KR20210008806A - Electrical panel having instrument transformer with prevention of secondary terminal burnout - Google Patents

Abstract

A switchboard includes: a voltage transformer for transforming main power; a burnt smell detection unit for detecting generation of burnt smell inside the switchboard; and an instrument transformer connected between an isolator and the voltage transformer to convert the high-voltage main power supplied from a main power source into a low-pressure instrument voltage and instrument current usable in a meter. The instrument transformer includes: an instrument voltage transformer for converting a high voltage into a low voltage; a secondary terminal current measuring unit connected to a first terminal of a secondary winding of the instrument voltage transformer to measure the current; a short circuit preventing unit having one end connected to the first terminal of the secondary winding of the instrument transformer and the other end connected to a second terminal of the secondary winding of the instrument voltage transformer; and a controller that blocks the instantaneous short circuit of the secondary winding of the instrument transformer through the short circuit preventing unit when the current measured by the secondary terminal current measuring unit is checked as exceeding a reference current value, short-circuits the secondary winding of the instrument transformer through the short circuit preventing unit when a short circuit delay time has elapsed, short-circuits the secondary winding of the instrument current transformer when a burnt smell detection signal is provided from the burnt smell detection unit, and opens the secondary winding of the instrument transformer.

Description

Switchgear with an instrument transformer that prevents damage to the secondary terminal {ELECTRICAL PANEL HAVING INSTRUMENT TRANSFORMER WITH PREVENTION OF SECONDARY TERMINAL TERMINAL BURNOUT}

The present invention relates to a switchgear having an instrument transformer in which the secondary terminal is prevented from burning, and more particularly, to prevent burnout of a secondary terminal configured to normally perform the function of a relay in the event of an unexpected or abnormal condition in the switchboard. It relates to a switchgear having an instrument transformer.

In general, switchboards are equipped with switches, instruments, relays, etc. to supply high-voltage external power to the rated power required by each connected electronic device, and are installed in factories, buildings, hospitals, APT complexes, and various industrial facilities. Has become. In this switchgear, a complex configuration is made of wires and devices through which high voltage flows, and a number of current transformers (CTs) (ie, meter transformers) are provided for instrument devices. The instrument current transformer is a device for expanding the measurement range of an AC ammeter by obtaining a small current proportional to the number of windings from a large AC current.

An instrument transformer is a primary coil with a small number of windings and a secondary coil with a large number of windings wound around an iron core such as an instrument transformer, and an ammeter, a power meter, and a relay are connected to the secondary coil, and the primary coil and the secondary coil The current ratio of the current flowing through is inversely proportional to the number of turns of the primary and secondary coils.

In instrument current transformers, it is safe to short the secondary terminal, but it is dangerous to open it.This is because the primary current magnetizes all the cores when opening the secondary terminal, causing the core to saturate and generate heat. This is because there is a risk of coil damage, current transformer explosion, and electric shock.

Therefore, if the current circuit is opened inside or outside the ammeter, wattmeter, or relay connected to the secondary coil of the instrument transformer, or if the secondary coil of the instrument transformer is opened due to other reasons, it is immediately detected and the open state. A secondary open monitoring and protection device of the current transformer with the ability to immediately short-circuit the open secondary terminal is connected to the secondary side of the instrument transformer.

However, the secondary opening monitoring and protection device for instrument transformers can prevent damage to other measuring instruments connected to the secondary side by shorting the secondary side of the current transformer, but major electronic devices such as relays can also operate by shorting the secondary side. It is stopped, and there is a risk of a bigger accident because there is no way to notify the user or block even if an abnormal condition such as overvoltage or overcurrent occurs in the switchboard while the secondary is shorted.

In addition, there is a problem in that the instrument current transformer and the secondary side terminal open monitoring and protection device of the instrument current transformer and the instrument current transformer cannot be protected from an abnormal condition on the primary line due to the inflow or occurrence of overvoltage or overvoltage in the switchgear. There is a problem in that it is not possible to prevent damage to the instrument transformer due to malfunction of the secondary side terminal opening monitoring and protection device.

0001) Korean Registered Patent No. 10-1451389 (2014. 10. 08.) (Distribution board equipped with monitoring and protection device for open state of current transformer for instrumentation) 0002) Korean Patent Registration No. 10-1078905 (2011. 10. 26.) (Intelligent distribution board) 0003) Korea Utility Model Registration No. 20-0383776 (2005. 04. 30.) (Open detection device of the current transformer secondary terminal)

Accordingly, the technical problem of the present invention is to focus on this point, and an object of the present invention is to be able to actively protect instruments connected to an instrument current transformer and an instrument transformer, and poor contact on the secondary terminal connection line of the instrument current transformer. If there is a risk of opening, etc., the relay connected to the secondary terminal of the instrument transformer can be operated normally while preventing the opening of the secondary terminal of the instrument transformer, so that the function of the relay can be performed normally in the event of an unexpected or abnormal condition in the switchgear. It relates to a switchgear having an instrument transformer in which the secondary terminal is configured to be prevented from burning.

