ground potential safety voltage maintenance system in case of direct or indirect contact (ground fault, leakage current) according to the present invention is as follows.

[0038] A step of supplying power to the power line (410, 420, 430, N) and the load (900);

[0039] A step of setting a predetermined setting value for ground potential, leakage current or insulation resistance in a fault detector (210);

[0040] The above fault detector (210) is characterized by including a step of detecting the quality of electricity (voltage, current, reactive power, apparent power, active power, power amount, ground potential, leakage current, frequency, power factor, etc.) of the supplied power and monitoring it wired or wirelessly; a step of comparing the detected quality of electricity and a reference set value with a predetermined reference set value, and a step of operating a safety voltage maintenance switch (310, 320, 330) connected to a power line (410, 420, 430) or a neutral point (N) in the case of a decrease in insulation resistance, a change in ground potential, or the occurrence of a leakage current, and grounding it to the ground through a safety voltage maintenance element (311, 321, 331); and a step of operating a circuit breaker (500) to cut off the power supplied to a load (900) and notifying it wired or wirelessly in the case of there being two or more detected results by the fault detector (210).

[0041] The system for maintaining a safe voltage to ground potential in the event of direct or indirect contact (ground fault, leakage current) according to the present invention detects whether there is a leakage current or a change in ground potential between a power line or a neutral line transmitting AC or DC electricity and the ground, and when a leakage current or a change in ground potential occurs, the ground potential of the power line or neutral line through which the leakage current flows or the change in ground potential occurs is grounded to the ground through a safety voltage maintaining element so as to maintain a safe voltage, thereby preventing the leakage current from flowing to the ground and causing a fire or an electric shock to a human body.

[0042] In addition, the ground potential safety voltage maintenance system in case of direct or indirect contact (ground fault, leakage current) according to the present invention has the effect of preventing electric shock or fire caused by ground fault or leakage current by detecting a change in ground potential occurring in one or more lines or detecting leakage current caused by ground fault or leakage current and fundamentally preventing leakage current from flowing to the outside.

[0043] In addition, the ground potential safety voltage maintenance system in case of direct or indirect contact (ground fault, leakage current) according to the present invention has the effect of allowing simple and safe testing and inspection of whether the circuit according to the present invention operates normally without risk.

[0044] In addition, the ground potential safety voltage maintenance system in case of direct or indirect contact (ground fault, leakage current) according to the present invention automatically detects changes in insulation resistance of circuits such as transformers, circuit breakers, power lines, and load equipment of the system according to the present invention, and automatically detects when it reaches or exceeds a predetermined set value, thereby having the effect of taking action before an electrical accident (electric shock, fire, burnout, power outage, etc.) occurs.

[0045] FIG. 1 is a wiring diagram showing the configuration of a ground potential safety voltage maintenance system in case of direct or indirect contact (ground fault, leakage current) according to one embodiment of the present invention.

[0046] Figure 2 is a block diagram showing the internal blocks of a fault detector according to the present invention.

[0047] FIG. 3 is a conceptual diagram for explaining the operation in a normal state in one embodiment of the present invention illustrated in FIG. 1.

[0048] FIG. 4 and FIG. 5 are conceptual diagrams for explaining the operation when a charging part of one phase is contacted or a leakage current or ground fault occurs in one embodiment of the present invention.

[0049] Figure 6 is a conceptual diagram for explaining the operation when a leakage current or ground fault occurs in two phases in one embodiment of the present invention.

[0050] Fig. 7 is a wiring diagram showing the configuration of a ground potential safety voltage maintenance system in case of direct or indirect contact (ground fault, leakage current) according to another embodiment of the present invention.

[0051] FIG. 8 is a conceptual diagram for explaining the operation when a charging part of one phase is contacted or a leakage current or ground fault occurs in another embodiment of the present invention illustrated in FIG. 7.

[0052] Figure 9 is a wiring diagram when a configuration capable of performing self-testing in one embodiment of the present invention is applied to a three-phase power supply.

[0053] Figure 10 is a wiring diagram when a configuration according to another embodiment of the present invention is applied to a three-phase power supply.

[0054] Figure 11 is a configuration diagram of a fault detector when applied to a single-phase two-wire, three-phase three-wire, and three-phase four-wire power source in one embodiment of the present invention.

[0055] Fig. 12 is a block diagram of a control method of a ground potential safety voltage maintenance system in case of direct or indirect contact (ground fault, leakage current) according to a preferred embodiment of the present invention.

[0056] Preferred embodiments of the present invention are described in detail with reference to the attached drawings. The following detailed description is merely exemplary and merely illustrates preferred embodiments of the present invention.

[0057] FIG. 1 is a wiring diagram showing the configuration of a ground potential safety voltage maintenance system in case of direct or indirect contact (ground fault, leakage current) according to one embodiment of the present invention.

[0058] Referring to FIG. 1, a system for maintaining a safe voltage to ground potential in the event of direct or indirect contact (ground fault, leakage current) according to the present invention may be configured to include two or more power lines (410, 420) electrically connected to a power supply unit (100) to transmit alternating current or direct current from the power supply unit (100) to a load facility, and insulated from the ground with a resistance value higher than a predetermined ground resistance value, and a fault detector (210) configured to detect a decrease in insulation resistance between at least one of a neutral point (N) having a potential between the voltages of the two or more power lines (410, 420) and the ground, or a change in ground potential, or the occurrence of a leakage current. At this time, the fault detector (210) is characterized in that, when a decrease in insulation resistance, a change (decrease) in ground potential, or a leakage current occurs, the safety voltage maintenance switch (310, 320) operates to ground the power line (410, 420) or neutral point (N) where the ground potential decrease or leakage current occurs among two or more power lines (410, 420) and the neutral point (N) to the ground through the safety voltage maintenance element (311, 321), and when it is necessary to specify the faulty power line, the safety voltage maintenance switch (310, 320) is used to issue an alarm or notify a fault alarm of the corresponding power line where the leakage current has occurred to the fault alarm device (610, 620).

[0059] In addition, according to FIG. 1, it is characterized by including a test switch (710, 720) having one end connected to two or more insulated power lines (410, 420) by a plug, clamp, terminal, clip, etc., and a test element (810, 820) connected in series to the other end of the test switch (710, 720) and grounded to the ground through a ground terminal by a plug, clamp, terminal, clip, etc.

[0060] Here, the other end of the test switch (710) electrically connected to the power line (410) may be selectively connected to one or more of a plurality of test elements (811, 812, 813, 814, etc.) among the test elements (810), and the plurality of test elements may be configured to have impedances such as resistors of different sizes or capacitors of different capacities, and the decrease in insulation resistance occurring in the power line may also be known as a leakage current value detected by a fault detector.

[0061] For example, assuming that the supply voltage is 220 V and the resistance value of the leakage current limiting element (213) is 100 kΩ, if the power line (410) is grounded (grounded) and the insulation resistance value is 0Ω, the leakage current value detected and displayed by the fault detector (210-2) is 0.0022A, or 2.20 mA, according to Ohm's law, and if the power line (410) has a leakage and the insulation resistance value is 50 kΩ, since 220V÷150.000Ω=0.001466A, 1.47 mA is detected and displayed by the fault detector (210-2), and if the insulation resistance value of the power line (410) is 100 kΩ, 1.10 mA is detected and displayed by the fault detector (210-2).

