KR102663907B1 - The Apply installation type monitoring system for sensing open state of the secondary terminal of a current transformer - Google Patents

Abstract

The present invention relates to a monitoring system applicable to secondary opening of an instrument current transformer, and more specifically, to a secondary opening of the instrument current transformer and an instrument transformer installed in a power circuit connected to the instrument transformer and the instrument transformer. By monitoring the secondary short circuit in real time, the user is notified when each open or short circuit is detected, and the instruments connected to the current transformer can be actively protected by short-circuiting the secondary terminal of the instrument current transformer. In addition, instrument current transformer 2 By making the judgment conditions for whether or not the breaker open more detailed, the secondary terminal of the instrument current transformer can be opened under precise conditions, and the loss in operation and management of the power circuit due to the opening of the ineffective secondary terminal of the instrument current transformer can be minimized. It is easier to detect the occurrence of an abnormal condition in a power circuit and its cause. By controlling the power-off operation of a generally provided circuit breaker, when an abnormal condition occurs within the power circuit, the instrument current transformer or the instrument current transformer secondary open installation applicable monitoring system is installed. This relates to a secondary open installation type monitoring system for instrument current transformers that can protect the instrument current transformer even when the instrument current transformer secondary open installation type monitoring system malfunctions.
The monitoring system applicable to secondary open installation of instrument current transformers according to the present invention includes a circuit breaker (CB) that cuts off power when overcurrent or overvoltage occurs, and an instrument current transformer (CT, Current Transformer), an instrument transformer (PT, Potential Transformer), and a relay electrically connected to each secondary terminal connection line of the instrument current transformer and the instrument transformer. In the instrument current transformer secondary opening installation applicable monitoring system that detects an abnormal state of the power circuit and monitors the opening of the secondary terminal of the instrument current transformer, secondary blocking of the instrument current transformer to the three-phase power supply A secondary terminal voltage measuring unit that measures the voltage values of each secondary terminal of the instrument and instrument transformer; A secondary terminal current measuring unit that measures the current value of the secondary terminal of the instrument current transformer for the three-phase power supply; A predetermined standard open-circuit voltage value and a predetermined standard open-circuit current value of each of the secondary terminals of the instrument current transformer for the three-phase power supply are input through the user input unit, and a predetermined standard open-circuit current imbalance value of the secondary terminal of the instrument current transformer is input. And, receiving the blocking delay time, receiving the measured voltage values of each of the secondary terminal of the instrument transformer and the secondary terminal of the instrument transformer for the three-phase power from the secondary terminal voltage measurement unit, and receiving the secondary terminal voltage measurement unit. A control unit that receives measured current values of each secondary terminal of the instrument current transformer for a three-phase power source from the current measuring unit and outputs a secondary terminal opening signal to the outside; an instrument current transformer short-circuiting unit that receives a secondary terminal open signal from the control unit and short-circuits the secondary terminal of the instrument current transformer; And, a reset button that receives a reset command from the user and cancels the short circuit of the instrument current transformer, wherein the control unit determines each measured voltage value of the instrument current transformer secondary terminal for the three-phase power supply. If it is higher than the standard open-circuit voltage value and each measured current value is lower than the standard open-circuit current value, output a secondary terminal open signal to the outside; The current imbalance value for the secondary terminal of the instrument current transformer is calculated through each measured current value of the secondary terminal of the instrument current transformer for the three-phase power input from the secondary terminal current measurement unit, and the calculated The current imbalance value is higher than the reference open-circuit current imbalance value, and the measured voltage value of the secondary terminal of the instrument current transformer for at least one phase of the three-phase power supply is higher than the reference open-circuit voltage value, and the measured voltage value of the secondary terminal of the instrument current transformer is higher than the reference open-circuit voltage value. If the measured current value is lower than the reference open current value, output a secondary terminal open signal to the outside; When the secondary terminal opening signal is output to the outside, if a reset command is not received from the user through the reset button during the input blocking delay time, blocking the circuit breaker is operated; It is characterized by

Description

{The Apply installation type monitoring system for sensing open state of the secondary terminal of a current transformer}

The present invention relates to a monitoring system applicable to secondary opening of an instrument current transformer, and more specifically, to a secondary opening of the instrument current transformer and an instrument transformer installed in a power circuit connected to the instrument transformer and the instrument transformer. It monitors the secondary short circuit in real time and notifies the user when each open or short circuit is detected, and short-circuits the secondary terminal of the instrument current transformer to actively protect the instruments connected to the current transformer.

In addition, the judgment conditions for whether or not the secondary terminal of the instrument current transformer is open are more detailed, so that the secondary terminal of the instrument current transformer is opened under precise conditions, and the operation and management loss of the power circuit due to the opening of the invalid secondary terminal of the instrument current transformer is reduced. can be minimized, and it is easier to detect the occurrence of an abnormal condition in the power circuit and its cause. By controlling the power-off operation of a commonly provided circuit breaker, a secondary open instrument transformer or instrument current transformer can be installed when an abnormal condition occurs in the power circuit. It is about a secondary open installation type monitoring system for instrument current transformers that can protect the applicable monitoring system itself and can protect the instrument current transformer even when the monitoring system malfunctions. .

