KR20170042070A - Apparatus and method for preventing disaster caused by short-circuit in electric power systems - Google Patents

Abstract

Disclosed are an apparatus and a method to prevent a disaster when a short circuit occurs in a power system, using fail power short-circuited when a short circuit occurs on a load side of a power distribution line installed in a power system to decrease a short circuit current of a supply power side and decrease an output voltage of the load side, so as to prevent an electric accident due to the short circuit current. According to the present invention, the apparatus comprises: a warning generator to interlink with the power system (power distribution line) for supplying power to a single or three-phase, and to warn occurrence of a short circuit; a warning release signal input unit to release a warning; and a short circuit correction device. The short circuit correction device comprises: a short circuit power converter to generate a short circuit signal simultaneously with the occurrence of the short circuit when the short circuit occurs, to prevent a casualty accident due to an electric shock, reduce the output value of the load side while changing an electric connection position of a coil connected to a power input terminal, distribute the voltage inputted to the power input terminal to the coil of which the position is changed to reduce the short circuit current when earth fault occurs due to a short circuit as a ground potential difference of the short-circuited power is reduced more than a potential difference of the power, and to allow a harmonic wave to flow once in normal and inverse phases which are converted by 180 angular degrees when the harmonic wave is generated on the load side; a switch to transfer the short circuit signal; and a switch to output power cut-off and warning signals in accordance with an electric signal outputted from the switch.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an apparatus and a method for preventing disasters in a power system,

The present invention relates to an apparatus and a method for preventing a disaster when a short circuit occurs in a power system. More specifically, the present invention eliminates harmonics in a power system of a single phase RN, SN, TN) or a three phase R, S, T power system. When a short circuit occurs, To prevent an accident from occurring, and to prevent a secondary electric current from being generated due to a power failure due to an overcurrent due to a short circuit and to a short-circuited portion, and to prevent a disaster from occurring in a power system when a short circuit occurs .

In the information society, electricity is like an artery, and managing it is an important starting point for improving the quality of life.

Generally, in the power system, the 22.9 kv-y power distribution system supplies power directly from a substation to a large-scale customer such as a factory or a building through a 3-phase 4-wire distribution line, or through a secondary transformer to a small- To the power supply.

Such distribution lines are constructed in the form of machined lines in the outskirts of cities and farming and fishing villages, but they are buried underground in areas where beauty is important, such as large cities and amusement parks.

The three-phase four-wire distribution system combines the neutral (N) and power lines (A-phase, B-phase, C-phase) by means of Y connection, delta connection and wieder connection. Here, when one power line and another power line are connected at the power connection, the voltage becomes 380V. When one power line (for example, A phase) and the neutral line (N) are connected, 220V is supplied to the load.

The characteristics of the distribution system of Korea which adopts 3 phase 4 wire system is that single phase load and 3 phase load are mixed and unbalanced current flows in the neutral line. Recently, computer, LED, lighting equipment, office equipment such as copying machine, uninterruptible power supply (UPS) due to the increase of nonlinear load devices, more neutral image lines were flowing more harmonics.

Harmonics is a frequency corresponding to an integer multiple of 2, 3, or 4 times the fundamental frequency, and is referred to as a distortion or a distorted wave. In particular, harmonics such as 3, 6, 9, The high frequency component corresponding to a multiple of 3 is referred to as image harmonic.

As image phase harmonics have the same phase of each of the three phases, three single phase power sources are connected in parallel, so that the image harmonics up to 3 times are superimposed on the neutral line. When excessive image harmonics flow in the neutral line, the bushing portion is disconnected due to overheating of the neutral conductor, or the neutral line is overheated, resulting in a short circuit in the converter.

If a short circuit occurs, unbalanced power is generated in the load side as well as damage to persons and property due to sparks, overheating, etc., and the load of the refrigerator and the washing machine connected to the three-phase line is burned.

This will be described in more detail as follows.

And is managed through various relay apparatuses in a step-by-step manner for the stable use of electricity from electric faults such as short circuits. Electric utilities transmit ultrahigh pressure for energy efficiency, and as it goes down to the lower car consumer, they are converted to lower voltage step by step through the transformer. The relay detects the input voltage and current to detect the overcurrent / overvoltage / phase / reverse / ground fault current and operates the circuit breaker (CB) So that the fault of the car customer can be prevented from propagating to the electric appliance side or the fault of the electric appliance side can be prevented from propagating to the car customer side so that the entire system network can be stably operated.

