KR0167206B1 - Overcurrent protection control device of electronic type circuit breaker - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overcurrent cutoff control device for an electronic circuit breaker. In the related art, the secondary side of the current transformer is changed from a burden resistor to a voltage signal, and one of the voltage signal sources of each phase is selected in a predetermined order by the signal selector. There is a problem in that the circuit configuration is complicated by configuring the selection signal to determine whether it trips through processing such as differential amplification and digital conversion. In order to solve this conventional problem, the present invention is configured to input the voltage signal of each phase to the differential amplification means and the instantaneous detection means, respectively, to detect the current flowing in one or more phases, calculate the detected signal, According to the present invention, a trip signal according to time characteristic is output by judging an overcurrent condition. The present invention measures a load flowing in a line and prevents a short-circuit and an overcurrent condition in advance when a load flowing over a line is exceeded. Of course, the overheating of the track can be prevented.

Description

Overcurrent cutoff control device of electronic circuit breaker

1 is a block diagram of a conventional overcurrent cutoff control device.

2 is a block diagram showing an embodiment of the present invention.

3 is a block diagram showing another embodiment of the present invention.

4 is a signal flow diagram in accordance with the present invention.

* Explanation of symbols for main parts of the drawings

111,211: current detector 112,212: burden circuit

113: signal converter 114,213: differential amplifier

115,214: microprocessor 116,215: adjustable part

117,216 Temporary adjustment selector 118,217 Alarm display

119,218: constant voltage unit 120,219: instantaneous detection unit

121,220: trip driver 122,221: trip circuit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic circuit breaker, and more particularly, to an overcurrent breaking control apparatus of an electronic circuit breaker, which is suitable for circuit breaker protection by detecting an overcurrent using a current transformer to provide a trip output for a time characteristic.

FIG. 1 is a block diagram of a conventional apparatus, and as shown therein, a load current flowing in each phase of power lines 1a, 1b, and 1c is detected by current transformers 5a, 5b, and 5c, and the detected current is detected by a bridge diode ( By full-wave rectification at 6a, 6b, 6c, the reverse current wave of the bridge diodes 6a, 6b, 6c is output to the power supply unit 10 as a voltage source, and the bridge diodes (9a, 9b, 9c) are provided at the load circuits A current detector 11 for inputting each of the normal waveforms of 6a, 6b, and c6 to a voltage signal source and an analog voltage signal Va, Vb, Vc of each phase which is the output of the current detector 11; An amplified analog voltage signal corresponding to the load current value of each phase by obtaining a difference between a signal selector 14 for arbitrarily selecting one of the signals, and a difference between an output of the signal selector 14 and a predetermined reference voltage of the power supply unit 10; Digital conversion of the differential amplifier 15 and the output of the differential amplifier 15 The analog / digital converter 16 and the output of the analog / digital converter 16 are used as inputs to calculate the average value or the effective value of the load current of each phase, and drive the SR18 according to the calculation result. The signal processing unit 17 which executes the trip operation of the trip device 19 and the outputs of the breaking diodes 12a to 12c connected to the burden circuits 9a, 9b and 9c are input through the zener diode ZD1. In this case, the instantaneous voltage is detected so that the time limit control unit 20 drives the SR 18.

Referring to the operation of the conventional circuit as follows.

First, the current detector 11 detects load currents flowing through the plurality of AC lines 1a, 1b, and 1c at the current transformers 5a, 5b, and 5c, respectively, and performs full-wave rectification at the bridge diodes 6a, 6b, and 6c. An analog voltage signal of each phase, which is a voltage level corresponding to the load current value of each phase, is output.

At this time, the current detector 11 outputs the reverse current wave of the full wave rectification waveforms of the bridge diodes 6a, 6b, 6c to the power supply unit 10 for use as a voltage source, and the normal waveform is burdened for use as a voltage signal source. The circuits 9a, 9b and 9c are connected in parallel to input the voltage signal sources Va, Vb and Vc to the signal selector 14.

The outputs Va, Vb, and Vc of the current detector 11 are inputted to the trip device 19 through the blocking diodes 12a, 12b, and 12c having common output terminals connected thereto, and to the zener diode ZD1. The applied instantaneous voltage is input to the time controller 20.

Accordingly, the signal selector 14 to which the output terminals Sa, Sb, Sc, and Sd of the signal processor 17 are directly connected is one of the voltage signal sources Va, Vb, and Vc input from the current detector 11. One is selected in a predetermined order and input to the differential amplifier 15.

At this time, the differential amplifier 15 inputs the output of the signal selector 14 and the predetermined reference voltage from the power supply 10 to calculate the difference between the two input terminals as an analog voltage signal corresponding to the load current value of each phase. The analog voltage signal is amplified by a predetermined level and output to the analog / digital converter 16.