In general, devices that make up power circuits such as switchboards and switchboards equipped with switches, instruments, relays, etc. to receive high-voltage external power and convert it into the rated power required by each connected electronic device are used in factories, buildings, and hospitals. , is being installed in APT complexes and various industrial facilities.

This power circuit has a complex configuration of high-voltage wires and devices, and is equipped with many current transformers (CTs) for instrumentation devices. A current transformer is a type of transformer and is a device to expand the measurement range of an alternating current ammeter by obtaining a small current proportional to the number of turns from a large current of alternating current. A current transformer is made by winding a primary coil with a small number of turns and a secondary coil with a large number of turns on an iron core like a transformer. An ammeter, wattmeter, and relay are connected to the secondary coil, and the current flowing in the primary and secondary coils is measured. The current ratio is inversely proportional to the number of turns of the primary and secondary coils. A current transformer is different from a transformer. It is safe to short the secondary terminal, but it is dangerous to open it. This is because when the secondary terminal is opened, the primary current magnetizes all the iron cores, saturating the iron core and generating heat. This is because there is a risk of damage to the coil, explosion of the current transformer, and electric shock. Therefore, if the current circuit is opened inside or outside the ammeter, power meter, or relay connected to the secondary coil of the current transformer, or if the secondary coil of the current transformer is opened due to other reasons, this is immediately detected and the open state is blocked. That is, a current transformer secondary terminal open monitoring and protection device, which has the function of immediately shorting the open secondary terminal, is connected to the secondary side of the current transformer.

However, such a conventional current transformer secondary terminal open monitoring and protection device can prevent damage to other measuring instruments connected to the secondary side by short-circuiting the secondary side of the current transformer, but the voltage value measured on the secondary side is simply the standard in the normal state. If it is higher than the voltage value, it is considered open and the secondary is short-circuited. Even if the secondary side is not open, the secondary side is short-circuited if the measured voltage value on the secondary side is higher than the reference voltage value in the normal state. There is a problem that invalid short-circuiting occurs frequently, there is a problem that the operation and management loss of the power circuit increases due to an invalid secondary short-circuit, and it is difficult to analyze the exact cause of the short-circuit and prepare corresponding countermeasures. There is a problem in that it is difficult to detect the effects and occurrence of abnormal conditions due to malfunction of the power system including the power circuit.

In addition, the conventional current transformer secondary terminal open monitoring and protection device can prevent damage to other measuring instruments connected to the secondary side by short-circuiting the secondary side of the current transformer, but the primary line due to the inflow or occurrence of overvoltage or overvoltage in the distribution panel. There is a problem in that the current transformer and the current transformer secondary terminal opening monitoring and protection device itself cannot be protected from an abnormal state, and there is a problem in preventing damage to the current transformer due to malfunction of the current transformer secondary terminal opening monitoring and protection device. .

Domestic Registered Patent No. 10-0955719 (Title of invention: ‘Overheating prevention of current transformer and secondary terminal open detection device’) Domestic Registered Patent No. 10-2329199 (Title of invention: ‘Converter measuring line safety abnormality detection system’)

The present invention was developed to solve the above problems, and monitors the secondary terminal of the instrument current transformer in real time more closely through the current value, voltage value, and number of contact defects of the secondary terminal of the instrument current transformer. By making the opening conditions of the secondary terminal of the instrument current transformer more detailed, it is possible to minimize the short-circuit operation on the secondary side of the instrument current transformer, and reduce the operation and management loss of the power circuit due to the ineffective secondary short-circuit. To enable,

In addition, it makes it easy to analyze the exact cause of short-circuit operation on the secondary side of the instrument current transformer and prepare solutions accordingly, and to detect the effects and occurrence of abnormal conditions due to malfunction of the power system including the relevant power circuit. , It prevents the instrument current transformer or the instrument current transformer secondary opening installation application type monitoring system from being damaged due to the influence of surge, overvoltage, or overcurrent coming from the outside, and the instrument current transformer secondary opening. It prevents damage to the current transformer due to failure or malfunction of the installed monitoring system itself.