In order to realize the object of the present invention as described above, according to an embodiment, it is connected to a main power source that supplies power by contract power, supplies main power from the main power source to a load, a disconnector, a power fuse. , A switchgear having an instrument transformer in which burnout of a secondary terminal having a leading capacitor and a circuit breaker is prevented, comprising: a transformer for transforming the main power; A coal mine detector for detecting occurrence of a coal mine inside the switchboard; And an instrument transformer connected between the disconnector and the transformer to convert the high-voltage main power supplied from the main power source into a low-voltage instrument voltage and instrument current usable in a meter. Here, an instrument transformer (Voltage Transformer, VT, (or Potential Transformer, PT)) for converting a high voltage into a low voltage; A secondary terminal current measuring unit connected to the first terminal of the secondary winding of the instrument transformer (VT) to measure a current; A short-circuit prevention unit having one end connected to the first terminal of the secondary winding of the instrument transformer (VT) and the other end connected to the second terminal of the secondary winding of the instrument transformer (VT); And when it is checked that the current measured by the secondary terminal current measuring unit exceeds the reference current value, the secondary winding of the instrument transformer (VT) is immediately blocked from short-circuiting through the short-circuit prevention unit, and short-circuit delay. When time elapses, the secondary winding of the instrument transformer VT is short-circuited through the short-circuit prevention unit, and the secondary winding of the instrument current transformer CT is short-circuited as a bullet detection signal is provided from the bullet inner detection unit, It includes a controller for opening the secondary winding of the instrument transformer (VT).

In one embodiment, the inside of the coal detection unit, the inside detection sensor for detecting the inside of the coal inside the switchgear; A comparison unit that compares the output voltage according to the inside of the shot detected by the inside of the shot sensor with a reference voltage to determine whether or not inside of the shot occurs; And a smoothing unit for smoothing the output signal of the comparison unit and outputting the smoothing unit to the controller.

In one embodiment, the instrument transformer includes: a current transformer (CT) for converting a large current into a small current; A secondary terminal voltage measuring unit connected to the first terminal of the secondary winding of the instrument current transformer CT to measure voltage; And an opening prevention part having one end connected to the first terminal of the secondary winding of the instrument current transformer CT and the other end connected to the second terminal of the secondary winding of the instrument current transformer CT, wherein the When it is checked that the voltage measured by the secondary terminal voltage measuring unit exceeds the reference voltage value, the controller may open the secondary winding of the instrument current transformer CT through the opening prevention unit during an opening delay time. .

According to the switchboard having an instrument transformer in which the secondary terminal is prevented from being burned, it is connected to an instrument transformer provided in the switchboard to monitor the secondary side opening of the instrument transformer in real time, and when it detects the opening, it is notified to the user. It is possible to actively protect the instruments connected to the instrument transformer by shorting the secondary terminal, and it is connected to the instrument transformer provided in the switchboard to monitor the secondary short circuit of the instrument transformer in real time, and when a short circuit is detected, the user is notified. By opening the secondary terminal, the instruments connected to the instrument transformer can be actively protected. In addition, if there is a risk of opening such as poor contact on the secondary terminal connection line of the instrument transformer, the relay connected to the secondary terminal of the instrument transformer is prevented from being opened, while allowing the relay connected to the secondary terminal of the instrument transformer to operate normally. It enables the function of the relay to be normally performed in the event of an emergency or abnormal condition within the switchgear, and controls the power cut-off operation of a circuit breaker generally provided in the switchgear to open the secondary terminal of the instrument current transformer or the instrument current transformer when an abnormal condition occurs in the switchgear. Even the monitoring and protection devices can be self-protected, and the instrument transformer can be protected even when the secondary terminal opening monitoring and protection device of the instrument transformer malfunctions. In addition, the initial fire is detected by detecting the burning odor of the covering (hereinafter referred to as a dry sign of fire) along with the explosion sound, and based on this, the secondary winding of the instrument transformer is shorted and the secondary winding of the instrument transformer is opened. By doing so, it is possible to prevent damage to other measuring instruments connected to the secondary side, and to block the increase in the probability of fire occurrence inside the switchboard.

1 is a block diagram schematically illustrating a switchgear having an instrument transformer in which burnout of a secondary terminal is prevented according to the present invention.
FIG. 2 is a block diagram illustrating an instrument transformer having a terminal burnout prevention function shown in FIG. 1.
FIG. 3 is a flowchart illustrating an operation of the instrument transformer having a terminal burnout prevention function shown in FIG. 2.
4 is a block diagram schematically illustrating a switchgear having an instrument transformer in which damage to a secondary terminal is prevented according to another embodiment of the present invention.
5 is a configuration diagram for explaining an example of the inner bullet detection unit shown in FIG. 4.
6 is a configuration diagram for explaining an instrument transformer having a terminal burnout prevention function shown in FIG. 4.
7 is a flowchart illustrating the operation of the instrument transformer having a terminal burnout prevention function shown in FIG. 6.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. In the present invention, various modifications may be made and various forms may be applied, and specific embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific form disclosed, it should be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention.

In describing each drawing, similar reference numerals have been used for similar elements. In the accompanying drawings, the dimensions of the structures are shown to be enlarged than the actual size for clarity of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. These terms are used only for the purpose of distinguishing one component from another component. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may be referred to as a first component. Singular expressions include plural expressions unless the context clearly indicates otherwise.

In the present application, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof, does not preclude in advance the possibility of being added.

In addition, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. Terms as defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and should not be interpreted as an ideal or excessively formal meaning unless explicitly defined in this application. Does not.

1 is a block diagram schematically illustrating a switchgear having an instrument transformer in which damage to a secondary terminal is prevented according to an embodiment of the present invention.

Referring to FIG. 1, a switchgear 100 having an instrument transformer in which the secondary terminal is prevented from being burned according to an embodiment of the present invention includes a disconnector 110, a power fuse 120, and an instrument transformer (MOF, 130), a transformer 140, a circuit breaker 150, and a power control unit 200. Additionally, the switchgear 100 may include a lightning arrester 111, a fast condenser 141, and a circuit breaker (MCCB, 142).

The disconnector 110 serves to open and close a circuit in order to change the connection with the main power source 10 in a no-load state.