[0062] In addition, whether the human body comes into direct or indirect contact with the charging part, it can be set as a standard for direct and indirect contact using the standard value of human body resistance listed in the literature, and it can be more effective if it is manufactured to separate only the test part or is configured as a separate product so that testing and inspection of the circuit can also be done in other grounding systems.

[0063] In this way, the setting value of the fault detector (210) can be calculated according to the legal standard for monitoring the insulation resistance of the power line (410, 420) according to the size of the supply voltage, and the problem can be solved by inputting the setting value of the leakage current, and by programming the above-described content and inputting only the supply voltage value, the value of the leakage current limiting element (213), and the insulation resistance standard value of the power line in advance into the CPU mounted on the fault detector (210), the procedure for detecting the insulation fault of the power line, maintaining the ground potential below the safe voltage, and notifying it is automatically solved.

[0064] If the fault detector (210) is configured to detect the voltage of the power line and the ground, the ground potential can be set to a predetermined standard value that is 80% or more in the case of a ground fault or 10% or 20% in the case of a current leakage based on the normal ground potential of the power line (410, 420), and the human body can be directly and indirectly contacted by using pork, etc. as mentioned in the Korean Industrial Standard KS CIEC TS 60479-1, to directly contact the live parts of the human body (the live parts of the power line are directly contacted with the pork) and indirect contact (the live parts of the power line are grounded and the pork is indirectly contacted with the exposed conductive part (steel case) and the ground). The standard value for the reduction in the ground potential for electric shock can also be set.

[0065] Here, if the supply voltage of the normal power line (410, 420) is 220V and the ground potential of the power line (410) and the ground (E), and the power line (420) and the ground (E) are each 110V, the case where the power line (410) is grounded is a case where the ground potential decreases by 80%, 110V x 80% = 88V, that is, if the ground potential of the power line (410) decreases to 88V or less, or if the ground potential of the power line (420) increases to 132V or more, the power line (410) is grounded and is set as a predetermined standard, and if it is assumed that the leakage of the power line (410) is a 15% decrease in the ground potential, 110V x 15% = 16.5V, that is, if the ground potential of the power line (410) whose normal ground potential is 110V decreases by 15%, it is 93.5V. If it decreases below this, it is determined that a leakage current has occurred in the power line (410), and a predetermined standard setting value can be set.

[0066] In addition, the reduction in insulation resistance of the power line can be set to a predetermined standard value by a tester. The method is to select the power line (410) with a test switch connected to the power line (410, 420), ground the test element (e.g., 811=25kΩ, 812=50kΩ, 813=100kΩ, 814=200, etc.) of the desired insulation resistance maintenance value of the power line, and input the ground potential value detected by the fault detector (210) as the set value, which becomes the insulation resistance standard set value of the power line. (The legal standard values ​​are 220V 50kΩ and 380V 100kΩ.)

[0067] The power line (410, 420) is a conductor that supplies power from the power supply unit (100) to the load side or the surrounding power equipment (hereinafter referred to as the load equipment), and is a general term for all conductors that are electrically connected to each other and transmit power, including not only separate conductors divided by circuit breakers or switches, but also branch lines that are connected to circuit breakers, switches, or switches, or branch lines that branch off from the main line. At this time, it is preferable that the power line (410, 420) be insulated from the ground so as to have a resistance value higher than a predetermined ground resistance. Here, the insulation is not limited to the case of complete insulation, but includes a case where the power line (410, 420) or the neutral point (N) has a resistance value greater than the normal ground resistance with respect to the ground through grounding work.

[0068] The power supply unit (100) is a component that supplies electricity to the power lines (410, 420), and may be a direct current or alternating current power source. If the power supply is a direct current power source, it may be a charger, solar power, or an ESS (Energy Storage System), and if it is an alternating current power source, it may include a single-phase or three-phase power source, or a multi-phase power source in which the voltage of each phase has a predetermined phase difference. For the convenience of explanation, the following description will be made on the case where the power supply unit (100) is an alternating current power source. In FIGS. 1 to 8, the description will be made based on the single-phase alternating current power source, and in FIGS. 9 to 13, the description will be made on the three-phase alternating current power source. In addition, since the case where the power supply unit (100) is a direct current power source can be configured in the same form as the case where the power supply unit (100) is a single-phase alternating current power source, the description thereof will be omitted.

[0069] The ground potential safety voltage maintenance system in case of direct or indirect contact (ground fault, leakage current) according to the present invention may include a circuit breaker (500) that controls the supply or cutoff of power to a load (900) in conjunction with the detection result of a fault detector (210).

[0070] The circuit breaker (500) can be controlled to separate the load (900) connected to the power supply (100) and the power line (410, 420) from the power line (410, 420) when the fault detector (210) detects that direct or indirect contact of a human body's live part or a ground fault or current leakage has occurred in the power line (410, 420). In particular, the circuit breaker (500) can be controlled to separate the load (900) from the power line (410, 420) when a leakage current has occurred in a plurality of power lines (410, 420) among the power lines (410, 420).

[0071] The fault detector (210) of the present invention can be electrically connected between at least one of two or more power lines (410, 420) and the ground so as to detect whether insulation resistance has decreased, whether ground potential has changed, or whether leakage current has occurred, and to identify the power line (410, 420) or neutral point (N) where the insulation resistance has decreased, the ground potential has decreased, or leakage current has occurred.

[0072] The safety voltage converter according to the present invention may be configured to include a safety voltage maintenance switching unit (300) that is controlled to ground a power line (410, 420) in which a decrease in insulation resistance, a decrease in ground potential, or a leakage current has occurred among two or more power lines (410, 420) through a safety voltage maintenance element (311, 321) based on the detection result of the fault detector (210). Additionally, the safety voltage maintenance switching unit (300) may be configured to ground a neutral point (N) or a neutral line (440) in which a leakage current flows through the neutral point (N) through which a leakage current flows through the safety voltage maintenance element (311, 321) in the case where the power supply unit (100) is a three-phase AC.

[0073] The safety voltage maintenance switching unit (300) is electrically connected to the ground through a safety voltage maintenance element (311, 321) at one end and connected to at least one of two or more power lines (410, 420) or neutral points (N), and the other end is electrically connected to the ground through a safety voltage maintenance element (311, 321), and according to the detection result of the fault detector (210), the power line (410, 420) with reduced insulation resistance or the power line (410, 420) with reduced ground potential or the power line (410, 420) with leakage current or the neutral point (N) is grounded to the ground through the safety voltage maintenance element (311, 321) to maintain the ground potential below the safety voltage, so that instead of the leakage current flowing to the human body, surrounding equipment or load equipment, the safety voltage maintenance switching unit (300) and the safety voltage maintenance element (311, 321) maintain the ground voltage below the safety voltage of 30 V or less. It can fundamentally prevent electric shock and fire.