The most typical operations during these relay operations are overcurrent and ground fault. In general, the overcurrent is present in the load, and therefore, the customer-side relay must detect the abnormal current on the load side and shut off the load. Therefore, the relay operation by the most common overcurrent occurs by individual operation, and only the upper relay in which the overcurrent occurs can be operated. If the generated overcurrent was a large current that could operate up to the top relay (electric carrier relay), the upper relay would also block the upper breaker by overcurrent operation, which would cause a major accident to shut down all the car users connected to the electric carrier at the same time . Therefore, in order to suppress such an operation, the overcurrent relay has various operating conditions such as a predetermined time / inverse time / early time, and the operation time is variablely operated according to the magnitude of the overcurrent. In other words, the operation time of the lower overcurrent relay is set to be faster than the operation time of the upper overcurrent relay, so that the overcurrent generating load can be separated from the system in a short period of time, so that the entire system can be stably operated.

 However, in the case of the electric use condition of the general consumer, if a short-circuit current occurs, the breaker does not operate according to the length or thickness of the load-side wire using the breaker capacity and electricity, Even if it is operated, instantaneous sparks and electrical accidents caused by overcurrents cause many lives and property damage every year.

 In addition, even when the overcurrent relay is operated, the main breaker and the load side breaker are simultaneously shut off, and the transformer fuse of KEPCO is also blocked, so that a large number of customers suffer secondary damage due to power outage, Damage to property of user and national development of Korea are being hindered.

 In order to solve all the problems caused by this short circuit, a conventionally proposed technique is disclosed in Korean Patent Registration No. 10-0422759 (registered on Mar. 02, 2004) (name of invention: power supply device, (Hereinafter referred to as " prior art 1 "), Korean Patent Application Publication No. 20-2012-0008678 (entitled "Quot;).

The disclosed 'Prior Art 1' is a power supply device for converting a first DC voltage to a second DC voltage and outputting the second DC voltage, comprising: a reference voltage generating circuit for generating a reference voltage; A control circuit for controlling an output voltage at an output side in accordance with the reference voltage; And a short-circuit detection circuit for detecting an occurrence of a short-circuit when a short-circuit occurs on the output side to reduce the reference voltage to reduce the output voltage, thereby performing an output short-circuit protection operation, And a diode connected between the reference voltage generating circuit.

The disclosed 'Prior Art 2' includes a housing including an enclosure and a cover covering the enclosure; A plurality of unipolar blocking units accommodated in the housing and formed by coupling the left case and the right case; And a flare preventing means for preventing flare of the left case and the right case, wherein the flare preventing means comprises: a locking protrusion protruding from any one of the monopolar blocking unit or the housing; And a latching portion formed in the other one of the latching protrusions.

Patent Registration No. 10-0422759 (registered March 2, 2004) Published patent 20-2012-0008678 (Dec. 18, 2012)

In the conventional technology 1, the reference voltage is a commercial power supply and the output voltage is a commercial power supply. In a commercial power supply, a short circuit occurs and a spark occurs at the same time. In the conventional technology 1, There is a disadvantage that it can not prevent a short circuit accident of the commercial power supply. In addition, 'Prior Art 2' is a structure for preventing arc from being invaded by other circuits so as to increase the safety of the circuit breaker. Generally, the circuit breaker performs a function of preventing a short circuit accident, In case that the terminal of the circuit breaker is melted and welded due to the overcurrent during the short circuit and the accident is spread and the terminal of the circuit breaker is melted and exploded and the accident spreads to the outside, the short circuit is judged as normal overload, There is a disadvantage in that it can not perfectly cope with a short circuit accident such as an operation failure of the breaker.

Disclosure of Invention Technical Problem [8] The present invention has been proposed in order to solve the above-mentioned problems occurring in the conventional single phase and three phase power systems,

A problem to be solved by the present invention is to provide a power system in which short-circuit (short-circuit) is generated in a power system for preventing an electric fire from occurring due to a spark, an over-current, And an apparatus and method for preventing a disaster at the time of occurrence.