The power fuse 120 is connected between the disconnector 110 and the transformer 140 to protect various facilities of the switchgear from short circuits.

The instrument transformer 130 is for safely connecting a KEPCO meter to a place where high-voltage electricity is used, and is configured by combining a potential transformer (PT) and a current transformer (CT) in one device. The instrument transformer (VT) can be used for various instruments such as voltmeters, wattmeters, frequency meters, power factor meters, various relays, and indicators by lowering the voltage of a high-voltage circuit to low pressure. Such devices are called PT or VT, and the primary side is Although it depends on the voltage, the secondary side voltage is low, and a power fuse (PF) is installed on the primary side for the purpose of preventing the expansion of accidents by blocking fault currents such as coil burnout, and this fuse protects the PT. It is not the purpose, and when a PT malfunction occurs, the PF fuse is immediately cut off and serves to separate the PT from the high-voltage circuit. The instrumental current transformer (CT) is for viewing or using voltage, and CT is for viewing or using current, similar to the principle of PT. That is, it is a device that is connected in series to the circuit to reduce the high current of the high-voltage circuit to a small current, and is used as a power source for the current coil of the switchboard, the current coil of the power meter, and the trip coil of the overcurrent relay.

The instrument transformer 130 is connected between the disconnector 110 and the transformer 140, in particular, between the power fuse 120 and the transformer 140, and provides high-voltage main power supplied from the main power source 10. It converts into a low-pressure instrument voltage and instrument current usable in the meter 131. Here, the main power source 10 supplies power to the user, who is the customer. The main power source 10 is defined as a power supply source that supplies normal power to the load 20. Specifically, the main power source 10 may be commercial power supplied by a customer, that is, a power supplier that has signed a power supply contract with the user, or a separate power generation facility separated from the generator 210, for example, It may be a power generation facility such as solar power or wind power. That is, the main power source 10 may be defined as a power source that supplies power to the load 20 in a general state. More specifically, the main power source 10 may be KEPCO, but this does not limit the present invention. In addition, the main power source 10 is a subject that supplies power by a contract with the customer, and may be KEPCO. When the main power source 10 is KEPCO, a power contract is made with the customer by contract power and Can supply.

In this embodiment, in the instrument transformer 130, a terminal connected to the secondary winding of the instrument transformer has a burnout prevention function, and a terminal connected to the secondary winding of the instrument transformer has a burnout prevention function. That is, the instrument transformer 130 blocks the secondary winding of the instrument transformer from being immediately short-circuited due to abnormal conditions such as overcurrent, and short-circuits the secondary winding of the instrument transformer after the short-circuit delay time elapses. It prevents the secondary winding of the transformer or instrument transformer from burning out. In addition, the instrument transformer 130 blocks the immediate opening of the secondary winding of the instrument transformer due to abnormal conditions such as overvoltage, and opens the secondary winding of the instrument transformer after the opening delay time elapses. Or it prevents the secondary winding of the instrument current transformer from being burned.

The meter 131 calculates the total amount of power of the main power by using the meter voltage and meter current supplied from the meter transformer 130.

The transformer 140 converts high-voltage main power supplied from the main power source 10 into low-voltage main power. To this end, the transformer 140 has a high-voltage primary side connected to the 　 instrument transformer 130 or a power fuse 120, and a low-voltage secondary side connected to the load 20 through a circuit breaker 150.

The circuit breaker 150 is connected between the secondary side of the transformer 140 and the load 20, and serves to prevent a current greater than the rated current from flowing through the load 20.

The power control unit 200 detects the amount of power supplied to the load 20 from the main power source 10 or the amount of power used by the load 20, and according to the determination of the use of excess power or power failure, the generator 210 It performs driving control of and switching between the load 20 and the power sources 10 and 210. Specifically, the power control unit 200 allows the main power to be supplied to the load 20 when using power within the contracted power, and when excessive power use is detected or a power failure occurs, the power generated by the generator 210 is transferred to the load 20. Be supplied.

To this end, the power control unit 200 detects the amount of power used by the main power or the load 20 from the main power source, and determines the use of excess power or a power outage. In addition, the power control unit 200 drives the generator 210 to supply generated power when using excess power or power failure, and supplies power by the generator 210 to part or all of the load 20 according to the driving of the generator. The power sources 10 and 210 are switched to achieve this.

In addition, when the use of excess power or the power failure is canceled, the power control unit 200 switches again so that the load 20 connected to the generator 210 receives main power and stops driving the generator 210.

The generator 210 is connected to a part or all of the load 20 by the power control unit 200 when a power outage (or power failure) or excessive power use occurs of the main power source 10, and supplies power to the connected load 20 . Such a generator 210 may be an emergency generator installed in the customer or a generator installed and operated by the user's selection, but the present invention is not limited by what is presented.

The load 20 is connected to the main power source 10 or the generator 210 by the power control unit 200 and receives power from the connected power sources 10 and 210. Here, the load 20 is supplied from the main power source 10 to receive the main power converted to low voltage by the transformer, and for this purpose, the load 20 is connected to the transformer 140 to receive the low voltage main power by the transformer 140. It is supplied. However, for convenience of explanation, the description will proceed as receiving the main power from the main power source, and the meaning of receiving the main power includes a process in which the main power is transformed by the transformer 140. In addition, the low voltage in the present invention is because the voltage of the secondary side has a generally lower voltage than that of the primary side when comparing the primary side and the secondary side of the transformer, and does not refer to a specific voltage. In addition, if necessary, the secondary side voltage may be higher than that of the primary side, and the primary side is not limited to a low voltage, and for convenience of explanation, it is assumed that the secondary side of the transformer 140 is lower than the primary side. I decided to proceed.