[0074] Figure 1 illustrates the configuration of a ground potential safety voltage maintenance system in the event of direct or indirect contact (ground fault, leakage current) according to one embodiment of the present invention when the power supply unit (100) is a single-phase alternating current.

[0075] According to FIG. 1, a system for maintaining a ground potential safety voltage in the event of direct or indirect contact (ground fault, leakage current) according to an embodiment of the present invention includes first and second fault detectors (210-1, 210-2) electrically connected between two power lines (410, 420) and the ground, respectively, and a safety voltage maintenance switching unit (300) may include first and second safety voltage maintenance switches (310, 320) whose turn-on or turn-off is controlled in response to each of the fault detectors (210), and a safety voltage maintenance element (311, 321) connected to the safety voltage maintenance switches (310, 320) and grounded to the ground.

[0076] In particular, in the configuration of one embodiment of the present invention, a safety voltage maintenance element (311, 321) connected in series to a safety voltage maintenance switch (310, 320) may be electrically connected in parallel to a corresponding fault detector (210) by the operation of the safety voltage maintenance switch (310, 320). At this time, it is preferable that the safety voltage maintenance switch be a normally close (NC) type switch that is turned off when a decrease in ground potential reaching a predetermined reference set value or a leakage operating current flows to the corresponding fault detector (210).

[0077] If a human body comes into direct or indirect contact with the first power line (410) among the two power lines (410, 420), or if a current leakage or ground fault occurs, the ground potential between the first power line (410) and the ground decreases, so that the detection value of the first fault detector (210-1) that detects the ground voltage between the first power line (410) and the ground reaches a predetermined reference value, and the first fault detector (210-1) operates, so that the first safety voltage maintenance switch (310) is short-circuited. Conversely, when a human body comes into direct or indirect contact with the second power line (420), or when a current leakage or ground fault occurs, the ground potential between the second power line (420) and the ground decreases, so that the detection value of the second fault detector (210-2) that detects the ground voltage between the second power line (410) and the ground reaches a predetermined reference value, and the second fault detector (210-2) operates, so that the second safety voltage maintenance switch (320) is short-circuited.

[0078] Here, leakage current detection is performed when a human body directly or indirectly comes into contact with the first power line (410) among two power lines (410, 420), or when a leakage current or ground fault occurs, the first power line and the ground come into contact, and the voltage of the power line (410, 420) is applied to both ends of the second fault detector (210-2) connected between the second power line (410) and the ground, so that the second fault detector (210-2) having impedance is activated, and thus the first safety voltage maintenance switch (310) connected to the second fault detector is short-circuited. Conversely, when a human body comes into direct or indirect contact with the second power line (410), or when a current leakage or ground fault occurs, the second power line and the ground come into contact, and the voltage of the power line (410, 420) is applied to both ends of the second fault detector (210-2) connected between the second power line (410) and the ground, so that the second fault detector (210-2) having impedance is activated, and thus the first safety voltage maintenance switch (310) connected to the second fault detector is short-circuited.

[0079] The important point here is that when the fault detector detects a decrease in ground potential and operates the safety voltage maintenance switch, and when the fault detector detects leakage current and operates the safety voltage maintenance switch, the configurations must be opposite. That is, when detecting a decrease in ground potential, the ground potential of the power line where the fault occurred decreases, so the fault detector connected to the faulty power line with respect to the ground detects the decreased ground potential. Therefore, in order for the leakage current detection, the fault detector, and the safety voltage maintenance switch to operate in the same manner, both can be configured in the same way if the fault detector detects an increase in ground potential.

[0080] As in one embodiment of the present invention, when the safety voltage maintenance switch is configured as a normally closed (NC) type, detection is possible even if a leakage current or ground fault occurs in a single power line or in multiple power lines.

[0081] FIG. 2 is a block diagram showing the internal blocks of a fault detector (210) that can be used in the present invention.

[0082] The fault detector (210) applied to the ground potential safety voltage maintenance system in case of direct or indirect contact (ground fault, leakage current) according to the present invention is configured to be electrically connected between at least one of two or more power lines and the ground so as to detect whether a change in the ground potential between the power line and the ground or whether a leakage current occurs from the power line to the ground.

[0083] Referring to Fig. 2, each of the fault detectors (210) is characterized by including a current detection unit (211) or a voltage detection unit (211) that detects ground potential or leakage current and outputs a detection signal. At this time, the fault detector (210) may be equipped with a leakage current limiting element (213) whose resistance value at both ends is set to be equal to or greater than a predetermined resistance value so as to limit the leakage current to a predetermined dangerous current or less.

[0084] In addition, as shown in Fig. 2(b), the fault detector (210) may further include a unidirectional current section (212) that limits the path of the leakage current in a predetermined direction so that the leakage current flows in one direction through the current detection section (211) and a leakage current limiting element (213).

[0085] The current or voltage detection unit (211) is a component that detects the ground voltage between the power line and the ground or the leakage current flowing from the power line to the ground, and can detect the change in the ground potential or the leakage current and output a detection signal corresponding thereto. The detection signal may be a signal that the ground voltage decreases or increases below a preset value depending on the supply voltage (220 V, 380 V, etc.), or a signal including information on the magnitude and direction of the leakage current, or a signal outputting whether the leakage current exceeds a preset threshold. The detection signal may be directly provided to a safety voltage maintenance switch or circuit breaker installed on the power line, or may be provided to a separately installed controller (not shown) so as to control the opening and closing of the safety voltage maintenance switch or circuit breaker or output a control signal for an alarm, a fault location indication, or a fault recovery. According to the present invention, the detection signal of the fault detector (210) can be provided as a control signal of the first and second safety voltage maintenance switches (310, 320) so that a power line in which a decrease in ground potential or a leakage current has occurred is selectively grounded to the ground through a safety voltage maintenance element (311, 321).

[0086] In addition, the current or voltage detection unit (211) may further include a leakage current limiting element (213) arranged in series on a current path through which the leakage current flows so that the leakage current is lower than a predetermined dangerous current. At this time, the leakage current limiting element (213) may be configured to include a voltage drop element including a resistance element so as to limit the current value to lower than the dangerous current with respect to the voltage applied to the fault detector (210) when a leakage current occurs. Here, the dangerous current is a current that may cause electric shock to the human body or a fire, and may be appropriately set to be safely adjusted according to the supply voltage of the electrical equipment or the voltage of the ground potential.

[0087] The fault detector (210) according to the present invention may further include a switch whose opening and closing are controlled in conjunction with a detection signal. At this time, the switch is a switch (310, 320) installed between a power line or a neutral point (N) and the ground to maintain a safe voltage, and may perform an operation of grounding the power line to the ground through a safety voltage maintaining element (311, 321), and may be provided as an integral part of the fault detector (210) together with a current or voltage detection unit (211). In this case, the integral switch and the current or voltage detection unit (211) may also be implemented as a solid-state relay (SSR).

[0088] The unidirectional current section (212) is a component that limits the path of the leakage current in a predetermined direction so that the leakage current flows in a unidirectional manner through the current or voltage detection section (211), and may be configured to include a switch element or diode that is controlled to conduct only current in a preset direction, as shown in Fig. 2(b).