Another problem to be solved by the present invention is to provide an apparatus and method for preventing a disaster at the time of occurrence of a short circuit in a power system which can quickly and accurately catch the occurrence of a short circuit current and prevent damage caused by a short circuit will be.

Another object to be solved by the present invention is to provide an apparatus and method for preventing a disaster when a short circuit occurs in a power system in which only a short-circuited load side is cut off or a warning is issued and an administrator's follow- .

Another problem to be solved by the present invention is to reduce the power supply side short circuit current so that the main breaker of the power supply side is operated by occurrence of a short circuit or the fuse of the KEPCO transformer is disconnected, And an apparatus and method for preventing a disaster when a short circuit occurs in the system.

Another object to be solved by the present invention is to provide a disaster prevention apparatus (hereinafter, referred to as " disconnection prevention apparatus ") in a power system for preventing a short circuit from occurring when an electric shock occurs, And a method thereof.

Another problem to be solved by the present invention is to prevent the occurrence of electric accidents due to unbalanced power due to harmonics by eliminating harmonics generated in a nonlinear load and to prevent the occurrence of a short circuit in a power system Disaster prevention apparatus and method.

According to the present invention, there is provided an apparatus for preventing a disaster at the time of occurrence of a short circuit in a power system, comprising: And a short-circuit correcting device for reducing a short-circuit current and reducing a load-side output voltage, thereby preventing an electric accident caused by a short-circuit current.

In case of short-circuit from power system to power distribution line, the fault power of the short-circuited load is reduced to reduce the potential difference and output voltage with the ground to reduce the risk of spark, overcurrent, overheating and electric shock, And a fault correcting device for preventing the power source side power source from being cut off.

And the short-circuit correction device includes a short-circuit power converter that generates a short-circuit electric signal upon occurrence of a short circuit when the short-circuit occurs.

The short-circuit power converter includes a coil (inductance) for canceling harmonics generated by causing the harmonics to flow once in a phase opposite to the normal phase in which the phase of the power is converted by 180 degrees when a harmonic is generated in the load side.

The short-circuit power converter is characterized in that, when a short circuit occurs on the load side, the ground potential difference of short-circuited electric power is lower than the electric potential difference of the power source to prevent human accidents due to electric shock when a short circuit (short circuit) occurs.

The short-circuit power converter changes the electrical connection position of the coil connected to the power input terminal when the short circuit occurs, and distributes the voltage input to the power input terminal to the coil whose position is changed to reduce the short- And the output voltage is reduced.

The short-circuit disaster prevention device includes an alarm generator for informing occurrence of a short circuit according to an electrical signal output by the switch; And an alarm release signal input unit for generating an alarm release electric signal and transmitting the alarm release electric signal to the short circuit correction device when the alarm release switch for alarm release is operated by the manager after the alarm is generated by the alarm generator.

In order to solve the above problems, a "disaster prevention method in a short-circuit in a power system" according to the present invention is a method of preventing a short-circuit (short-circuit) accident when a short circuit occurs on the output side of a distribution line equipped with a fault- Wherein when the input power is supplied to the short circuit correcting device through the power line of the power system, the short circuit correcting device supplies the normal power to the load side; If the resistance value of the load line decreases due to the occurrence of a short circuit on the load side, the electrical connection position of the coil (inductance), which is a coil connected to the power input terminal to which the input power is supplied, ; A step in which a switch is operated by transmitting a voltage generated at a power output terminal in a short circuit to a switch provided in the short circuit correcting device due to a change in the electrical connection position of the coil (inductance); A switch provided in the short circuit correcting device operates to stop supplying output power or operate an alarm generator; When the alarm generator operates, an alarm release request electric signal is transmitted by an administrator and the alarm is released by an alarm release request electric signal.

According to the present invention, when a short circuit occurs in a power system, overheating of a spark, an overcurrent, and a wire caused by a short-circuit current is prevented and a short circuit is generated by short- It is possible to prevent the occurrence of a large power outage in which electric accidents caused by short-circuiting of a part of the load are spread.

Further, according to the present invention, even if a breaker having a short-circuit current capacity of a small amount is short-circuited, the short-circuited load side can be controlled and blocked in real time and alarmed, So that it is possible to prevent a person, property, and power distribution apparatus from being burned out, which may occur due to the occurrence of a short circuit, in advance.