As shown in FIG. 1, the load 20 includes a main power source 10 and a second load 22 that is maintained connected regardless of whether excess power is used or whether or not, and a generator ( It may be divided into a first load 21 connected to 210). Here, when the capacity of the generator 210 is sufficiently secured so that the power generation can be supplied to all the loads 20 of the user, the configuration of the second load 22 may be omitted. On the other hand, when the capacity of the generator 210 is smaller than the power consumption of the entire load, the load 20 is divided as shown, so that only some of the loads (the first load 21) are driven by the generator 210. can do. To this end, the first load 21 may be calculated based on an important load requiring continuous driving or a partial load 20 that generates excess power use, but this does not limit the present invention.

The arrester 111 discharges some or all of the abnormal voltage generated or induced in the power system, and after the discharge, blocks the conductive path to restore the insulation of the line, thereby protecting the power system and power distribution facilities. To this end, the arrester 111 may be connected to the secondary side of the disconnector 110 by a circuit breaker.

Consisting of further comprising a leading capacitor 141 connected to the secondary side of the transformer 140 and a lead capacitor 141 and a mold case current breaker (MCCB) 142 for connecting or blocking the secondary side of the transformer 140 Can be.

FIG. 2 is a block diagram illustrating an instrument transformer having a terminal burnout prevention function shown in FIG. 1.

2, an instrument transformer having a terminal burnout prevention function includes a current transformer (CT) 310, a potential transformer (PT) 320, and a secondary terminal voltage measuring unit ( 330), a secondary terminal current measurement unit 340, an opening prevention unit 350, a short circuit prevention unit 360, and a controller 370.

The instrument current transformer 310 converts a large current into a small current. Specifically, the instrument current transformer 310 is provided on the main line of the switchboard and converts a large current of alternating current flowing through the main line (primary line) into a small current of alternating current proportional to the number of windings and converts it into a secondary line. Turn it on.

The instrument transformer 320 converts a high voltage into a low voltage. Specifically, the instrument transformer 320 is provided on the main line of the switchgear and converts a large AC voltage that energizes the main line into a small AC voltage proportional to the number of windings to energize the secondary line.

The secondary terminal voltage measuring unit 330 is connected to the first terminal of the secondary winding of the instrument current transformer 310 to measure the variation of the voltage value of the secondary line due to failure of electronic devices or poor contact, and the controller ( 370). Specifically, the secondary terminal voltage measuring unit 330 is provided on the main line of the switchgear and converts a large current of AC flowing on the main line (primary line) into a small current of AC proportional to the number of windings. The voltage of the secondary terminal of the instrument current transformer 310 that is energized to the vehicle line is measured in real time, and the measured voltage value of the secondary terminal of the current transformer is transmitted to the controller 370.

In general, a large current of tens to thousands of amperes flows on the main line of the switchboard, but a small current of 5 amperes mostly flows through the secondary line of the instrument current transformer 310, which is converted through the instrument current transformer 310. Electronic devices such as a relay, an ammeter, or a power meter are connected on the secondary line below the instrument current transformer 310 through which a small current of 5 amperes is applied, and the secondary terminal voltage measuring unit 330 The variation of the voltage value of the secondary line due to contact failure, etc. is measured and output to the controller 370.

The secondary terminal current measuring unit 340 is connected to the first terminal of the secondary winding of the instrument transformer 320 to measure the current. Specifically, the secondary terminal current measuring unit 340 is provided on the main line of the switchgear and converts a large AC voltage that energizes the main line (primary line) into a small AC voltage proportional to the number of windings. The current of the secondary terminal of the instrument transformer 320 that is energized to the vehicle line is measured in real time, and the measured current value of the secondary terminal of the transformer is transmitted to the controller 370.

The opening prevention part 350 has one end connected to the first terminal of the secondary winding of the instrument current transformer 310 and the other end connected to the second terminal of the secondary winding of the instrument current transformer 310, and the controller ( It is switched in response to the control of 370). Specifically, when receiving the secondary terminal short signal from the controller 370, the opening prevention unit 350 opens the secondary terminal of the instrument transformer 320, thereby preventing a secondary line short circuit. It is possible to prevent in advance the iron core saturation heat generation of the instrument transformer 320 that may be generated by the instrument transformer 320, an explosion accident of the instrument transformer 320, or an electric shock accident.

The short-circuit prevention unit 360 has one end connected to the first terminal of the secondary winding of the instrument transformer 320 and the other end connected to the second terminal of the secondary winding of the instrument transformer 320, and the controller ( It is switched in response to the control of 370). Specifically, when the short-circuit prevention unit 360 receives the secondary terminal open signal from the controller 370, the secondary terminal of the instrument current transformer 310 is short-circuited, and accordingly, the secondary line is opened. It is possible to prevent in advance an iron core saturation heat generation of the instrument current transformer 310, an explosion accident, or an electric shock accident of the instrument current transformer 310 that may be generated.

The controller 370 receives user input data such as a reference voltage level, a reference current level, an open delay time, a short delay time, a reset signal, and a test signal from the outside. In addition, the controller 370 compares the voltage measured at the first terminal of the secondary winding of the instrument transformer based on the reference voltage level provided from the outside to prevent the opening of the secondary winding of the instrument transformer. Set the timing of the time. In addition, the controller 370 compares the current measured at the first terminal of the secondary winding of the instrument transformer based on the reference current level provided from the outside to prevent the short circuit of the secondary winding of the instrument transformer. Set the timing of the time.