[0089] A fault detector (210) configured to include a unidirectional current section (212) is installed between a power line and the ground or between a neutral point (N) and the ground and can operate to detect a power line in which the ground potential fluctuates (decreases or increases) or to identify a power line in which a leakage current flows according to the direction of the leakage current.

[0090] In one embodiment of the present invention, such as in FIG. 1, a fault detector (210) having a structure as shown in FIG. 2(a) may be used, and in another embodiment of the present invention, such as in FIG. 7 and FIG. 8, a fault detector (210) having a structure further including a unidirectional current section (212) as shown in FIG. 2(b) may be used.

[0091] Hereinafter, the configuration and operating principles of one embodiment and another embodiment of the present invention to which the fault detector (210) of the structure of FIGS. 2(a) and 2(b) is applied will be described.

[0092] FIG. 3 is a conceptual diagram for explaining the operation in a normal state in one embodiment of the present invention illustrated in FIG. 1, FIGS. 4 and 5 are conceptual diagrams for explaining the operation in a case where a leakage or ground fault occurs in one power line (410, 420) or one phase, and FIG. 6 is a conceptual diagram for explaining the operation in a case where a leakage or ground fault occurs in multiple power lines (410, 420) or two phases.

[0093] In a system for maintaining a ground potential safety voltage in the event of direct or indirect contact (ground fault, leakage current) according to an embodiment of the present invention, a safety voltage maintenance switch (310, 320) is a normally closed (NC) type switch (310, 320) that is turned off when an operating current exceeding a predetermined reference value flows to a corresponding fault detector (210), and may be configured to be electrically connected in parallel with a safety voltage maintenance element (311, 312) to the same power line (410, 420) as the corresponding fault detector (210). Here, the fault detector (210) can detect when a current below a predetermined reference value flows and control the safety voltage maintenance switch (310, 320) to be short-circuited.

[0094] According to FIG. 3, in a normal state, an operating current exceeding a predetermined reference value flows through the first and second fault detectors (210-1, 210-2), and the first and second fault detectors (210-1, 210-2) respectively control the corresponding first and second safety voltage maintenance switches (310, 320) to open, so that normal power is supplied to the load side (900) through the power line (410, 420).

[0095] If, as shown in Fig. 4(a), a current leakage or ground fault occurs in the first power line (410) among the two power lines (410, 420), the voltage across the first fault detector (210-1) connected between the first power line (410) and the ground drops, and the current flowing to the first fault detector (210-1) becomes lower than a predetermined reference value, so the first safety voltage maintenance switch (310) controlled by the first fault detector (210-1) is short-circuited.

[0096] In this way, when the first power line (410) where a leakage current or ground fault has occurred is grounded to the ground through the safety voltage maintenance element (311) by the first safety voltage maintenance switch (310), the ground potential of the first power line (410) is lowered below the safety voltage by the safety voltage maintenance element (311), and the leakage current 1 that was flowing from the first power line (410) to the ground flows to the ground through the safety voltage maintenance element (311) connected to the first safety voltage maintenance switch (310) as shown in Fig. 4(b) instead of to the human body, surrounding equipment, or flammable objects, so that the ground potential is reduced below the safe voltage, and electrical accidents such as electric shock or fire are fundamentally prevented. (For reference, the safe voltage set in Korea is 30V or less, and the safe voltage in each country is slightly different from 20V to 50V.)

[0097] Conversely, as shown in Fig. 5(a), when a current leakage or ground fault occurs in the second power line (420) among the two power lines (410, 420), the voltage across the two terminals of the second fault detector (210-2) connected between the second power line (420) and the ground drops, so that the current flowing to the second fault detector (210-2) becomes below a predetermined reference value, and thus the second safety voltage maintenance switch (320) controlled by the second fault detector (210-2) is short-circuited.

[0098] In this way, when the second power line (420) in which a leakage current or ground fault has occurred is grounded to the ground through the safety voltage maintenance element (321) by the second safety voltage maintenance switch (320), the ground potential of the second power line (420) is lowered below the safety voltage by the safety voltage maintenance element (321), and the leakage current 2 flowing from the second power line (420) to the ground is reduced to below the safe voltage through the safety voltage maintenance element (311) connected to the second safety voltage maintenance switch (320) instead of to the human body, surrounding equipment, or flammable objects, thereby fundamentally preventing electrical accidents such as electric shock or fire. (The safety voltage maintenance element can be preset to have its value adjusted to be below the safe voltage of 30 V depending on the size of the supply voltage or ground potential.)

[0099] In addition, as illustrated in FIG. 6(a), when a current leakage or ground fault occurs simultaneously in the first and second power lines (410, 420), the current or ground potential flowing through the first and second fault detectors (210-1, 210-2) both become below a predetermined reference value, so that the first and second safety voltage maintenance switches (310, 320) controlled by the first and second fault detectors (210-1, 210-2) can be controlled to be short-circuited. In addition, when a leakage current or ground fault is detected in multiple power lines (410, 420) by the first and second fault detectors (210-1, 210-2), the circuit breaker (500) can be opened as shown in Fig. 6(b) to control the power supply from the power supply unit (100) to the load unit (900) through the power lines (410, 420) to be cut off.

[0100] In a structure such as one embodiment of the present invention, the safety voltage maintenance switch is configured as a normally closed (NC) type so that it is possible to detect a situation in which a leakage current occurs due to a ground fault or leakage current in not only one line of a power line (410, 420) but also a plurality of power lines (410, 420), and in a situation in which a ground fault or leakage current is detected in a plurality of power lines (410, 420), the circuit breaker (500) can be opened and closed to electrically isolate the load (900) from the power line (410, 420).

[0101] Fig. 7 is a wiring diagram showing the configuration of a ground potential safety voltage maintenance system in case of direct or indirect contact (ground fault, leakage current) according to another embodiment of the present invention.

[0102] According to another embodiment of the present invention, a system for maintaining a safe voltage to ground in case of direct or indirect contact (ground fault, leakage current) is characterized in that, unlike the embodiment, when a leakage current or ground fault occurs in a power line (410, 420), an operating current due to a leakage current flows to a fault detector (210) exceeding a predetermined reference value, and the fault detector (210) controls a corresponding safe voltage maintenance switch.

[0103] To this end, in the ground potential safety voltage maintenance system in case of direct, indirect contact (ground fault, leakage current) according to another embodiment of the present invention, the fault detector (210) may be configured to include a unidirectional current section (212) that allows conduction only for leakage current flowing in a specific power line (410, 420), and the safety voltage maintenance switch may be a normally open (NO) type switch that is turned on when an operating current exceeding a predetermined reference value flows in the corresponding fault detector (210). At this time, the safety voltage maintenance switch is characterized in that it is electrically connected to at least one of the power lines (410, 420) and the neutral point (N) other than the power line (410, 420) to which the corresponding fault detector (210) is connected among two or more power lines (410, 420) and the neutral point (N).