In one form of the present invention to solve the above-described problems, a circuit breaker (CB, Circuit Breaker) that cuts off power when overcurrent or overvoltage occurs, and a current transformer (CT, Current Transformer) provided to measure power for a three-phase power supply. ), an instrument transformer (PT, Potential Transformer), and a relay electrically connected to each secondary terminal connection line of the instrument transformer and the instrument transformer. In the instrument current transformer secondary opening installation applicable monitoring system that detects an abnormal state of the power circuit and monitors the opening of the secondary terminal of the instrument current transformer, the secondary terminal of the instrument current transformer for the three-phase power supply and A secondary terminal voltage measuring unit that measures the voltage value of each secondary terminal of the instrument transformer; a secondary terminal current measuring unit that measures the current value of the secondary terminal of the instrument current transformer for a three-phase power supply; A predetermined standard open-circuit voltage value and a predetermined standard open-circuit current value of each of the secondary terminals of the instrument current transformer for the three-phase power supply are input through the user input unit, and a predetermined standard open-circuit current imbalance value of the secondary terminal of the instrument current transformer is input. And, receiving the blocking delay time, receiving the measured voltage values of each of the secondary terminal of the instrument transformer and the secondary terminal of the instrument transformer for the three-phase power from the secondary terminal voltage measurement unit, and receiving the secondary terminal voltage measurement unit. A control unit that receives measured current values of each secondary terminal of the instrument current transformer for a three-phase power source from the current measuring unit and outputs a secondary terminal opening signal to the outside; an instrument current transformer short-circuiting unit that receives a secondary terminal open signal from the control unit and short-circuits the secondary terminal of the instrument current transformer; And, a reset button that receives a reset command from the user and cancels the short circuit of the instrument current transformer, wherein the control unit determines each measured voltage value of the instrument current transformer secondary terminal for the three-phase power supply. If it is higher than the standard open-circuit voltage value and each measured current value is lower than the standard open-circuit current value, output a secondary terminal open signal to the outside; The current imbalance value for the secondary terminal of the instrument current transformer is calculated through each measured current value of the secondary terminal of the instrument current transformer for the three-phase power input from the secondary terminal current measurement unit, and the calculated The current imbalance value is higher than the reference open-circuit current imbalance value, and the measured voltage value of the secondary terminal of the instrument current transformer for at least one phase of the three-phase power supply is higher than the reference open-circuit voltage value, and the measured voltage value of the secondary terminal of the instrument current transformer is higher than the reference open-circuit voltage value. When the measured current value is lower than the reference open current value, output a secondary terminal open signal to the outside; When the secondary terminal opening signal is output to the outside, if a reset command is not received from the user through the reset button during the input blocking delay time, blocking the circuit breaker is operated; It provides a monitoring system applicable to secondary open installation of instrument current transformers.

In the monitoring system applicable to secondary open installation of a current transformer for instrumentation according to the present invention, it further includes a warning sound unit that receives a warning sound signal from the control unit and generates a warning sound to the outside, wherein the control unit generates a warning sound through a user input unit. The predetermined standard warning contact failure voltage value, standard open contact failure voltage value, standard contact failure current value, and standard contact failure zero-phase electric current value of each of the secondary terminals of the instrument current transformer for the three-phase power supply, Receive input of a predetermined range of the standard contact defect phase difference value and the standard contact defect current imbalance value; The measured voltage value of the secondary terminal of the instrument current transformer for at least one phase of the three-phase power supply is higher than the standard warning poor contact voltage value, and the measured current value of the secondary terminal of the instrument current transformer is higher than the reference poor contact current value. , Calculate the zero-phase current value for the secondary terminal of the instrument current transformer through each measured current value of the secondary terminal of the instrument current transformer for the three-phase power input from the secondary terminal current measurement unit, and calculate If the calculated zero-phase current value is lower than the reference poor-contact zero-phase current value and the calculated current imbalance value is lower than the reference poor-contact current imbalance value, or the second blocking of the instrument transformer for one phase of the three-phase power supply If the difference between the current phase value of the voltage phase value of the current transformer and the secondary terminal of the instrument current transformer is smaller than a predetermined range of the reference defective contact phase difference value, outputting a warning sound signal to the outside; After outputting the warning sound signal to the outside, the control unit opens the secondary terminal to the outside when the measured voltage value of each secondary terminal of the instrument current transformer for the three-phase power source is higher than the reference open contact failure voltage value. A signal can be output,

Preferably, when the control unit outputs the secondary terminal opening signal to the outside and does not receive a reset command from the user through the reset button during the input blocking delay time, and operates the circuit breaker to block. , the blocking operation of the circuit breaker can be released only when a reset command is input from the user through the reset button.

The monitoring system applicable to the secondary open installation of the instrument current transformer according to the present invention monitors the secondary terminal of the instrument current transformer in more detail in real time through the current value, voltage value, and number of contact defects of the secondary terminal of the instrument current transformer. can be monitored, and the opening conditions of the secondary terminal of the instrument current transformer can be further refined to minimize the short-circuit operation on the secondary side of the instrument current transformer, and reduce the operation and management loss of the power circuit due to the invalid secondary short-circuit. It is possible to easily analyze the exact cause of the short-circuit operation on the secondary side of the instrument current transformer and prepare a solution accordingly, and detect the effects and occurrence of abnormal conditions due to malfunction of the power system including the relevant power circuit.

In addition, it is possible to prevent the instrument current transformer or the instrument current transformer secondary open installation applicable monitoring system from being damaged due to surge, overvoltage, or overcurrent that may flow into or be generated within the power circuit. Even if the monitoring system itself for secondary open installation is broken or malfunctions, damage to the instrument current transformer and instrument transformer can be prevented in advance.