Therefore, when the analog / digital converter 16 digitally converts the output signal of the differential amplifier 15, the signal processor 17, which is a microprocessor, uses the digital signal as an input and the average value and the effective value of the loads 4b and 4c. After a certain time elapses, the SCR (18) is driven based on the result of the calculation to cause the trip device 19 to turn off the circuit breakers 2a, 2b, and 2c so that an accident due to a short circuit of the load occurs. Will be prevented.

In addition, when the time controller 20 checks the voltage applied through the zener diode ZD1 and determines the overcurrent state, the time control unit 20 drives the breaker 2a, 2b, and 2c in the trip device 19 by driving the SR18. Off will prevent accidents.

However, conventionally, the secondary side of the current transformer is changed from a burden resistor to a voltage signal, and one of the voltage signal sources of each phase is selected in a predetermined order by the signal selector, and the selected signal is processed through a process such as differential amplification and digital conversion. There is a problem that the configuration of the circuit is complicated by configuring to determine whether or not the trip.

The present invention is configured to input the voltage signal of each phase into the differential amplifying means and the instantaneous detecting means, instead of the conventional signal selecting means, in order to solve the conventional problems, thereby detecting the current flowing in the singular or plural phases and detecting the detected signal. By calculating the overcurrent condition according to the calculation result and providing the trip signal according to the time characteristic, it prevents the accident due to the overload condition in advance, and provides the instantaneous and short time characteristic in case of short circuit of the load, so that the power can be cut off quickly. It is an object of the present invention to provide an overcurrent blocking control device for an electronic circuit breaker.

2 is a configuration diagram of an embodiment of the present invention, as shown in the figure, the current of the load supplied with the three-phase power is detected by the current transformers CT1, CT2, CT3 and the detected current is detected by the bridge diodes BR1, BR2, The current detector 111 outputs normal and reverse phase currents by full-wave rectification in BR3, and the constant voltage section outputs voltages Vcc1 and Vcc2 of a predetermined level by inputting the normal current of the current detector 111 as input. 119, a burden circuit 112 for converting the reverse phase current of the current detector 111 into a voltage, and a signal converter for converting the reverse phase voltage converted by the burden circuit 112 into voltage of a normal waveform ( 113, a differential amplifier 114 for amplifying the output of the signal converter 113 with a constant gain, a provision adjusting unit 116 for setting a function of circuit interruption, and a setting function of the provision adjusting unit 116 A provisional adjustment selection unit 117 for selectively reading the data at regular intervals, and the difference After digitally converting the output of the amplifying unit 114, the maximum phase is determined with respect to the setting function of the provisional adjustment selecting unit 117, and the effective value for the maximum phase is calculated to detect the overcurrent, and outputs a time signal when the overcurrent is detected. The processor 115, the alarm display unit 118 for displaying an alarm by the overcurrent state display signal of the microprocessor 115, and the output of the signal converter 113 are logically summed, and the logic sum signal is the constant voltage unit. When the output voltage Vcc1 of 119 is greater than the divided reference voltage, the instantaneous detector 120 outputs the trip signal, and the trip signal of the instantaneous detector 120 and the time signal of the microprocessor 115. It consists of the trip drive part 121 which drives the trip circuit 122 by this.

The burden circuit 112 includes ground resistors R1, R2, and R3 connected to the R, S, and T phase outputs of the current detector 111, respectively.

The signal converter 113 includes amplifiers OP1, OP2, and OP3 for inverting and amplifying the R, S, and T phase voltages of the burden circuit 112, respectively.

The differential amplifier 114 includes amplifiers OP4, OP5, and OP6 that amplify each output voltage of the signal converter 113 with a constant gain.

The alarm display unit 118 includes a transistor Q2 that is turned on and off by an alarm signal of the microprocessor 115, and an LED (LED) that emits light to indicate an overcurrent state when the transistor Q2 is turned on. .

The trip driver 121 applies the output Vcc2 of the constant voltage unit 119 to the collector of the transistor Q1 to which the time signal of the microprocessor 115 is applied to the gate, and the emitter of the transistor Q1 is connected. The cathode of the diode D4 to which the cathode of the diode D5 and the output of the instantaneous detector 120 are connected to the ground resistor R22 so that the connection point is connected to the trip circuit 122 through the resistor R23. Configure.

The instantaneous detection unit 190 is the maximum when the sum of the diodes D1 (D2) and D3 for summing the outputs of the signal converters 113 and the diodes D1 to D3 becomes a predetermined level or more. Zener diode ZD1 in the reverse direction that maintains the instantaneous voltage and comparator COMP1 that outputs the trap signal high when the output of the zener diode ZD1 is greater than the output Vcc1 of the constant voltage unit 119. .

Reference numerals R4 to R21, R24 and R25 in the drawings are resistors.

Referring to the operation and effect of the present invention configured in this way in detail as follows.

