JP4172634B2 - 3-phase 3-wire circuit breaker with phase loss protection - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a circuit breaker with a three-phase three-wire type open phase protection that detects a phase loss of a three-phase three-wire type circuit and interrupts the circuit.
[0002]
[Prior art]
Conventional circuit breakers with three-phase, three-wire open-phase protection have each phase R, S, T conductor of the three-phase, three-wire circuit passed through the zero-phase current transformer to output the zero-phase current transformer. An amplifier is connected, and an electromagnetic device is connected to the amplifier. In addition, a current transformer is provided for each primary phase conductor of the zero-phase current transformer, and the secondary winding of these current transformers is connected to an open triangular circuit, and a conductor is output from one open terminal of the open triangular circuit. Is connected to the other open terminal of the open triangle circuit through the zero-phase current transformer, and the earth leakage circuit breaker is tripped when there is a three-phase phase loss using the output current between the open terminals of the open triangle circuit. It has become. (For example, refer to Patent Document 1).
[0003]
[Patent Document 1]
JP 56-74023 A (2nd page, FIG. 1)
[0004]
[Problems to be solved by the invention]
However, the conventional circuit breaker with three-phase, three-wire phase loss protection has a disadvantage that the circuit breaker becomes large because a current transformer having a size capable of penetrating the conductor is provided for each phase. .
[0005]
Accordingly, in view of the above problems, an object of the present invention is to provide a circuit breaker with a three-phase three-wire type open-phase protection that can reduce the size of the circuit breaker.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the integrated circuit detects the open phase of the three-phase three-wire circuit from the power supply line connected to each line of the three-phase three-wire circuit, turns on the trigger circuit by the output of the integrated circuit, and trips In a circuit breaker with a three-phase three-wire open phase protection that drives a coil and opens and closes a switching contact of a three-phase three-wire circuit, a rectifier diode, a light-emitting diode of a photocoupler, and a resistor between each phase of the power line Are connected to each other, a voltage dividing resistor is connected to the power supply line via a full-wave rectifier circuit, and a connection point of the voltage dividing resistor is connected to the integrated circuit and the collector of the photocoupler transistor connected in parallel. When the emitter is connected to the ground line and the 3-phase 3-wire circuit is energized, the light-emitting diode of the photocoupler emits light, the transistor is turned on, and the divided voltage of the voltage dividing resistor is preset in the integrated circuit. Threshold When the three-phase three-wire circuit is lost, the divided voltage of the voltage divider resistor is integrated while the light-emitting diode of the photocoupler connected to the lost phase does not emit light and the transistor is off. The charging circuit is charged by the integrated circuit exceeding the threshold value, and when the charging circuit is charged to the predetermined value, the integrated circuit turns on the trigger circuit and drives the trip coil to open the switching contact. And
[0007]
DETAILED DESCRIPTION OF THE INVENTION
If the three-phase three-wire circuit is not open, when the rectifier diode, photocoupler light-emitting diode, and resistor connected to each phase of the three-phase three-wire circuit through the power line are energized, the integrated circuit terminals Since the input divided voltage of the voltage dividing resistor does not exceed the threshold value of the phase loss judgment criterion set in advance by turning on the photocoupler transistor, the trip coil is not driven and the three-phase three-wire circuit is not cut off. In addition, when one phase of the three-phase three-wire circuit is lost, two of the photocouplers are turned off, and during that time, the divided voltage of the voltage dividing resistor exceeding the threshold is applied to the terminal of the integrated circuit. . At this time, the integrated circuit charges the capacitor, and when the capacitor is charged to a predetermined value, the integrated circuit outputs a trigger signal to turn on the thyristor, the trip coil is excited and the switching contact is opened, and the three-phase three Wired circuit breaks.
[0008]
【Example】
One embodiment of a circuit breaker with a three-phase three-wire phase loss protection according to the present invention will be described with reference to the accompanying drawings of FIGS.