1 is a system configuration diagram showing a monitoring system applicable to secondary open installation of an instrument current transformer according to the present invention;
Figure 2 is a graph showing a judgment method for detecting openness of the secondary terminal of the instrument current transformer in the monitoring system applicable to secondary open installation of the instrument current transformer according to the present invention;
Figure 3 is a circuit diagram showing the operation control logic for determining the opening of the secondary terminal of the instrument current transformer in the monitoring system applicable to the secondary opening of the instrument current transformer according to the present invention;
Figure 4 is a graph showing an embodiment of a judgment method for detecting poor contact of the secondary terminal of the instrument current transformer in the monitoring system applicable to secondary open installation of the instrument current transformer according to the present invention;
Figure 5 is a circuit diagram showing an embodiment of the operation control logic that detects poor contact of the secondary terminal of the instrument current transformer in the monitoring system applicable to secondary open installation of the instrument current transformer according to the present invention;
Figure 6 is a graph showing another embodiment of a judgment method for detecting poor contact of the secondary terminal of the instrument current transformer in the monitoring system applicable to secondary open installation of the instrument current transformer according to the present invention;
Figure 7 is a circuit diagram showing another embodiment of the operation control logic for detecting poor contact of the secondary terminal of the instrument current transformer in the monitoring system applicable to secondary open installation of the instrument current transformer according to the present invention;
Figure 8 is a graph showing a judgment method for detecting voltage imbalance of the secondary terminal of the instrument transformer in the monitoring system applicable to secondary open installation of the instrument transformer according to the present invention;
Figure 9 is a circuit diagram showing the operation control logic for detecting contact voltage imbalance of the secondary terminal of the instrument transformer in the monitoring system applicable to secondary open installation of the instrument transformer according to the present invention; and,
Figure 10 is a system configuration diagram showing another embodiment of a monitoring system applicable to secondary open installation of an instrument current transformer according to the present invention.

Hereinafter, embodiments of the present invention in which the above object can be realized in detail will be described with reference to the attached drawings. In describing the present embodiments, the same names and symbols are used for the same components, and additional description accordingly is omitted below.

Figure 1 is a system configuration diagram showing a monitoring system applicable to secondary open installation of a current transformer for instrumentation according to the present invention, and Figure 2 is a diagram showing a monitoring system applicable to a secondary open installation of a current transformer for instrumentation according to the present invention, and current transformer 2 for instrumentation. It is a graph showing the determination method for detecting the openness of the primary terminal, and Figure 3 shows the operation control logic that determines the opening of the secondary terminal of the metering current transformer in the monitoring system applicable to the secondary opening of the metering current transformer according to the present invention. This is a circuit diagram showing:

The monitoring system applicable to secondary open installation of instrument current transformers according to the present invention includes a circuit breaker (CB) that cuts off power when overcurrent or overvoltage occurs, and an instrument current transformer (CT, Current Transformer), an instrument transformer (PT, Potential Transformer), and a relay electrically connected to each secondary terminal connection line of the instrument current transformer and instrument transformer. In the instrument current transformer secondary opening installation applicable monitoring system that detects an abnormal state of the power circuit and monitors the secondary terminal opening of the instrument current transformer, as shown in FIG. 1, largely three phases A secondary terminal voltage measuring unit that measures voltage values for each of the a, b, and c phases of the instrument current transformer and the instrument transformer for the power supply, and the secondary terminal of the instrument current transformer for the three-phase power supply. A secondary terminal current measurement unit that measures the current values for each of the a-phase, b-phase, and c-phase, receives the measured values from each of the measurement units, and inputs the initial setting data, that is, the 3-phase power supply, through the user input unit. Receives a predetermined standard open-circuit voltage value, standard open-circuit current value, and standard open-circuit current imbalance value of the secondary terminal of the instrument current transformer, and generates a control signal according to the judgment conditions using the inputted initial setting data and each measured value. A secondary opening of the instrument current transformer, which includes a control unit that outputs an output to the outside, a short circuit unit of the instrument current transformer that receives a control signal from the control unit and short-circuits the secondary terminal of the instrument current transformer, and a reset button that receives a reset command from the user. The installation-type monitoring system includes a circuit breaker (CB) that opens and closes the power supply to block overcurrent or overvoltage that comes from outside or occurs within the power circuit, and a current transformer (CT) for power measurement. And, it is provided in a power circuit that includes an instrument transformer (PT, Potential Transformer).

As shown in FIG. 1, the secondary terminal voltage measuring unit is provided on the main line of the power circuit and uses three-phase AC power that energizes the main line (primary line), that is, phase a, phase b, and phase c. The voltage of the secondary terminal of the instrument current transformer (CT, Current Transformer), which converts the large current of each phase into a small alternating current proportional to the number of turns and passes it to the secondary line. The voltage of the secondary terminal of the current-energizing instrument transformer (PT, Potential Transformer) is measured in real time, and the measured voltage values of the secondary terminals of the instrument transformer and transformer are transmitted to the control unit.

In general, a large current ranging from tens of amperes to thousands of amperes flows on the main line of the power circuit, but a small current of 5 amperes mostly flows in the secondary line of the instrument current transformer, and the 5 amperes converted through the instrument current transformer Electronic devices such as relays, ammeters, and power meters are connected to the secondary line below the instrument current transformer through which a small current of Changes in the voltage value of the secondary line are measured and output to the control unit.