In addition, when the controller 370 checks that the voltage measured by the secondary terminal voltage measurement unit 330 exceeds the reference voltage value, the 2 of the instrument current transformer 310 through the open prevention unit 350 during the open delay time. The secondary winding is blocked, and when the opening delay time elapses, the secondary winding of the instrument current transformer 310 is opened.

In addition, when the controller 370 checks that the current measured by the secondary terminal current measuring unit 340 exceeds the reference current value, the controller 370 passes through the short-circuit prevention unit 360 during the short-circuit delay time. The secondary winding is blocked, and when the short-circuit delay time elapses, the secondary winding of the instrument transformer 320 is short-circuited.

In addition, the controller 370 may immediately output an alarm signal to notify the user of the faulty contact occurring on the secondary line of the instrument transformer or the instrument transformer or electronic devices connected to the secondary line. have.

The instrument transformer having a terminal burnout prevention function according to the present invention may further include a wireless communication unit (not shown) for wirelessly notifying a user that an abnormal state such as overvoltage or overcurrent has occurred. In this case, the controller 370 wirelessly transmits the occurrence of an abnormal condition to the user through the wireless communication unit.

The instrument transformer having a terminal burnout prevention function according to the present invention may further include a display unit (not shown) for indicating that an abnormal state such as overvoltage or overcurrent has occurred. In this case, the controller 370 displays occurrence of an abnormal state through the display unit.

The controller 370 can notify the user through the wireless communication unit (not shown) that an abnormal condition such as overvoltage or overcurrent has occurred, and display that an abnormal condition such as overvoltage or overcurrent has occurred through the display unit (not shown). May be.

In general, when the secondary winding of the instrument transformer CT provided in the instrument transformer is immediately opened, all secondary currents act as excitation currents, causing overvoltage to induce insulation breakdown, causing the instrument transformer to burn out. However, according to the present invention, when a voltage higher than the reference voltage value is measured in the secondary winding of the instrument transformer, the secondary winding is not immediately opened, and the secondary winding is prevented from being immediately opened during the opening delay time set by the user. After that, the user is notified and the secondary winding is opened when the open delay time elapses, thereby actively protecting the instruments connected to the instrument transformer.

In addition, when an overcurrent flows through a load connected to the secondary winding of an instrument transformer (PT or VT) typically provided in an instrument transformer, the overvoltage is induced, causing insulation breakdown, and the instrument transformer is burnt. In particular, the instrument transformer must be opened because a short circuit current flows when the secondary side is shorted. That is, this is because R becomes 0 and the current becomes infinite at I=V/R.

However, according to the present invention, when a current larger than the reference current value is measured in the secondary winding of the instrument transformer, the secondary winding is not immediately short-circuited, and the secondary winding is prevented from being immediately shorted during the short-circuit delay time set by the user. After that, the user is notified, and when the short-circuit delay time elapses, the secondary winding is short-circuited to actively protect the instruments connected to the instrument transformer.

Then, the operation of the instrument transformer having the terminal burnout prevention function shown in FIG. 2 will be briefly described below.

FIG. 3 is a flowchart illustrating an operation of the instrument transformer having a terminal burnout prevention function shown in FIG. 2.

2 and 3, the secondary terminal current measuring unit 340 is connected to the secondary winding of the instrument transformer 320 for converting a high voltage to a low voltage to measure the current (step S110). The measured current is provided to the controller 370.

Subsequently, the controller 370 checks whether the measured current exceeds the reference current value (step S112). Here, the reference current value may be input by a user.

When it is checked that the current measured in step S112 exceeds the reference current value, the controller 370 uses the instrument transformer through the short-circuit prevention unit 360 during the short-circuit delay time to prevent burnout of the instrument transformer 320. 320) is prevented from being immediately shorted (step S114). Here, the short-circuit delay time may be input by the user.

Subsequently, the controller 370 checks whether the short-circuit delay time has elapsed (step S116).

If it is checked that the short-circuit delay time has elapsed in step S116, the controller 370 short-circuits the secondary winding of the instrument transformer 320 (step S118).

On the other hand, if it is checked that the current measured in step S112 does not exceed the reference current value, the secondary terminal voltage measuring unit 330 is connected to the secondary winding of the instrument current transformer 310 for converting a large current into a small current. The voltage is measured (step S120).

Subsequently, the controller 370 checks whether the measured voltage exceeds the reference voltage value (step S122). Here, the reference voltage value may be input by a user.

If it is checked that the voltage measured in step S122 exceeds the reference voltage value, the controller 370 is configured to prevent the instrument current transformer 310 from being burned through the opening prevention unit 350 during the opening delay time. The secondary winding of 310) is blocked from being opened immediately (step S124).

Subsequently, the controller 370 checks whether the open delay time has elapsed (step S126).

If it is checked that the open delay time has elapsed in step S126, the controller 370 opens the secondary winding of the instrument current transformer 310 (step S128).

In the above, measuring the current in the secondary winding of the instrument transformer (VT) and then measuring the voltage of the secondary winding of the instrument transformer (CT) has been described, but after measuring the voltage of the secondary winding of the CT It is also possible to measure the current in the secondary winding. In addition, the step of measuring the current of the secondary winding of the VT and the step of measuring the voltage of the secondary winding of the CT may be performed simultaneously.

As described above, according to the present embodiment, it is connected to an instrument current transformer provided in the switchgear and monitors the secondary side opening of the instrument current transformer in real time, and when the open is detected, it is notified to the user and the secondary terminal is shorted. The instruments connected to the instrument transformer can be actively protected.

In addition, it is connected to the instrument transformer installed in the switchgear and monitors the secondary side short of the instrument transformer in real time, and when a short is detected, it notifies the user and opens the secondary terminal to actively protect the instruments connected to the instrument transformer. I can.