[0104] Referring to FIG. 7, a ground potential safety voltage maintenance system in case of direct or indirect contact (ground fault, leakage current) according to another embodiment of the present invention may be configured to include first and second fault detectors (210-1, 210-2) electrically connected between two power lines (410, 420) and the ground, respectively, and first and second safety voltage maintenance switches (310, 320) whose turn-on or turn-off is controlled in response to each of the fault detectors, and a safety voltage maintenance element (311, 312).

[0105] Each of the first and second fault detectors (210-1, 210-2) may be configured to include a current or voltage detection unit (211) that detects a change in ground potential or leakage current, as illustrated in FIG. 2(b), and a unidirectional current unit (212) that limits the path of the leakage current so that the leakage current flows in one direction through the current or voltage detection unit (211).

[0106] In particular, as illustrated in FIG. 7, when the first and second fault detectors (210-1, 210-2) detect only leakage current, if the current conduction direction of the unidirectional current section (212) of each of the first and second fault detectors (210-1, 210-2) is configured to be in the direction of flowing out or inflow from the ground, in a normal state where no leakage or ground fault occurs, no leakage current flows to the fault detector (210), and only when a leakage current occurs in one of the first and second power lines (410, 420), the fault detector (210) detects the leakage current and operates the corresponding safety voltage maintenance switch (310, 320).

[0107] The safety voltage maintenance switch is a normally open (NO) type switch whose contact is short-circuited by a detection signal output when the ground potential decreases to a predetermined reference value or more in the corresponding fault detector (210) or when an operating current flows. In the case of a decrease in the ground potential, the switch is electrically connected to the power line (410, 420) of the corresponding fault detector, and in the case of a leakage current detection, the switch is electrically connected to a power line (410, 420) other than the power line (410, 420) to which the corresponding fault detector (210) is connected.

[0108] In other words, when the first fault detector (210-1) is connected between the first power line (410) and the ground, and the second fault detector (210-2) is connected between the second power line (420) and the ground, in the case of a decrease in ground potential, the first safety voltage maintenance switch (310) corresponding to the first fault detector (210-1) is installed between the first power line (410) and the ground, and the second safety voltage maintenance switch (320) corresponding to the second fault detector (210-2) is installed between the second power line (420) and the ground, and in the case of detection of leakage current, the first safety voltage maintenance switch (310) corresponding to the first fault detector (210-1) is installed between the second power line (420) and the ground, and the second safety voltage maintenance switch (320) corresponding to the second fault detector (210-2) is installed between the first It can be installed between the power line (410) and the ground.

[0109] FIG. 8 is a conceptual diagram for explaining the operation when a leakage current or ground fault occurs in one phase in another embodiment of the present invention illustrated in FIG. 7.

[0110] According to FIG. 8, when the fault detector (210-1, 2) detects that the ground potential has decreased below a set value and operates, if a leakage current or ground fault occurs in the first power line (410) among the two power lines (410, 420) and leakage current 1 flows, the ground voltage (potential) detected by the first fault detector (210-1) connected between the first power line (410) and the ground decreases to a set reference value or more, and therefore the second safety voltage maintenance switch (320) is controlled by the first fault detector (210-2) in which the leakage current 1 has occurred to ground the first power line (410) to the ground through the safety voltage maintenance element (321).

[0111] In addition, when the fault detector (210-1, 2) detects leakage current and operates, if a leakage current or ground fault occurs in the first power line (410) among the two power lines (410, 420) and leakage current 1 flows, the leakage current 1 flows through the second fault detector (210-2) connected between the second power line (420) and the ground at a level exceeding a predetermined reference value, and therefore the second safety voltage maintenance switch (320) is controlled by the second fault detector (210-2) that detected the leakage current 1 to ground the first power line (410) to the ground through the safety voltage maintenance element (321).

[0112] In this way, when the first power line (410) in which a leakage current or ground fault has occurred is grounded to the ground through the safety voltage maintenance element (321) by the second safety voltage maintenance switch (320), the ground potential of the first power line (410) is maintained below the safety voltage by the safety voltage maintenance element (321), so that the leakage current 1 flowing from the first power line (410) to the ground is reduced by the ground potential maintained below the safety voltage, and electrical accidents such as electric shock or fire are fundamentally prevented.

[0113] On the contrary, if a leakage current or ground fault occurs in the second power line (420) among the two power lines (410, 420) and leakage current 2 flows, the leakage current 2 flows through the first fault detector (210-1) connected between the first power line (410) and the ground at a level exceeding a predetermined reference value, and thus the first safety voltage maintenance switch (310) is controlled by the first fault detector (210-1) that detects the leakage current 2 to ground the second power line (420) to the ground through the safety voltage maintenance element (311).

[0114] In this way, when the second power line (420) in which a leakage current or ground fault has occurred is grounded to the ground through the safety voltage maintenance element (311) by the first safety voltage maintenance switch (310), the ground potential of the second power line (420) is maintained below the safety voltage by the safety voltage maintenance element (311), so that the leakage current 2 flowing from the second power line (420) to the ground is reduced by the ground potential of the second power line (420) being maintained below the safety voltage, and electrical accidents such as electric shock or fire are fundamentally prevented.

[0115] In the above, one embodiment and another embodiment of the present invention have been described using a case where the power supply unit (100) is a single-phase AC power supply as an example, but the technical idea of ​​the present invention is not limited thereto and can be applied to a DC circuit as well as a multi-phase AC circuit including a three-phase circuit.

[0116] As an example, the following describes the configuration of one embodiment and another embodiment of the present invention applied to a three-phase AC circuit.

[0117] Figure 9 is a wiring diagram when a configuration according to one embodiment of the present invention is applied to a three-phase AC power supply.

[0118] Referring to FIG. 9, a system for maintaining a ground potential safety voltage in case of direct or indirect contact (ground fault, leakage current) according to an embodiment of the present invention includes a power supply unit (100) that is a three-phase AC power source including an R phase, an S phase, and a T phase, a fault detector (210) that includes first to third fault detectors (210-1, 210-2, 210-3) that are respectively connected between the R phase, the S phase, and the T phase and the ground, and a safety voltage maintenance switching unit (300) that includes first to third safety voltage maintenance switches (310, 320, 330) corresponding to the first to third fault detectors (210-1, 210-2, 210-3), respectively, wherein the first to third safety voltage maintenance switches (310, 320, 330) operate when an operating current of a predetermined reference value or more flows to the corresponding fault detector (210) to open the contact. It is characterized by being a normally closed (NC) type switch.

[0119] At this time, the first to third safety voltage maintenance switches (310, 320, 330) may be installed between the other end of the safety voltage maintenance element (311, 321, 331) connected to the plurality of power lines (410, 420, 430) and the ground so that when a person comes into contact with, or a current leakage or ground fault occurs in, one or more of the first to third power lines (410, 420, 430) connected to the R phase, S phase, and T phase, the corresponding power line is grounded to the ground through the safety voltage maintenance element (311, 321, 331). More specifically, the first to third safety voltage maintenance switches (310, 320, 330) and the safety voltage maintenance element (311, 321, 331) may be connected in series and connected in parallel to each corresponding fault detector (210).