As shown in FIG. 1, the secondary terminal current measuring unit measures the current value of the secondary terminal of the instrument current transformer for each phase of the three-phase AC power source, that is, the a phase, the b phase, and the c phase, and Pass it to

As shown in FIG. 1, the control unit receives a predetermined reference open-circuit voltage value and a predetermined reference open-circuit current value of each of the secondary terminals of the instrument current transformer for the three-phase power source from the user through the user input unit, Receives a predetermined standard open current imbalance value of the secondary terminal of the instrument current transformer, and measures each of the secondary terminal of the instrument current transformer and the secondary terminal of the instrument transformer for a three-phase power source from the secondary terminal voltage measurement unit. Receives the voltage value, receives the measured current value of each secondary terminal of the instrument current transformer for the three-phase power source from the secondary terminal current measurement unit, and sends a secondary terminal open signal to the outside through predetermined judgment conditions. It will be printed.

In the instrument current transformer secondary opening installation applicable monitoring system according to the present invention, measured values are used to determine the opening of the instrument current transformer secondary terminal in more detail, and whether a predetermined condition of the corresponding measurement value is satisfied is detected, Through the measurement values input from the various measuring devices, it is possible to detect whether the secondary terminal of the instrument current transformer is open in more detail, and to reduce invalid short-circuit operation of the secondary terminal of the instrument current transformer.

The instrument current transformer short-circuiting unit shorts the secondary terminal of the instrument current transformer when a secondary terminal open signal is input from the control unit, and as a result, the instrument current transformer that may be caused by secondary line opening is shorted. It is possible to prevent saturation heat of the iron core of the current transformer, explosion of the current transformer, or electric shock.

Before the secondary terminal of the instrument current transformer is opened, as shown in FIG. 2, the current value of the secondary terminal of the instrument current transformer usually decreases and the voltage value increases, and the instrument current transformer of the present invention using this phenomenon A simplified circuit diagram of the operation control logic that determines the opening of the secondary terminal is shown in Figure 3, where la, lb, lc and Va, Vb, and Vc are instrument current transformers for each phase of the three-phase power supply. It represents the measured current value and measured voltage value of the secondary terminal, and Iub represents the current imbalance value of the secondary terminal of the instrument current transformer. Among the three phases of a phase, b phase, and c phase, the measured current value of the instrument current transformer secondary terminal is the highest. The current imbalance value (Iub) is calculated by setting the measured current value of the large phase as Imax and the smallest measured current value of the phase as Imin.

As shown in FIG. 3, the control unit determines that each measured voltage value of the secondary terminal of the instrument current transformer for the three-phase power source is higher than the predetermined reference open-circuit voltage value preset and input through the user input unit, and each When the measured current value is lower than the standard open current value, output a secondary terminal open signal to the outside, or measure each secondary terminal of the instrument current transformer for the three-phase power input from the secondary terminal current measurement unit. The current imbalance value for the secondary terminal of the instrument current transformer is calculated through the above-described method using the current value, and the calculated current imbalance value is higher than the reference open current imbalance value, and at least one of the three-phase power supply If the measured voltage value of the secondary terminal of the instrument current transformer for the corresponding phase is higher than the reference open-circuit voltage value, and the measured current value of the secondary terminal of the instrument current transformer for the corresponding phase is lower than the reference open-circuit current value, The secondary terminal open signal is output to the outside, that is, to the short-circuiting part of the instrument current transformer, and the event contents of the control operation of the control unit are stored and can be used as analysis data when outputting the secondary terminal open signal, making it easier. It is possible to find the cause of the secondary terminal open signal and prevent its recurrence.

The reset button receives a reset command from the user and releases the secondary terminal short circuit of the instrument current transformer short circuit unit. That is, when the instrument current transformer shorting unit receives a secondary terminal open signal from the control unit and shorts the secondary terminal of the instrument current transformer, the user causes the instrument current transformer shorting unit to short-circuit the secondary terminal. After identifying the cause and taking appropriate measures according to the identified cause, pressing the reset button releases the short-circuit in the secondary terminal of the instrument current transformer short circuit, thereby stably disconnecting the instrument current transformer and the secondary line. You can operate electronic devices.

In the monitoring system applicable to the secondary opening of the instrument current transformer according to the present invention, the control unit outputs the secondary terminal open signal to the instrument current transformer short-circuiting section to short-circuit the secondary line. If the control unit does not receive a reset command from the user through the reset button during the blocking delay time input from the user, the control unit operates to cut off the circuit breaker provided on the main line of the power circuit, thereby disconnecting the secondary terminal of the instrument current transformer. If follow-up measures cannot be taken immediately because the cause of the short-circuit cannot be found, or the instrument current transformer secondary open installation application type monitoring system malfunctions, or if follow-up measures cannot be taken immediately due to the user's absence for a long period of time. It is possible to prevent damage accidents of the instrument current transformer or the instrument current transformer secondary open installation type monitoring system from abnormal conditions of unknown cause, etc., and the instrument current transformer secondary open installation application type monitoring system can be prevented in advance. Helps prevent additional accidents or losses due to malfunction.