According to the present invention, it is possible to increase the efficiency of power by canceling harmonics generated in a non-linear load, prevent electric accidents due to overcurrent, overvoltage, and short circuit caused by a neutral wire failure, There is an advantage.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of a disaster prevention apparatus in a short-circuited state in a power system according to a preferred embodiment of the present invention; FIG.
2 is a circuit diagram of a disaster prevention apparatus in a short-circuited state in a power system according to a preferred embodiment of the present invention.
3 is a circuit diagram of a short-circuit power converter and a vector diagram of normal power and short-circuit power.
4 is a waveform diagram of each coil of the short-circuit power converter with respect to harmonic cancellation;
5 is a flow chart illustrating a disaster prevention method at the time of a short circuit in a power system according to a preferred embodiment of the present invention.

Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

FIG. 1 is a block diagram of a disaster prevention apparatus 200 in a power system according to a preferred embodiment of the present invention. In the short-circuit state of a load 300 connected to a power distribution line 100 of a power system, Protects the power supply (distribution line) from short circuit current.

When the disaster prevention device 200 is implemented as a single module and commercialized, it can be easily applied to existing installed electric devices.

Power system (distribution line) (100) means a general distribution line that supplies electric power supplied by KEPCO to each load of the customer.

The disaster prevention device 200 in the short circuit is connected to the distribution line 100 supplying electric power through the single phase (RN, SN, TN) or the three-phase four-wire type (R, S, T, N) 100 short-circuited at the load 300 side, the short-circuit current is reduced to prevent the occurrence of personal injury and property damage due to a short circuit.

In the short-circuiting disaster prevention apparatus 200, when the short-circuit occurs, the coil of the input power source is increased by moving the connection point of the coil to which the input power is connected so that the short-circuit current is reduced in the direction of the input power And a short-circuit compensating device 210 for reducing the output voltage.

2, the short-circuit power converter 220 moves the connection point of the coil to which the input power is connected to supply the voltage generated at the time of short-circuit to the switch R1, as shown in FIG. 2 , The switch R1 operates to drive the contact R11, the contact R11 of the switch R1 supplies the switch R2 with the contact R23 of the switch R2 for interrupting the supply of the abnormal voltage to the load; It is preferable that the contact R21 of the switch R2 and the contact R22 of the switch R2 for driving the alarm generator to inform the outside of the short circuit state are provided preferably for continuing to operate the switch R2 without any change.

It is preferable that the short-circuit accident prevention device 200 further includes an alarm generator 230 for alarming occurrence of a short circuit in accordance with the alarm generation control electrical signal output by the contact R22 of the switch R2 .

In addition, when the alarm release switch for alarm release is operated by the manager after the alarm is generated by the alarm generator 230, the alarm disabling device 200 generates the alarm release signal, And an alarm release signal input unit 240 for recovering the alarm signal. The alarm release signal input unit 240 includes an alarm release switch as is well known.

In the disconnection prevention device in the power system according to the present invention configured as described above, after the power supplied from the KEPCO is supplied through the primary transformer, the power distribution line 100 of the power system is connected through the Y connection method Distribution boards and switchboards.

 At this time, when the load line is short-circuited, a spark occurs due to the short-circuit current, and the line is overheated. At that time, the circuit breaker operates to prevent the short-circuit accident from spreading. People and fire accidents happen and large accidents occur.

In order to prevent such an accident in advance, in the present invention, the harmonic wave generated in the load is always removed by the disaster prevention device 200 in the short circuit, and when the occurrence of a short circuit starts, the winding connection of the coil is immediately switched by the short- At the same time, the short-circuited power switch is cut off and at the same time, the short-circuit current is prevented from flowing to the power supply side.

More specifically, when power is supplied by the power system 100, the short-circuit power converter 220 operates to supply normal power to the load 300, and a short circuit occurs on the side of the load 300 The position of the input power supplied to the coils L1 and L2 provided in the short-circuit power converter 220 is automatically changed, and the voltage of the coil L3 L13 of the output power source is reduced to half of the steady voltage, L12 outputs an electric signal indicating the occurrence of a short circuit to the switch R1. For example, when an electric signal is output from the coil L2 L12, the occurrence of a short circuit (short circuit) can be detected.