[0120] In a three-phase AC circuit having a configuration according to one embodiment of the present invention, when a person comes into contact with one of the first to third power lines (410, 420, 430) or a current leakage or ground fault occurs, the ground voltage at both ends of the fault detector (210) connected between the power line and the ground drops, so that the current flowing to the fault detector (210) or the ground potential becomes lower than a predetermined reference value, and thus the safety voltage maintenance switch controlled by the fault detector (210) is short-circuited.

[0121] In this way, when a power line (410, 420, 430) that a person has come into contact with or where a current leakage or ground fault has occurred is grounded to the ground by a safety voltage maintenance switch (310, 320, 330) and a safety voltage maintenance element (311, 321, 331), the leakage current flowing from the power line (410, 420, 430) to the ground is maintained below the safety voltage by the short-circuited safety voltage maintenance switch (310, 320, 330) and the safety voltage maintenance element (311, 321, 331) instead of to a human body, surrounding equipment, or flammable objects, thereby fundamentally preventing electrical accidents such as electric shock or fire, and by removing the ground of the system circuit of the present invention, the leakage current can be made zero. At this time, the ground release switch (350) can be operated.

[0122] In addition, when a leakage current or ground fault occurs simultaneously in multiple power lines among the first to third power lines (410, 420, 430), the current flowing in the fault detector (210) connected to the power line (410, 420, 430) where the leakage current or ground fault occurred all falls below a predetermined reference value, so that the safety voltage maintenance switches controlled by the corresponding fault detector (210) are short-circuited, and the power line (410, 420, 430) where the leakage current or ground fault occurred can be controlled to be grounded to the ground through the safety voltage maintenance element (311, 321, 331). In addition, when a fault detector (210) detects that a current leakage or ground fault has occurred in multiple power lines (410, 420, 430), the circuit breaker (500) installed between the load unit (900) and the first to third power lines (410, 420, 430) can be opened to control the power supply from the power supply unit (100) to the load unit (900) through the power lines (410, 420, 430).

[0123] In order to prevent the power lines (410, 420, 430) from being momentarily short-circuited by each other due to the operation of the multiple safety voltage maintenance switches before the circuit breaker (500) cuts off the power supply when a current leakage or ground fault occurs in multiple power lines (410, 420, 430), safety voltage maintenance elements (311, 321, 331) are installed in series with the safety voltage maintenance switches, but a short-circuit prevention element may also be installed, and the short-circuit prevention element may be an inductor element for limiting the momentary short-circuit current.

[0124] As seen, in a structure such as an embodiment of the present invention, the safety voltage maintenance switch is configured as a normally closed (NC) type, so that it is possible to detect a situation in which a ground fault or current leakage occurs not only in one line of a power line (410, 420, 430) but also in a plurality of power lines (410, 420, 430), and in a situation in which a ground fault or current leakage is detected in a plurality of power lines (410, 420, 430), the circuit breaker (500) can be opened and closed to electrically isolate the power supply unit (100) from the power lines (410, 420, 430).

[0125] In addition, it is possible to check whether the circuit of the system of the present invention operates normally by using the test switches (710, 720, 730) and test elements (810, 820, 830) described in the detailed description of FIG. 1 through the operation of the test switches (710, 720, 730). A detailed description of this is omitted because it has been described in the detailed description of FIG. 1.

[0126] Figure 10 is a wiring diagram when a configuration according to another embodiment of the present invention is applied to a three-phase power supply.

[0127] Referring to FIG. 10, a system for maintaining a ground potential safety voltage in case of direct or indirect contact (ground fault, leakage current) according to another embodiment of the present invention, the power supply unit (100) is a three-phase AC power source including an R phase, an S phase, and a T phase, the fault detector (210) includes first to third fault detectors (210-1, 210-2, 210-3) connected between the R phase, the S phase, and the T phase and the ground, respectively, and the safety voltage maintenance switching unit (300) includes first to third safety voltage maintenance switches (310, 320, 330) corresponding to the first to third fault detectors (210-1, 210-2, 210-3), respectively, wherein the first to third safety voltage maintenance switches (310, 320, 330) are turned on when an operating current equal to or greater than a predetermined reference value flows to the corresponding fault detector (210). It is characterized by being a normally open (NO) type switch with short circuit contacts.

[0128] At this time, the first to third safety voltage maintenance switches (310, 320, 330) may be installed between the other end of the safety voltage maintenance element (311, 321, 331) connected to the plurality of power lines (410, 420, 430) and the ground so that when a person comes into contact with, or a current leakage or ground fault occurs in one or more of the first to third power lines (410, 420, 430) connected to the R phase, S phase, and T phase, the corresponding power line (410, 420, 430) is grounded to the ground through the safety voltage maintenance element (311, 321, 331), and also, when a current leakage or ground fault occurs in the neutral line (440) connected to the neutral point (N) of the R phase, S phase, and T phase, the neutral line (440) is grounded to the ground. It is also possible to install it between the neutral line (440) and the ground.

[0129] Each of the first to third fault detectors (210-1, 210-2, 210-3) may be configured to include a current detection unit (211) for detecting leakage current, as illustrated in FIG. 2(b), a unidirectional current unit (212) for limiting the path of leakage current so that the leakage current flows in one direction through the current detection unit (211), and a leakage current limiting element (213).

[0130] In particular, as illustrated in FIG. 10, if the current conduction direction of the unidirectional current section (212) of each of the first to third fault detectors (210-1, 210-2, 210-3) is configured to be in the direction of flowing out or inflowing from the ground, then in a normal state where no person is in contact or no leakage or ground fault occurs, no leakage current flows to the fault detector (210), and only when a leakage current occurs in one of the first to third power lines (410, 420, 430), the fault detector (210) detects the leakage current and operates the corresponding safety voltage maintenance switch.

[0131] The safety voltage maintenance switch is a normally open (NO) type switch whose contacts are short-circuited by a detection signal output when a decrease in ground potential exceeding a predetermined reference value is detected by a corresponding fault detector (210) or when a leakage operating current flows. When a decrease in ground potential is detected, the corresponding fault detector (210) is electrically connected to the power line (410, 420, 430) to which the fault detector (210) itself, to which the ground potential is reduced, is connected, and when a leakage current is detected, the corresponding fault detector (210) is electrically connected to a power line (410, 420, 430) other than the power line (410, 420, 430) to which it is connected.

[0132] In other words, when a leakage current or ground fault occurs in any one of the first to third power lines (410, 420, 430) and the ground potential decreases, a decrease in the ground potential greater than a predetermined standard is detected by the fault detector (210) connected to the power line (410, 420, 430) in which the leakage current or ground fault occurred among the first to third fault detectors (210-1, 210-2, 210-3), so that the safety voltage maintenance switch linked to the detection signal of the fault detector (210) can be arranged so that the power line (410, 420, 430) in which the leakage current or ground fault occurred can be grounded to the ground through the safety voltage maintenance element (311, 321, 331).