Preferably, after the control unit outputs the secondary terminal open signal to the instrument current transformer short-circuiting unit, it does not receive a reset command from the user through the reset button during the blocking delay time input from the user, and turns off the circuit breaker. In the case of a blocking operation, the blocking operation of the breaker can be released only when a reset command is input from the user through the reset button, so that overcurrent, overvoltage, surge, and abnormal current in the power circuit are usually prevented from external sources. In addition to the case where the circuit breaker is blocked due to inflow or generation from If the above circuit breaker is shut off due to failure to receive a command, it is determined that an abnormal condition of unknown cause has occurred, and protection of the above-mentioned instrument current transformer or secondary open installation applicable monitoring system and secondary open installation of instrument current transformer are provided. In order to prevent additional accidents or losses due to malfunction of the applicable monitoring system, an interlock function is performed to release the blocking operation of the circuit breaker only after the user confirms that the cause of the circuit breaker's blocking operation has been removed through the reset button. make it possible

Figure 4 is a graph showing an example of a judgment method for detecting poor contact of the secondary terminal of the instrument current transformer in the secondary open installation application monitoring system for the instrument current transformer according to the present invention, and Figure 5 is a graph showing an embodiment of the present invention. This is a circuit diagram showing an embodiment of the operation control logic that detects poor contact of the secondary terminal of the instrument current transformer in a monitoring system applicable to secondary open installation of the instrument current transformer.

In general, poor contact of the secondary terminal of an instrument current transformer is caused by various factors such as ambient humidity, temperature, fine dust, vibration, and equipment aging. Overheating occurs due to increased contact resistance due to incomplete contact of the circuit connection part, and severe damage occurs. In this case, there is a risk of fire. In the case of the monitoring system applicable to the secondary open installation of the instrument current transformer according to the present invention, the poor contact status of the secondary terminal of the instrument current transformer is detected in three stages. In the first stage, only a warning alarm sounds to the outside, and in the second stage, the above-mentioned If the measured voltage value of the secondary terminal of the instrument current transformer is higher than the standard open contact failure voltage value after the first stage warning alarm, a secondary terminal open signal is output to the outside.

That is, as shown in FIGS. 4 and 5, the power circuit abnormality monitoring system according to the present invention further includes a warning sound unit that receives a warning sound signal from the control unit and generates a warning sound to the outside, The control unit outputs a predetermined standard warning poor contact voltage value, a standard open contact defective voltage value, a standard contact defective current value, and a standard contact defective zero phase current (Zero-) of each of the secondary terminals of the instrument current transformer for the three-phase power through the user input unit. Phase Electric Current) value, a predetermined range of the reference bad contact phase difference value, and the reference bad contact current imbalance value are input, and the measured voltage value of the secondary terminal of the instrument current transformer for at least one phase of the three-phase power supply is the standard. It is higher than the warning poor contact voltage value and the measured current value of the secondary terminal of the instrument current transformer is higher than the reference poor contact current value,

The zero-phase current value for the secondary terminal of the instrument current transformer is calculated through each measured current value of the secondary terminal of the instrument current transformer for the three-phase power input from the secondary terminal current measurement unit, and the calculated If the zero-phase current value is lower than the reference poor-contact zero-phase current value and the calculated current imbalance value is lower than the reference poor-contact current imbalance value, or the secondary terminal of the instrument transformer for one phase of the three-phase power supply When the difference between the voltage phase value and the current phase value of the secondary terminal of the instrument current transformer is smaller than the predetermined range of the reference defective contact phase difference value, a warning sound signal is output to the outside.

In FIGS. 3 and 5, la, lb, lc, Va, Vb, and Vc represent the measured current value and measured voltage value of the secondary terminal of the instrument current transformer for each phase of the three-phase power supply, and 3Io represents the instrument current transformer. It represents the zero-phase current value of the secondary terminal and can be calculated as 3Io = Ia + Ib + Ic, and usually has a value of 0.1 to 5A. θ(I) represents the current phase value of the secondary terminal of the instrument current transformer, and Iub represents the current imbalance value of the secondary terminal of the instrument current transformer, as described above.

In addition, after outputting the warning sound signal to the outside, the control unit outputs the warning sound signal to the outside and, when the measured voltage value of each secondary terminal of the instrument current transformer for the three-phase power source is higher than the reference open contact failure voltage value, blocks the second terminal to the outside. Now, an open signal is output.

Figure 6 is a graph showing another example of a judgment method for detecting poor contact of the secondary terminal of the instrument current transformer in the instrument current transformer secondary open installation application type monitoring system according to the present invention, and Figure 7 is a graph showing another embodiment of the present invention. This is a circuit diagram showing another embodiment of the operation control logic that detects poor contact of the secondary terminal of the instrument current transformer in the monitoring system applicable to secondary open installation of the instrument current transformer. In FIGS. 6 and 7, DELTA V is Indicates the voltage increase rate of the secondary terminal of the instrument current transformer, COUNT I is the current of the secondary terminal of the instrument current transformer, COUNT V is the voltage of the secondary terminal of the instrument current transformer, and COUNT N/T is poor contact for T seconds at the secondary terminal of the instrument current transformer. Indicates the number of occurrences.

In the monitoring system applicable to secondary open installation of the instrument current transformer according to the present invention, in the third step of detecting a poor contact state of the secondary terminal of the instrument current transformer, as shown in FIGS. 6 and 7, instrument current transformer 2 The phenomenon of foreign substances in the circuit breaker and the resistance of incomplete connections increasing with time is taken into consideration, and the decision is made by counting the rate of voltage increase over time (Delta V) and the number of instantaneous arc occurrences due to incomplete connection of terminals.