When the switch R1 is operated, the contact R11 of the switch R1 is activated and the switch R2 is operated by the electric signal outputted from the contact R11 to cut off the electric power supplied through the contact R23 of the switch R2 or to connect the alarm generator to the contact R22 Or can perform the interruption and the alarm at the same time.

Assuming that the input voltage to be supplied is 220V, if the coil L1, L2, and L3 are wound on the short-circuit power converter 220 at a transforming ratio of 220V and 220V is applied to the power input terminal L11 and the power input / output terminal L13 3, the phase of the vector diagram 220-A at the normal power input is formed in the short-circuit power converter 220, and the power output terminal L12 provided in the power input / output terminal L13 and the coil L3 outputs the normal power of 220V, (300).

When the power supply output terminal L12 and the power supply input / output terminal L13 supplied to the load 300 are short-circuited, the power input / output terminal L13 becomes one conductor with the power output terminal L12, and the normal power input vector -B) is formed in the short-circuit power converter 220 and a voltage of 110 V is generated in each of the coils L1 and L2, and 110 V is also generated in the coil L3.

Therefore, it can be seen that 110V is generated in the power supply output terminal L14 and the power input / output terminal L13 which are the common terminal at the time of the short circuit, and it is recognized that the short circuit occurs simultaneously with the short circuit. Therefore, short- The coil on the power source side is increased to reduce the influence on the short-circuit current on the power source side, and if the short-circuit power converter 220 is selected for the load amount, the short-circuit current capacity is also decreased by the capacity of the transformer.

Therefore, even if a short circuit occurs on the load side, problems such as fire and electric shock due to overheating of the electric wire and momentary spark and over current can be prevented.

On the other hand, when the contact R11 of the switch R1 operates according to the electric signal outputted from the power output terminal L14 and the power input / output terminal L13 which is a common terminal, the contacts R21, R22 and R23 of the switch R2 are operated immediately The power cut-off R23 operation and the alarm generator 230 are immediately driven. The alarm generator 230 is activated to alarm the occurrence of a short circuit. In the present invention, the alarm is generated using a visual alarm and / or an audible alarm method.

If the administrator recognizes this in the state where a visual or audible alarm has occurred, it will quickly take follow-up measures, thereby preventing various accidents that may occur due to the occurrence of a short circuit.

In addition, the administrator can release alarms that occur as needed. For example, when the alarm release switch provided in the alarm release signal input unit 240 is operated, the alarm release signal input unit 240 generates an alarm release signal and transfers it to the switch R2.

When the alarm release signal is transmitted, the switch R2 stops operating, and the contacts R21, R22, and R23 associated with the switch R2 are also restored to start the power supply R23, stop the operation of the alarm generator 230, .

FIG. 5 is a flowchart showing a "disaster prevention method at a short circuit in a power system" according to a preferred embodiment of the present invention. When power is supplied to a short circuit correction device through a power system (distribution line) Supplying the normal power to the load side (S101);

When the resistance value of the load line decreases due to the occurrence of a short circuit on the side of the load 300, the electrical positions of the coils L1 and L2, which are windings connected to the power input terminals L11 and L13, Decreasing the short-circuit current on the power source side and the output voltage on the load side by increasing the L2 winding (S103);

The voltage generated at the power input / output common terminal L13 and the power output terminal L14 in the short circuit due to the electrical position change of the coils L1 and L2 is transmitted to the switch R1 provided in the short circuit correcting device 201 so that the switch R1 and the switch R1 contact R11 operate (S105);

The switch R1 contact R11 operates to transmit an electric signal to the switch R2 provided in the short circuit correcting device 201 so that the switch R2 and the contacts R21, R22 and R23 operate to stop the supply of the output power, and the alarm generator 230 Generating an alarm (S107)

When the alarm generator S107 generates an alarm, the alarm release request electric signal 240 is transmitted by the manager, and when the alarm is released and short-circuited by the alarm release request electric signal 240, (S109 to S111).

As shown in the figure, when the power is supplied by the power system (distribution line) in step S101, the load 300 having the short-circuit power converter 220 short-circuited when the load 300 is short- The electrical position of the coils L1 and L2 is changed using the line to prevent an accident caused by a short-circuit current that reduces the short-circuit current on the power source side and the output voltage on the load side.