[0133] In addition, when a leakage current flows due to a current leak or ground fault in any one of the first to third power lines (410, 420, 430), an operating current higher than a predetermined reference value flows in the remaining fault detectors (210) except for the fault detector (210) connected to the power line (410, 420, 430) where the current leak or ground fault occurred among the first to third fault detectors (210-1, 210-2, 210-3), so that a safety voltage maintenance switch linked to the detection signal of the remaining fault detectors (210) can be arranged so that the power line (410, 420, 430) that is touched by a person or has a current leak or a ground fault can be grounded to the ground through the safety voltage maintenance element.

[0134] For example, referring to FIG. 10, assuming that the first to third fault detectors (210-1, 210-2, 210-3) are connected between the first to third power lines (410, 420, 430) and the ground, respectively, the second and third safety voltage maintenance switches (320, 330) corresponding to the second and third fault detectors (210-2, 210-3) are connected in series between the first power line (410) and the ground, the first and third safety voltage maintenance switches (310, 330) corresponding to the first and third fault detectors (210-1, 210-3) are connected in series between the second power line (420) and the ground, and the first and second fault detectors (210-1, 210-2) are connected in series between the third power line (430) and the ground. The first and second safety voltage maintenance switches (310, 320) may be configured to be connected in series with a safety voltage maintenance element.

[0135] In addition, if the neutral point (N) or neutral line (440) is missing or grounded, leakage current flows to all of the first to third fault detectors (210-1, 210-2, 210-3), so the first to third safety voltage maintenance switches (310, 320, 330) can be connected in series with the safety voltage maintenance element between the neutral line (440) and the ground.

[0136] However, the wiring configuration of FIG. 10 is merely an example according to another embodiment of the present invention, and various methods and configurations may be devised, such as logically calculating the detection result of the fault detector (210) to ground the power line (410, 420, 430) or neutral line (440) where a leakage or ground fault has occurred.

[0137] According to another embodiment of the present invention, when a leakage current or ground fault occurs in a power line (410, 420, 430) or a neutral line (440) in a three-phase AC circuit, the power line (410, 420, 430) or the neutral line (440) can be grounded to the ground, so that the leakage current flowing from the power line (410, 420, 430) or the neutral line (440) to the ground flows to the ground through the safety voltage maintenance switch instead of to a human body, surrounding equipment, or flammable objects, thereby fundamentally preventing the occurrence of electrical accidents such as electric shock or fire.

[0138] In addition, the power distribution system according to the present invention may further include a surge protector (not shown in the drawing) electrically connected between two or more power lines (410, 420, 430) and at least one neutral point (N) having a potential between the voltages of the two or more power lines (410, 420, 430) and the ground. At this time, by configuring the device to detect leakage current due to a defect, deterioration, or failure of the surge protector, the defect, deterioration, or failure of the surge protector can be recognized.

[0139] A surge protector is a component that protects surrounding equipment by suppressing abnormal surge voltages that are introduced into power lines (410, 420, 430) and neutral lines (440) due to lightning, etc., and a varistor is a representative example.

[0140] Due to the deterioration or failure of the surge protector and the inflow of overvoltage exceeding the rated capacity, the elements of the surge protector may be degraded, causing leakage current to flow similar to an electric leakage or ground fault even in normal conditions. In this case, the electric shock prevention device according to the present invention detects leakage current due to the defect, deterioration, or failure of the surge protector, thereby recognizing that a defect, deterioration, or failure has occurred in the surge protector and notifying the manager so that the manager can replace the surge protector in a timely manner.

[0141] Through the above-described configuration, the electric shock prevention device according to the present invention and the power distribution system equipped therewith detect a leakage current between a power line transmitting AC or DC electricity and the ground, and when a leakage current occurs, ground the power line or neutral line (440) through which the leakage current flows to the ground, thereby preventing the leakage current from flowing to the human body and causing an electric shock.

[0142] In addition, it has the effect of preventing the occurrence of fire caused by ground fault or leakage current by detecting leakage current caused by ground fault or leakage current occurring in one or more lines and fundamentally preventing leakage current from flowing to the outside.

[0143] While the present invention has been described and illustrated based on preferred embodiments to illustrate the principles of the present invention, the present invention is not limited to the configuration and operation as illustrated and described. It should be understood that the embodiments described above are exemplary in all respects and not restrictive. The scope of the present invention is defined by the following claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

[0144]

[0145] [Explanation of symbols]

[0146] 100: Power supply

[0147] 210, 210-1, 210-2, 210-3: Fault detectors

[0148] 211: Current detection unit or voltage detection unit 212: Unidirectional current unit

[0149] 213: First to third leakage current limiting elements

[0150] 300: Safety voltage maintenance switching unit

[0151] 310, 320, 330: 1st to 3rd safety voltage maintenance switches

[0152] 311, 321, 331: Elements for maintaining the first to third safety voltages

[0153] 350: Ground release switch

[0154] 410, 420, 430: Power lines 1 to 3

[0155] 440: Neutral wire 500: Load side circuit breaker 501: Power side circuit breaker

[0156] 610, 620, 630: Fault alarms for power lines 1 to 3

[0157] 710, 720, 730: Test switch of power lines 1 to 3 (insulation resistance fluctuation, ground potential fluctuation, or leakage current generation)

[0158] 810, 820, 830: Test components (resistors, capacitors, etc.) for the first to third power lines

[0159] Multiple test elements (811, 812, 813, 814, 815, etc.) connected to the first power line

[0160] Multiple test elements (821, 822, 823, 824, 825, etc.) connected to the second power line

[0161] Multiple test elements (831, 832, 833, 834, 835, etc.) connected to the third power line

[0162] 900: Subordinate Department

[0163] N: neutral point

Claims

1. One or more fault detectors electrically connected to the power supply to transmit alternating current or direct current from the power supply to the load equipment, configured between the power line of the TN grounded distribution system or the IT grounded distribution system, and the neutral point and the ground having a potential between the voltages of the two or more power lines, constantly monitor the quality of electricity, and a test switch connected at least one end to the power line has the other end connected in series to one end of one or more test elements so that the other end of the test elements is grounded, and by operating the test switch, a test for variation of insulation resistance or leakage current or ground potential is performed, and an inspection for a reference set value is performed through the fault detector, or A fault detector configured to detect a decrease in insulation resistance or a leakage current size or a decrease in ground potential between at least one neutral point having a potential between the voltages of the two or more power lines electrically connected to the power supply unit and the ground, wherein the fault detector grounds a safety voltage maintenance switch connected to the corresponding power line or neutral point to the ground through a safety voltage maintenance element so that the ground potential becomes lower than the safety voltage when the decrease in insulation resistance or the increase in leakage current or the decrease in ground potential among the two or more power lines and the neutral point occurs by a predetermined set value or more, or A system for maintaining ground potential safety voltage in case of direct or indirect contact (ground fault, leakage current), characterized in that when the fault detector detects a decrease in insulation resistance or a decrease in ground potential or a leakage current between the power line and the ground and detects a value exceeding a predetermined set value, the system operates a ground release switch to disconnect all circuits electrically connected between the power line and the ground, thereby preventing and eliminating the occurrence of the ground potential and the leakage current, and the system detects a fault state of the power line and notifies it wired or wirelessly.