In addition, if there is a risk of opening such as poor contact on the secondary terminal connection line of the instrument transformer, the relay connected to the secondary terminal of the instrument transformer is prevented from being opened, while allowing the relay connected to the secondary terminal of the instrument transformer to operate normally. It enables the function of the relay to be normally performed in the event of an emergency or abnormal condition within the switchgear, and controls the power cut-off operation of a circuit breaker generally provided in the switchgear to open the secondary terminal of the instrument current transformer or the instrument current transformer when an abnormal condition occurs in the switchgear. Even the monitoring and protection devices can be self-protected, and the instrument transformer can be protected even when the secondary terminal opening monitoring and protection device of the instrument transformer malfunctions.

On the other hand, a lot of various electric wires are arranged in the switchgear. If overcurrent or overvoltage is continuously applied to the electric wires, a leakage current is generated, and the generated leakage current may lead to fire. In addition, stripped wires can cause short circuits or short circuits, which can lead to fire. The burning odor of the covering (hereinafter, burnt), along with the sound of an explosion, is considered a dry sign of a fire. Detecting the inside of the cladding can be a very important factor in detecting and extinguishing an initial fire.

In consideration of these points, a switchboard that can detect an initial fire through internal detection to respond to the initial fire and prevent the spread of fire while preventing burnout of the secondary terminal of the instrument transformer is implemented as follows with reference to the drawings. Explained in an example.

4 is a block diagram schematically illustrating a switchgear having an instrument transformer in which damage to a secondary terminal is prevented according to another embodiment of the present invention. In particular, there is shown a switchboard having an instrument transformer in which the secondary terminal is prevented from being burned by having a bullet detection function.

4, the switchgear 100 having an instrument transformer in which the secondary terminal is prevented from being burned according to another embodiment of the present invention includes a disconnector 110, a power fuse 120, and an instrument transformer (MOF, 130), a transformer 140, a circuit breaker 150, a bullet detection unit 160 and a power control unit 200. Additionally, the switchgear 100 may include a lightning arrester 111, a fast condenser 141, and a circuit breaker (MCCB, 142). The switchboard 100 having an instrument transformer in which the secondary terminal shown in FIG. 4 is prevented from being burned out has an instrument transformer in which the secondary-side terminal shown in FIG. Since it is the same as the switchboard 100, the same reference numerals are given, and detailed descriptions thereof are omitted.

The coal mine detection unit 160 includes an odorant sensor, detects the occurrence of the coal mine (or burning odor) inside the switchboard 100, and provides the detected coal mine detection signal to the instrument transformer 130. Here, the burnt smell is the burning smell of the covering of the electric wire. In other words, the faulty contact of the wire is that resistance occurs at the connection point of the wire (circuit branching, etc.), resulting in a flow failure. The contact between the wires, that is, the +,- electrodes, which are the conductors of the wires, collide, leading to burnout of the watt-hour meter and further to electric fire.

5 is a configuration diagram for explaining an example of the inside of the bullet detection unit 160 shown in FIG.

Referring to Figures 4 and 5, the inside detection unit 160 is configured to include the inside detection sensor 162, a pull-down resistor (R31), a comparison unit 164, a pull-up resistor (R34) and a smoothing unit 166. .

The pull-down resistor R31 includes a grounded end and the other end connected to one end of the bullet inner detection sensor 162.

The bullet interior detection sensor 162 includes one end connected to the power voltage terminal (Vcc) and the other end connected to the other end of the pull-down resistor R31, and detects the interior of the interior of the switchboard 100 to change according to the occurrence of the interior of the bullet. The voltage Vref1 is provided to the comparison unit 164.

The comparator 164 includes a first resistor R32, a second resistor R33, and a comparator COMP. The comparator COMP receives the output voltage provided from the bullet inner sensor 162, that is, the first reference voltage Vref1 according to the detected inner shell, through a negative input terminal, and receives the first resistance R32 and the second resistance. The second reference voltage Vref2, which is voltage-divided by R33), is input through a positive input terminal and provides a comparison signal according to whether or not a bullet is generated to the smoothing unit 166.

The pull-up resistor R34 includes one end connected to the power voltage terminal Vcc and the other end connected to the output terminal of the comparator 164.

The smoothing unit 166 includes a third resistor (R35) and a first capacitor (C12), and smoothes the output signal of the comparison unit 164 to provide a smoothed signal, that is, a bullet detection signal to the instrument transformer 130. Print.

6 is a configuration diagram for explaining an instrument transformer having a terminal burnout prevention function shown in FIG. 4.

4, 5 and 6, an instrument transformer having a terminal burnout prevention function includes an instrument current transformer (CT) 310, an instrument transformer (VT) 320, and a secondary terminal voltage measuring unit ( 330), a secondary terminal current measurement unit 340, an opening prevention unit 350, a short circuit prevention unit 360, and a controller 370. The instrument transformer having the terminal burnout prevention function shown in FIG. 6 is the same as the instrument transformer having the terminal burnout prevention function shown in FIG. 2 except that the bulletin detection signal is provided by the bulletin detection unit 160. Reference numerals are assigned and detailed descriptions thereof are omitted.

The controller 370 receives user input data such as a reference voltage level, a reference current level, an open delay time, a short delay time, a reset signal, and a test signal from the outside. In addition, the controller 370 compares the voltage measured at the first terminal of the secondary winding of the instrument transformer based on the reference voltage level provided from the outside to prevent the opening of the secondary winding of the instrument transformer. Set the timing of the time. In addition, the controller 370 compares the current measured at the first terminal of the secondary winding of the instrument transformer based on the reference current level provided from the outside to prevent the short circuit of the secondary winding of the instrument transformer. Set the timing of the time.