First, the current detector 111 to which the three-phase power sources R, S, and T are applied is full-wave rectified by the bridge diodes BR1 to BR3 when the current transformers CT1 to CT3 detect a predetermined current. The current of the reverse phase waveform is input to the unit 119 and is input to the signal converter 113 through the burden circuit 112.

The burden circuit 112 converts the output of each of the current detectors 111 into voltages by the ground resistors R1 to R3.

At this time, the signal conversion unit 113 inverts and amplifies the voltage of each phase converted through the burden circuit 112 in the amplifiers OP1 to OP3 to convert the signal of the reverse phase waveform into a signal of the normal waveform and the instantaneous detection unit 120. ) And the differential amplifier 114.

Accordingly, when the differential amplifier 114 non-inverts amplifies each output of the signal converter 113 with a constant gain in the amplifiers OP4 to OP6, the microprocessor 115 may determine each of the differential amplifiers 114. Digital output is converted into internal memory.

Here, the gains of the amplifiers OP4 to OP6 are determined by the resistors R15 and R16 (R17 and R18) and R19 and R20, respectively.

In addition, when a user arbitrarily sets a circuit interruption function such as rated current, short time current, short time, instantaneous current, instantaneous time, and the like, the temporary adjusting selector 117 is provided to the temporary adjusting part 116. The set function is selectively read at regular intervals and input to the microprocessor 115.

At this time, the microprocessor 115 samples the voltage input from the differential amplifier 114 at regular intervals to determine the maximum phase of the three-phase voltage, accumulates the sampling value, and obtains an effective value for the maximum phase. When it is determined that the overcurrent is compared with the reference value, the time limit signal that is high is output to the trip driver 121.

In addition, the instantaneous detector 120 may add the outputs of the signal converters 113 at the OR gates of the diodes D1 to D3 to determine a range of peak values for the instantaneous maximum phase through the zener diode ZD1. The comparator is input to the non-inverting terminal of the comparator COMP1 and the output voltage Vcc1 of the constant voltage unit 119 is divided by the resistors R13 and R14 and input to the inverting terminal of the comparator COMP1 at a predetermined reference voltage. When the input voltage of the non-inverting terminal becomes greater than the reference voltage of the inverting input terminal, COMP1 outputs a trip signal that is high to the trip driver 121.

The Zener diode ZD1 performs an operation to operate unconditionally instantaneously when the logic summed at the diodes D1 to D3 is greater than or equal to the reference voltage level, and is used for terminal protection of the comparator COMP1.

Therefore, when the trip signal is input high by the instantaneous detector 120, the trip driver 121 sequentially inputs the diode D14 and the resistor R23 to the trip circuit 122 through the sequence signal and the time signal from the microprocessor 115. Is input high, the transistor Q1 is turned on to input the output Vcc2 of the constant voltage unit 119 to the trip circuit 122 through the transistor Q1, the diode D3, and the resistor R23 sequentially. By performing a trip operation, the system is protected from overpower.

In addition, when the microprocessor 115 calculates the output of the differential amplifier 114 and detects an overcurrent, when the microprocessor 115 outputs the alarm display signal high, the alarm display unit 118 turns on the transistor Q2 to turn on the LED. By emitting light, detection of overcurrent is indicated.

The above operation will be described with reference to FIG. 4.

First, when the constant voltage unit 119 outputs a voltage Vcc1 of a predetermined level by inputting the current of the normal waveform rectified by the current detector 111, the microprocessor 115 performs an initialization operation and then adjusts the selection unit. Read the provisional adjustment setting data set by the user from 117.

In the above, the microprocessor 115 reads the provisional adjustment setting data every predetermined period (for example, 0.1 sec) to check whether the user has changed the setting.

Thereafter, the microprocessor 115 checks the value of the phase counter PC in order to determine the phase to be read. The microprocessor 115 performs the R phase when the value of the phase counter PC is 1; , If 2, it is recognized as S phase, and if 3, T phase.

At this time, when the value of the phase counter (pc) is recognized as the determination of the R phase as 1, the microprocessor 115 increases the value of the phase counter (PC) by 1 and selects the sampling counter (SC) by 1 to select the next phase. After increasing, the internal commercially available analog / digital conversion circuit is enabled.

Accordingly, the microprocessor 115 digitally converts the output of the amplifier OP4 of the differential amplifier 114, stores the value in the address buffer ADR ′, corrects the offset data, and compares the data with the actual read data. Whether the instantaneous value is determined by using the difference value as actual data ADR.

Here, the value of the address buffer ADR is sampling data at any moment.

Therefore, when the microprocessor 115 determines the instantaneous time, the microprocessor 115 outputs a time limit signal that is high to the trip driver 121 to immediately perform a trip.