The switch R1 is driven by the electric signal generated at the power output terminal L14 when the coil is short-circuited to change the electric position provided in the short-circuit power converter 220, and the switch R1 contact R11 operates to drive the switch R2, R21, R22, and R23 operate to stop supply of power to the load 300 in which a short circuit occurs, and generate an alarm signal (S105 to S107).

In addition, when a short circuit occurs, the alarm generator 230 is driven to generate an alarm for the occurrence of a short circuit by an audiovisual. After the alarm is generated by the administrator, The driving is stopped, and the generated alarm is released (S109 to S111).

That is, according to the present invention, when a short circuit occurs at the load side of the distribution line, an electric automatic position change in which the power input coil is increased by the faulty power converter is performed, and an electric disaster caused by a short- And short-circuit (short-circuit) is prevented to cause personal injury and fire accidents, and electrical equipment to be damaged. In addition, if a short circuit occurs, the load side power supply is immediately shut off, an alarm is generated to allow the manager to recognize the short circuit, and the manager can take a follow-up action promptly. It is possible to prevent accidents such as human accidents and electric fires or system failures.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined in the appended claims. And such changes are within the scope of the claims.

100 ... Power system (distribution line) 200 ... Disaster prevention device 210 in short circuit ... Short correction device 220 ... Short-circuit power converter 220-A ... The vector for the normal power input is 220-B ... The vector at the occurrence of a short circuit 230 ... Alarm generator 240 ... Alarm release signal input unit 300 ... Loads L1, L2, L3 ... Coil (inductance) L11 ... Power input terminal L12 ... Power output terminal L13 ... Power input / output terminal (common terminal) L14 ... Electrical signal output terminal R1 during short circuit ... Electronic switch (Magnet, SSR, etc.) R2 ... Electronic switch (Magnet, SSR, etc.) R11 ... R1 switch contacts R21, R22, R23 ... Switch contacts of R2

Claims (7)

And a short-circuit compensating device for reducing a supply-side short-circuit current by using the short-circuited fault power at the load side of the power distribution line provided in the power system and reducing the load-side output voltage to prevent an electric accident due to the short- (Short-circuit) in a power system. The disaster prevention device according to claim 1, wherein the short circuit correction device includes a short-circuit power converter that generates a short-circuit electric signal upon occurrence of a short circuit when the short circuit occurs. [3] The power converter according to claim 2, wherein the short-circuit power converter includes a coil (inductance) for canceling harmonics generated by causing the harmonics to flow once in phase with the normal phase, (Short-circuited) in the power system. The short-circuit power converter according to claim 2, wherein when a short circuit occurs on the load side, the ground potential difference of the short-circuited power is less than the potential difference of the power source to prevent a human accident caused by an electric shock if a short- Features a disaster prevention device when a short circuit occurs in the power system. The power converter according to claim 2, wherein the short-circuit power converter changes the electrical connection position of the coil connected to the power input terminal when the short circuit occurs, and distributes the voltage input to the power input terminal to the coil, And the output voltage of the load side is decreased while reducing the output voltage of the power system. The apparatus according to claim 1, wherein the short-
An alarm generator for indicating the occurrence of a short circuit according to an electrical signal output by the switch;
Further comprising an alarm release signal input unit for generating an alarm release electric signal and transmitting the alarm release electric signal to the short circuit correction device when an alarm release switch for alarm release is operated by the manager after the alarm is generated by the alarm generator Disconnection prevention device when a short circuit occurs. Disclosed is a method for disabling a short-circuit disaster when a short circuit occurs on a load side of a distribution line provided with a disaster prevention device in a short-circuit in a power system,
1) When the input power is supplied to the short circuit correcting device through the power line of the power system, the short circuit correcting device supplies normal power to the load side;
2) If the resistance value of the load line decreases due to the occurrence of a short circuit on the load side, the electrical connection position of the coil (inductance), which is a coil connected to the power input terminal to which the input power is supplied, Decreasing the voltage;
3) a step in which a switch is operated by transmitting a voltage generated at a power output terminal in a short circuit to a switch provided in the short circuit correcting device due to an electrical connection position change of the coil (inductance);
4) a step in which the switch provided in the short circuit correcting device operates to stop supplying output power or an alarm generator generates an alarm;
5) When an alarm is generated by the alarm generator, an alarm release request electric signal is transmitted by an administrator, and the alarm is released by an alarm release request electric signal. In the event that a short- How to prevent.

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