In addition, when the controller 370 checks that the voltage measured by the secondary terminal voltage measurement unit 330 exceeds the reference voltage value, the 2 of the instrument current transformer 310 through the open prevention unit 350 during the open delay time. The secondary winding is blocked, and when the opening delay time elapses, the secondary winding of the instrument current transformer 310 is opened.

In addition, when the controller 370 checks that the current measured by the secondary terminal current measuring unit 340 exceeds the reference current value, the controller 370 passes through the short-circuit prevention unit 360 during the short-circuit delay time. The secondary winding is blocked, and when the short-circuit delay time elapses, the secondary winding of the instrument transformer 320 is short-circuited.

In addition, the controller 370 short-circuits the secondary winding of the instrument current transformer 310 by controlling the opening prevention unit 350 when the coal interior detection signal is provided by the coal mine detection unit 160, and controls the short circuit prevention unit 360 The secondary winding of the instrument transformer 320 is opened.

In addition, the controller 370 controls the opening prevention unit 350 if the inside detection signal is provided by the inside detection unit 160 even while blocking the opening of the secondary winding of the instrument transformer 310 during the opening delay time. The secondary winding of the transformer 310 is short-circuited, and the secondary winding of the instrument transformer 320 is opened by controlling the short circuit prevention unit 360.

In addition, the controller 370 controls the opening prevention unit 350 if a bullet detection signal is provided from the bullet detection unit 160, even while blocking the secondary winding of the instrument transformer 320 during the short circuit delay time. The secondary winding of the transformer 310 is short-circuited, and the secondary winding of the instrument transformer 320 is opened by controlling the short circuit prevention unit 360.

Then, in the following, the operation of the instrument transformer having a terminal burnout prevention function shown in FIG. 6 will be briefly described.

7 is a flowchart illustrating the operation of the instrument transformer having a terminal burnout prevention function shown in FIG. 6.

6 and 7, the controller 370 checks whether or not the inside of the bullet is detected (step S210). Here, the bullets may be detected by the bullet inside detection unit 160. When the inside of the shot is detected, the inside detection unit 160 may provide the inside of the shot detection signal to the controller 370.

If it is checked in step S210 that the bullet inside is detected, the controller 370 controls the opening prevention unit 350 to short-circuit the secondary winding of the instrument current transformer 310, and controls the short circuit prevention unit 360 to control the instrument transformer. The secondary winding of 320 is opened (step S212). In this way, in the event of an initial fire sign when the inside is detected, the secondary winding of the instrument transformer 310 is short-circuited and the secondary winding of the instrument transformer 320 is opened, thereby preventing damage to other measuring instruments connected to the secondary side. . In particular, if the secondary terminal of the instrument current transformer 310 is kept open, the primary current magnetizes all the iron cores, thereby saturating the iron core and generating heat. This causes the temperature of the instrument transformer including the instrument current transformer 310 The risk of fire is further increased by increasing the temperature or increasing the temperature inside the switchboard equipped with the instrument transformer. However, according to this embodiment, by shorting the secondary winding of the instrument current transformer 310, it is possible to prevent an increase in the probability of a fire occurrence inside the switchgear.

If it is checked in step S210 that the inside of the bullet is not detected, the secondary terminal current measuring unit 340 measures the current by being connected to the secondary winding of the instrument transformer 320 for converting a high voltage to a low voltage (step S214). The measured current is provided to the controller 370.

Then, the controller 370 checks whether the measured current exceeds the reference current value (step S216). Here, the reference current value may be input by a user.

When it is checked that the current measured in step S216 exceeds the reference current value, the controller 370 uses the instrument transformer through the short-circuit prevention unit 360 during the short-circuit delay time to prevent burnout of the instrument transformer 320. 320) is blocked from being immediately shorted (step S218). Here, the short-circuit delay time may be input by the user.

Next, it is checked whether or not the inside of the bullet is detected (step S220). Here, the bullet inside may be detected by the bullet inside detection unit 160. When the inside of the shot is detected, the inside detection unit 160 may provide the inside of the shot detection signal to the controller 370.

If it is checked that the inside of the bullet is detected in step S220, the secondary winding of the instrument transformer 310 is short-circuited by controlling the opening prevention unit 350, and the second winding of the instrument transformer 320 is controlled by controlling the short circuit prevention unit 360. The secondary winding is opened (step S224).

If it is checked that the inside of the bullet is not detected in step S220, the controller 370 checks whether the short-circuit delay time has elapsed (step S226).

If it is checked that the short-circuit delay time has elapsed in step S226, the controller 370 controls the short-circuit prevention unit 360 to short the secondary winding of the instrument transformer 320 (step S228).

On the other hand, if it is checked that the current measured in step S216 does not exceed the reference current value, the secondary terminal voltage measurement unit 330 is connected to the secondary winding of the instrument transformer 310 for converting a large current into a small current. The voltage is measured (step S230).

Subsequently, the controller 370 checks whether the measured voltage exceeds the reference voltage value (step S232). Here, the reference voltage value may be input by a user.

If it is checked that the voltage measured in step S232 exceeds the reference voltage value, the controller 370 uses the instrument current transformer through the open prevention unit 350 during the open delay time to prevent burnout of the instrument current transformer 310 ( The secondary winding of 310) is blocked from being opened immediately (step S234).

Next, it is checked whether or not the inside of the bullet is detected (step S236). Here, the bullet inside may be detected by the bullet inside detection unit 160. When the inside of the shot is detected, the inside detection unit 160 may provide the inside of the shot detection signal to the controller 370.