That is, in the monitoring system applicable to secondary open installation of the instrument current transformer according to the present invention, it is formed to further include a contact failure occurrence count measurement unit that measures the number of occurrences of contact failure of the secondary terminal of the instrument current transformer with respect to the three-phase power supply, and , Here, the number of occurrences of contact failure of the secondary terminal of the instrument current transformer may be measured by counting the instantaneous arc generated by incomplete connection of the secondary terminal of the instrument current transformer, among various conventional methods.

The control unit determines the voltage increase rate value for a predetermined time for the secondary terminal of the instrument current transformer through the measured voltage values of each secondary terminal of the instrument current transformer for the three-phase power input from the secondary terminal voltage measurement unit. Calculate, input the predetermined standard voltage increase rate value, standard contact failure maximum current value, and standard contact failure occurrence count value of each secondary terminal of the instrument current transformer for the 3-phase power source through the user input unit, and input the 3-phase power supply For at least one phase, the measured current value of the secondary terminal of the instrument current transformer is lower than the reference maximum contact failure current value and higher than the reference failure contact current value, and the calculated voltage increase rate value is greater than the reference voltage increase rate value. If it is high, output a secondary terminal open signal to the outside, or

The control unit determines that the number of occurrences of contact defects received during a predetermined period of time from the contact failure frequency measurement unit is greater than the reference number of occurrences of contact defects, and the measured voltage value of the secondary terminal of the instrument transformer for one phase of the three-phase power supply. If the measured current value of the secondary terminal of the instrument current transformer is higher than the reference warning poor contact voltage value and is lower than the reference maximum bad contact current value and higher than the reference bad contact current value, output a secondary terminal open signal to the outside. Thus, the third step of detecting poor contact of the secondary terminal of the instrument current transformer is performed.

Figure 8 is a graph showing a judgment method for detecting voltage imbalance of the secondary terminal of the instrument transformer in the secondary open installation application monitoring system for the instrument current transformer according to the present invention, and Figure 9 is a graph showing the instrument current transformer according to the present invention. This is a circuit diagram showing the operation control logic that detects the contact voltage imbalance of the secondary terminal of the instrument transformer in the secondary open installation application type monitoring system.

The monitoring system applicable to the secondary open installation of the instrument transformer according to the present invention determines voltage imbalance by detecting the zero phase voltage value of the secondary terminal of the instrument transformer, and the control unit determines voltage imbalance through the user input unit. Receive a predetermined reference zero-phase voltage value for the secondary terminal of the instrument transformer, and measure each voltage of the secondary terminal of the instrument transformer for the three-phase power input from the secondary terminal voltage measurement unit. The zero-phase voltage value for the secondary terminal of the instrument transformer is calculated through the value, and when the calculated zero-phase voltage value is higher than the reference zero-phase voltage value, a warning sound signal is output to the outside.

Preferably, when the control unit externally outputs a control signal according to each event, each measurement data and input data through the user input unit are stored in the storage, and the cause of the control signal output by the control unit is determined based on the stored data. It allows for easy analysis and prevents the same event from occurring again.

Figure 10 is a system configuration diagram showing another embodiment of a monitoring system applicable to secondary open installation of an instrument current transformer according to the present invention. Preferably, as shown in Figure 10, abnormal current generated inside and outside the power circuit A ground line is formed to remove the ground line to the ground, and a ground line measuring unit is additionally configured to measure the voltage value of the ground line, wherein the control unit receives the voltage value of the ground line measured from the ground line measuring unit, Receives a predetermined ground reference voltage value and ground alarm delay time that appear in the normal state of the power circuit from the user, outputs an alarm signal when the voltage value of the ground line is higher than the ground reference voltage value, and outputs an alarm signal when the ground line voltage value is higher than the ground reference voltage value. If the voltage value of is higher than the ground reference voltage value continues during the ground alarm delay time, the breaker can be operated to cut off abnormal currents such as overcurrent, overvoltage, and surge flowing from the external power supply. B It is possible to prevent damage or malfunction of the instrument current transformer and the instrument current transformer secondary open installation applicable monitoring system due to abnormal conditions occurring within the power circuit, and safely protect the power circuit from unexpected abnormal currents. Make sure you can do it and keep it stable at all times.

In this way, the monitoring system applicable to secondary open installation of the instrument current transformer according to the present invention monitors the instrument current transformer in real time more closely through the current value, voltage value, and number of contact defects of the secondary terminal of the instrument current transformer. The secondary terminal can be monitored, and the opening conditions of the secondary terminal of the instrument current transformer can be further refined to minimize the operation of an invalid short circuit on the secondary side of the instrument current transformer, and the operation and management of the power circuit due to an invalid secondary short circuit. It can reduce losses, make it easier to analyze the exact cause of short-circuit operation on the secondary side of the instrument current transformer and prepare solutions accordingly, and detect the effects and occurrence of abnormal conditions due to malfunction of the power system including the relevant power circuit. You can,

In addition, it is possible to prevent the instrument current transformer or the instrument current transformer secondary open installation applicable monitoring system from being damaged due to surge, overvoltage, or overcurrent that may flow into or be generated within the power circuit. Even if the monitoring system itself for secondary open installation is broken or malfunctions, damage to the instrument current transformer and instrument transformer can be prevented in advance.