If it is not instantaneous, the microprocessor 115 squares the value of the address buffer ADR and stores it in the sampling accumulation data buffer R-ADD and checks the sampling counter SC on R for more than a predetermined period N. If the result is confirmed over a certain period (SC = N), the accumulated data (R-ADD) up to now is stored in the final cumulative data buffer (R-SUM) and the value of the phase counter (PC) is determined. You will be judged.

Also, in the case of the S phase, the same operation as described above is performed.

However, in the case of the T phase, when the sampling counter SC is at a predetermined period N, the operation of storing the accumulated data T-ADD up to the present in the final cumulative data buffer T-SUM is the same as that of the R phase. Thereafter, the sampling counter SC is initialized to zero, and it is determined whether the current time t has elapsed a predetermined time (0.1 sec).

At this time, the microprocessor 115 reads the provisional adjustment setting data of the provisional adjustment selection unit 117 when the current time t has elapsed a predetermined time (0.1 sec), checks whether the setting data has been changed, and then checks the phase counter (PC). ), And compare the sampling cumulative data (R-SUM, S-SUM, T-SUM) on R, S, and T if the current time (t) has not passed a predetermined time (0.1 sec). Large cumulative data is determined.

Accordingly, the microprocessor 115 stores the data found to be the maximum phase in the buffer (i-MAX) to obtain an effective value, and determines whether the current current is in the overcurrent range based on the effective value. In the case of checking the value of the phase count (PC), and if it is determined that the over-current state, the internal timer is operated to perform a time limit operation, and when a predetermined operation time has elapsed, a trip signal that is a high pulse is output to the trip driver 121. Have a trip performed.

Meanwhile, another embodiment of the present invention is configured as shown in FIG. 3 by removing the signal converter 113 for converting the voltage of the burden circuit 112 to a normal waveform in one embodiment.

That is, when the reverse phase output current output from the current detector 211 is converted into a voltage by the burden circuit 212, the differential amplifier 213 amplifies the amplifiers OP11 to OP13 with a predetermined gain, respectively, to the microprocessor 214. Will be entered.

Accordingly, the microprocessor 214 determines whether there is an overcurrent by the same signal flow as that of FIG. 4, and when the overcurrent is detected, the microprocessor 214 outputs a time limit signal, which is a trigger pulse, to the trip driver 220.

As described in detail above, the present invention measures the load flowing on the line and prevents short circuit and overcurrent conditions in advance when the load exceeds the predetermined range, thereby protecting the load side device and preventing overheating of the line. .

Claims (5)

Current detection means for outputting normal and reverse phase currents by detecting the current of the load supplied with the three-phase power supply in the current transformers CT1, CT2 and CT3 and full-wave rectifying the detected current, and the reverse phase current of the current detection means. A burden circuit for converting to voltage, differential amplification means for amplifying the output of the burden circuit with a constant gain, provisional adjustment means for setting each function of circuit interruption, and setting function of the provisional adjustment means for a predetermined period selectively When digital output is converted between the adjustable adjustment selecting means to be read out and the output of the differential amplifying means, the maximum phase is determined for the setting function of the adjustable adjustment selecting means, and the effective value for the maximum phase is calculated to detect the overcurrent. Control means for outputting a signal, alarm display means for displaying an alarm by an overcurrent state display signal of the control means, and outputting of the signal conversion means Is an instantaneous detection means for outputting a trip signal when the logic sum signal is greater than a reference voltage of a predetermined level, and a trip driving means for performing a trip by a trip signal of the instantaneous detection means or a time signal of the control means. An over-current interruption control device of an electronic circuit breaker, characterized in that the configuration. 2. The overcurrent interruption control device according to claim 1, comprising a signal conversion means for converting the output of the burden circuit into a normal waveform and outputting the signal to the differential amplification means. 3. The overcurrent interruption control device according to claim 2, wherein the signal conversion means comprises amplifiers (OP1, OP2, OP3) for inverting and amplifying the R, S, and T phase voltages of the burden circuit, respectively. 2. The trip driving means according to claim 1, wherein the trip driving means applies a constant voltage Vcc2 to the collector of the transistor Q1 to which the time signal of the control means is applied to the gate and the diode D5 to which the emitter of the transistor Q1 is connected. The circuit of the electronic circuit breaker, characterized in that the cathode of the diode (D4) connected to the output of the cathode and the instantaneous detection unit 120 is connected to the ground resistor (R22) so that the connection point is connected to the trip circuit through the resistor (R23). Overcurrent cutoff control device. 2. The instantaneous detection means according to claim 1, wherein the instantaneous detection means comprises: an OR gate for summing the voltages according to each phase current detection; and a reverse Zener diode ZD1 for maintaining the maximum instantaneous voltage when the output of the OR gate becomes above a predetermined level; And a comparator (COMP1) for outputting a trap signal high when the output of the zener diode (ZD1) is greater than the constant voltage (Vcc1).