If it is checked that the inside of the bullet is detected in step S236, the secondary winding of the instrument transformer 310 is short-circuited by controlling the opening prevention unit 350, and the short circuit prevention unit 360 is controlled to The secondary winding is opened (step S238).

If it is checked that the inside of the bullet has not been detected in step S236, the controller 370 checks whether the open delay time has elapsed (step S240).

If it is checked that the opening delay time has elapsed in step S240, the controller 370 controls the opening prevention unit 350 to open the secondary winding of the instrument current transformer 310 (step S242).

In the above, measuring the current in the secondary winding of the instrument transformer (VT) and then measuring the voltage of the secondary winding of the instrument transformer (CT) has been described, but after measuring the voltage of the secondary winding of the CT It is also possible to measure the current in the secondary winding. In addition, the step of measuring the current of the secondary winding of the VT and the step of measuring the voltage of the secondary winding of the CT may be performed simultaneously.

Typically, instrument transformers that perform the role of measuring the amount of electricity for power supply and demand simply measure the amount of electricity for supply and demand by using an instrument transformer (CT) and an instrument transformer (VT), but do not have a monitoring function for overheating. . Therefore, it is not possible to prevent a fire caused by overheating of the instrument transformer (VT), and if a fire occurs due to overheating of the instrument transformer (VT), the components of the front and rear ends may also become inoperative. Due to this, enormous damage is expected. Here, overheating of the instrument transformer (VT) is caused by deterioration of the insulating oil, deterioration of the windings of the instrument transformer (VT), inflow of high frequency/harmonic waves, surge inflow, etc., and this causes the instrument transformer (VT) to If overheated, a fire will occur. In addition, a lot of various electric wires are arranged in the switchgear. If an overcurrent or overvoltage is continuously applied to the electric wires, a leakage current is generated and the generated leakage current may lead to a fire. In addition, stripped wires can cause short circuits or short circuits, which can lead to fire.

However, according to the present invention, the initial fire is detected by detecting the burning odor of the covering (hereinafter referred to as the inside of the coal), which is regarded as a dry sign of the fire along with an explosion sound or arc, and based on this, the secondary winding of the instrument transformer is short-circuited. By opening the secondary winding of the transformer, damage to other measuring instruments connected to the secondary can be prevented, and the probability of fire occurrence inside the switchboard can be prevented from increasing.

Although the above has been described with reference to examples, it is understood that those skilled in the art may variously modify and change the present invention without departing from the spirit and scope of the present invention described in the following claims. You can understand.

100: switchgear 110: disconnector
111: lightning arrester 120: power fuse
130: instrument transformer 140: transformer
141: true phase capacitor 142: wiring breaker
150: circuit breaker 160: bullet detection unit
162: bullet detection sensor 164: comparison unit
166: smoothing unit 200: power control unit
310: instrument transformer 320: instrument transformer
330: secondary terminal voltage measurement unit 340: secondary terminal current measurement unit
350: opening prevention part 360: short circuit prevention part
370: controller

Claims (3)

In a switchgear connected to a main power source supplying power by contract power, supplying main power from the main power source to a load, and having a disconnector, a power fuse, a lead capacitor and a circuit breaker,
A transformer converting the main power;
A coal mine detector for detecting occurrence of a coal mine inside the switchboard; And
An instrument transformer connected between the disconnector and the transformer to convert the high-voltage main power supplied from the main power source into a low-voltage instrument voltage and instrument current available in a meter, wherein the instrument transformer comprises:
An instrument transformer that converts high voltage to low voltage (Voltage Transformer, VT, (or Potential Transformer, PT));
A secondary terminal current measuring unit connected to the first terminal of the secondary winding of the instrument transformer (VT) to measure a current;
A short-circuit prevention unit having one end connected to the first terminal of the secondary winding of the instrument transformer (VT) and the other end connected to the second terminal of the secondary winding of the instrument transformer (VT); And
If it is checked that the current measured by the secondary terminal current measuring unit exceeds the reference current value, the secondary winding of the instrument transformer (VT) is immediately blocked from short-circuiting through the short-circuit prevention unit, and short-circuit delay time When this elapses, the secondary winding of the instrument transformer VT is short-circuited through the short-circuit prevention unit, and the secondary winding of the instrument current transformer CT is short-circuited as the bullet inner detection signal is provided from the bullet inner detection unit. A switchboard having an instrument transformer in which damage to a secondary terminal is prevented, comprising a controller for opening a secondary winding of an instrument transformer (VT). The method of claim 1, wherein the bullet detection unit,
A coal mine detection sensor that detects a coal mine inside the switchgear;
A comparison unit that compares the output voltage according to the inside of the shot detected by the inside of the shot sensor with a reference voltage to determine whether or not inside of the shot occurs; And
And a smoothing unit for smoothing the output signal of the comparison unit and outputting it to the controller. The method of claim 1, wherein the instrument transformer,
Current Transformer (CT) for converting a large current into a small current;
A secondary terminal voltage measuring unit connected to the first terminal of the secondary winding of the instrument current transformer CT to measure voltage; And
One end is connected to the first terminal of the secondary winding of the instrument current transformer (CT) and the other end is connected to the second terminal of the secondary winding of the instrument current transformer (CT), further comprising an opening prevention unit,
When it is checked that the voltage measured by the secondary terminal voltage measuring unit exceeds the reference voltage value, the controller blocks the immediate opening of the secondary winding of the instrument current transformer CT through the opening prevention unit. , A switchgear having an instrument transformer preventing burnout of a secondary terminal, characterized in that the secondary winding of the instrument current transformer (CT) is opened when the opening delay time elapses.

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