Although several embodiments have been described above as examples, it is obvious to those skilled in the art that the present invention can be embodied in various other forms without departing from the spirit and scope thereof.

Accordingly, the above-described embodiments are to be regarded as illustrative and not restrictive, and all embodiments within the appended claims and their equivalents are intended to be included within the scope of the present invention.

Claims (3)

A circuit breaker (CB) that cuts off the power when overcurrent or overvoltage occurs, a current transformer (CT) provided to measure power for a three-phase power supply, a potential transformer (PT), and the above instruments. It is provided in a power circuit that includes a relay that is electrically connected to the secondary terminal connection lines of each of the power transformer and the instrument transformer, detects an abnormal state of the power circuit, and detects the abnormal state of the instrument current transformer. In the instrument current transformer secondary opening installation applicable monitoring system that monitors secondary terminal opening,

A secondary terminal voltage measuring unit that measures the respective voltage values of the secondary terminal of the instrument transformer and the secondary terminal of the instrument transformer with respect to the three-phase power supply;
A secondary terminal current measuring unit that measures the current value of the secondary terminal of the instrument current transformer for the three-phase power supply;
A predetermined standard open-circuit voltage value and a predetermined standard open-circuit current value of each of the secondary terminals of the instrument current transformer for the three-phase power supply are input through the user input unit, and a predetermined standard open-circuit current imbalance value of the secondary terminal of the instrument current transformer is input. And, receiving the blocking delay time, receiving the measured voltage values of each of the secondary terminal of the instrument transformer and the secondary terminal of the instrument transformer for the three-phase power from the secondary terminal voltage measurement unit, and receiving the secondary terminal voltage measurement unit. A control unit that receives measured current values of each secondary terminal of the instrument current transformer for a three-phase power source from the current measuring unit and outputs a secondary terminal opening signal to the outside;
an instrument current transformer short-circuiting unit that receives a secondary terminal open signal from the control unit and short-circuits the secondary terminal of the instrument current transformer; and,
It is configured to include a reset button that receives a reset command from the user and releases the short circuit of the instrument current transformer short circuit,

The control unit,
When each measured voltage value of the secondary terminal of the instrument current transformer for a three-phase power supply is higher than the standard open-circuit voltage value and each measured current value is lower than the standard open-circuit current value, a secondary terminal open signal is output to the outside. ;
The current imbalance value for the secondary terminal of the instrument current transformer is calculated through each measured current value of the secondary terminal of the instrument current transformer for the three-phase power input from the secondary terminal current measurement unit, and the calculated The current imbalance value is higher than the reference open-circuit current imbalance value, and the measured voltage value of the secondary terminal of the instrument current transformer for at least one phase of the three-phase power supply is higher than the reference open-circuit voltage value, and the measured voltage value of the secondary terminal of the instrument current transformer is higher than the reference open-circuit voltage value. If the measured current value is lower than the reference open current value, output a secondary terminal open signal to the outside;
When the secondary terminal opening signal is output to the outside, if a reset command is not received from the user through the reset button during the input blocking delay time, blocking the circuit breaker is operated; Characterized by

It further includes a warning sound unit that receives a warning sound signal from the control unit and generates a warning sound to the outside,

The control unit,
Through the user input unit, a predetermined standard warning poor contact voltage value, standard open contact defective voltage value, standard contact defective current value, and standard contact defective zero phase current (Zero-Phase Electric) of each of the secondary terminals of the instrument current transformer for the three-phase power supply are input. Current) value, a predetermined range of the standard contact defect phase difference value, and the standard contact defect current imbalance value are input;
The measured voltage value of the secondary terminal of the instrument current transformer for at least one phase of the three-phase power supply is higher than the standard warning poor contact voltage value, and the measured current value of the secondary terminal of the instrument current transformer is higher than the reference poor contact current value. ,
The zero-phase current value for the secondary terminal of the instrument current transformer is calculated through each measured current value of the secondary terminal of the instrument current transformer for the three-phase power input from the secondary terminal current measurement unit, and the calculated If the zero-phase current value is lower than the reference poor-contact zero-phase current value and the calculated current imbalance value is lower than the reference poor-contact current imbalance value, or the secondary terminal of the instrument transformer for one phase of the three-phase power supply When the difference between the voltage phase value and the current phase value of the secondary terminal of the instrument current transformer is smaller than the predetermined range of the reference poor contact phase difference value, outputting a warning sound signal to the outside;

The control unit,
After outputting the warning sound signal to the outside, if the measured voltage value of each secondary terminal of the instrument current transformer for the three-phase power source is higher than the reference open contact failure voltage value, outputting the secondary terminal open signal to the outside. Thing; A monitoring system applicable to secondary open installation of instrument current transformers.
delete According to paragraph 1,
The control unit,
When the secondary terminal open signal is output to the outside and the circuit breaker is operated to block because a reset command is not received from the user through the reset button during the input blocking delay time, A monitoring system applicable to secondary open installation of an instrument current transformer, characterized in that the blocking operation of the circuit breaker is released only when a reset command is input.