2. In paragraph 1, The above fault detector is characterized in that it is electrically connected between at least one of the two or more power lines and the neutral point and the ground to detect the power quality and insulation status of at least one of the power lines, the neutral line, the neutral point, and the ground, and performs at least one of alarm, notification, monitoring, control, blocking, and restoration, wired or wirelessly. A system for maintaining a safe voltage to ground potential in the event of direct or indirect contact (ground fault, leakage current).

3. In paragraph 2, A system for maintaining ground potential safety voltage in the event of direct or indirect contact (ground fault, leakage current), characterized by further including a safety voltage maintenance switching unit controlled to ground by short-circuiting a power line or neutral point, in which a decrease in insulation resistance, a decrease in ground potential, or a leakage current has occurred, to the ground through a safety voltage maintenance element, according to the detection result of the fault detector.

4. In paragraph 3, The above fault detector includes two or more fault detectors each electrically connected between the two or more power lines and the ground, A ground potential safety voltage maintenance system in case of direct or indirect contact (ground fault, leakage current), characterized in that the above-mentioned safety voltage maintenance switching unit includes two or more safety voltage maintenance switches whose turn-on or turn-off is controlled in response to each of two or more fault detectors.

5. In paragraph 4, A system for maintaining a ground potential safety voltage in the event of direct or indirect contact (ground fault, leakage current), characterized in that at least one of the two or more safety voltage maintenance switches is a normally open (NO) type switch that turns on when an operating current exceeding a predetermined reference value flows to a corresponding fault detector, and is electrically connected to at least one of the power lines and neutral points other than the power line to which the corresponding fault detector is connected among the two or more power lines and neutral points.

6. In paragraph 4, At least one of the two or more safety voltage maintenance switches is a normally open (NO) type switch that is turned on when the insulation resistance of the corresponding fault detector decreases by a predetermined standard value or the ground potential decreases, A system for maintaining a safe voltage to ground potential in the event of direct or indirect contact (ground fault, leakage current), characterized in that it is electrically connected to at least one of the safety voltage maintaining elements connected to the power line and neutral point, among the two or more power lines and neutral points, in which the insulation resistance is reduced or the ground potential is reduced.

7. In the fourth paragraph A ground potential safety voltage maintenance system in case of direct or indirect contact (ground fault, leakage current), characterized in that at least one of the two or more safety voltage maintenance switches is a normally closed (NC) type switch that is turned off when an operating current exceeding a predetermined reference value flows to a corresponding fault detector, and is electrically connected in series with a safety voltage maintenance element to the corresponding fault detector and connected in parallel with the safety voltage maintenance element.

8. In paragraph 1, The above fault detector is characterized by including a current detection unit that limits the leakage current to a predetermined dangerous current or lower, or a voltage detection unit that detects the leakage current while maintaining the ground voltage of the faulty power line at a safe voltage, or a ground potential maintenance system for ground potential in the event of direct or indirect contact (ground fault, leakage current).

9. In paragraph 5, The above fault detector, A current detection unit that limits the leakage current to a predetermined dangerous current or less and detects the leakage current; and A system for maintaining a ground potential safety voltage in the event of direct or indirect contact (ground fault, leakage current), characterized by including a unidirectional current section that limits the path of the leakage current so that the leakage current flows in one direction through the current detection section.

10. In paragraph 1, It further includes a circuit breaker configured to open and close the electrical connection between the power line and the load. A system for maintaining a ground potential safety voltage in case of direct or indirect contact (ground fault, leakage current), characterized in that the fault detector controls the circuit breaker to cut off the electrical connection between the load and the power line when a leakage current occurs in two or more of the power lines.

11. In paragraph 10, The above load is a three-phase AC power source including an R phase, an S phase, and a T phase, and the fault detector is The first to third fault detectors are respectively connected between the R phase, S phase and T phase and the ground, and the safety voltage maintenance switching unit is Including first to third safety voltage maintenance switches corresponding to each of the first to third fault detectors and turned on when an operating current exceeding a predetermined reference value flows to the corresponding fault detector or when the ground potential decreases, The first to third safety voltage maintenance switches are installed between the plurality of power lines and the ground so as to be grounded to the ground through a safety voltage maintenance element in order to maintain the safety voltage of the ground potential of the power line when a leakage or ground fault occurs in any one of the plurality of power lines connected to the R phase, S phase, and T phase. A system for maintaining the ground potential safety voltage in case of direct or indirect contact (ground fault, leakage).

12. In paragraph 10, The above load is a three-phase AC power source including an R phase, an S phase, and a T phase, and the fault detector is The first to third fault detectors are respectively connected between the R phase, S phase and T phase and the ground, and the safety voltage maintenance switching unit is Including first to third safety voltage maintenance switches corresponding to each of the first to third fault detectors and turned off when an operating current exceeding a predetermined reference value flows to the corresponding fault detector, The first to third safety voltage maintenance switches are installed between the other end of a safety voltage maintenance element connected to one end of the plurality of power lines and the ground so that when a leakage or ground fault occurs in one or more of the plurality of power lines connected to the R phase, S phase, and T phase, the power line is grounded to the ground through the safety voltage maintenance element. This is a ground potential safety voltage maintenance system in case of direct or indirect contact (ground fault, leakage).

13. In paragraph 1, The above test switch is a ground potential safety voltage maintenance system in case of direct or indirect contact (ground fault, leakage current), characterized in that the part connected to the two or more power lines and the ground is configured with any one of a plug, a clamp, a terminal, and a clip, and is installed as a selector switch or cam switch capable of electrically selecting any one of the two or more connected power lines.

14. In paragraph 1, A system for maintaining a ground potential safety voltage in the event of direct or indirect contact (ground fault, leakage current), characterized in that the test element is composed of at least one of a resistor, a capacitor, an inductor, and a diode, and is connected to the test switch by an electrically selectable selector switch or cam switch among the test elements.

15. In paragraph 1, Further comprising a surge protector electrically connected between the two or more power lines and at least one neutral point having a potential between the voltages of the two or more power lines and the ground, A system for maintaining a safe voltage to ground potential in case of direct or indirect contact (ground fault, leakage current), characterized by detecting a defect, deterioration or insulation failure of the above surge protector.

16. Step of supplying power to the power line and load; A step of setting a predetermined setting value for ground potential, leakage current or insulation resistance in a fault detector; A step in which the above fault detector detects the electrical quality of the power supply and monitors it wired or wirelessly; A fault detector that compares the detected power quality and the reference set value with a predetermined reference set value and determines that, in the event of a decrease in insulation resistance, a change in ground potential, or occurrence of leakage current, operates a safety voltage maintenance switch connected to the corresponding power line or neutral point (N) to ground the fault line to the ground through a safety voltage maintenance element; A control method for a ground potential safety voltage maintenance system in case of direct or indirect contact (ground fault, leakage current), characterized by including a step of operating a circuit breaker to cut off power supplied to a load and notifying it wired or wirelessly when the result values ​​detected by a fault detector (210) are two or more places.

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