[0009]
The circuit breaker 1 with a three-phase three-wire type open-phase protection has a power line 2 connected to each line of the three-phase three-wire circuit R, S, T, and a rectifier diode D1 connected in series between the phases of the power line 2 And the light-emitting diode of the photocoupler P1, the resistor R1, the rectifier diode D2, the light-emitting diode of the photocoupler P2 and the resistor R2, the rectifier diode D3, the light-emitting diode of the photocoupler P3 and the resistor R3, and the power line 2 The full wave rectifier circuit 3 is connected to the Between the output terminals of the full-wave rectifier circuit 3, a trip coil TC for opening the switching contact 4 of the three-phase three-wire electric circuits R, S, T, and a thyristor as a trigger circuit for driving the trip coil TC The SCRs are connected in series, and the gate of the thyristor SCR is connected to the eighth terminal of the integrated circuit IC having an overvoltage detection function. Further, a step-down resistor R4 is connected to the power supply line 5 connected to the integrated circuit IC from the full-wave rectifier circuit 3 via the trip coil TC, and a smoothing capacitor C1 and a constant voltage are connected between the power supply line 5 and the ground line 6. A diode ZD and voltage dividing resistors R5 and R6 are connected. The connection point 7 of the voltage dividing resistors R5 and R6 is connected to the 11th terminal of the integrated circuit IC and the collectors of the transistors of the photocouplers P1 to P3, and the emitter of the transistor is connected to the ground line 7. A capacitor C2 as a charging circuit is connected between the 10th terminal of the integrated circuit IC and the ground line.
[0010]
When the three-phase three-wire electric circuits R, S, and T are normally energized, that is, when there is no phase loss, the photocouplers P1 to P3 can be seen from the P1 to P3 current waveforms in FIG. The current waveform is energized in order with the phase of the current waveform shifted by 120 °, and one of the light emitting diodes and the transistor is always on. Further, the full-wave rectifier circuit 3, the resistor R4, the smoothing capacitor C1, and the constant voltage diode ZD convert the AC voltage into a DC voltage that is stepped down, and the integrated circuit IC is overvoltaged at the connection point 7 of the voltage dividing resistors R5 and R6. Although a voltage exceeding the threshold value to be detected is generated, a threshold value is applied to the 11th terminal of the integrated circuit IC as shown by the 11th terminal voltage waveform in FIG. No voltage exceeding is applied. Therefore, the integrated circuit IC does not output a trigger signal, and the thyristor SCR is not turned on, so that the trip coil TC is not driven and the three-phase three-wire electric circuits R, S, and T are not cut off.
[0011]
In addition, when one phase of the three-phase three-wire circuit R, S, T is lost, two photocouplers connected to the lost phase as shown by the current waveforms P1 to P3 in FIG. Only one photocoupler is turned on without being turned on. Therefore, since the two transistors are not turned on, the divided voltage of the voltage dividing resistors R5 and R6 exceeding the threshold value is applied to the 11th terminal of the integrated circuit IC while the two transistors are turned off. In response to this, the integrated circuit IC charges the capacitor C2 as shown by the voltage waveform at the 10th terminal in FIG. When the capacitor C2 is charged to a predetermined value, a trigger signal is output from the eighth terminal of the integrated circuit IC to turn on the thyristor SCR as shown in the voltage waveform at the eighth terminal in FIG. Excitation drive is performed to open the switching contact 4 and the three-phase three-wire electric circuits R, S, T are cut off.
[0012]
Even if the energization of the photocouplers P1 to P3 is stopped for some reason, the trip coil TC is not driven unless the capacitor C2 is charged to a predetermined value, so that malfunction can be prevented.
[0013]
Further, in the present invention, as shown in FIG. 3, an integrated circuit IC having a leakage detecting function is used, and by adding a zero-phase current transformer 8, a three-phase three-wire open phase can be easily achieved with a small number of parts. It can be changed to an earth leakage breaker with protection. Reference numeral 9 denotes a leakage test circuit.
[0014]
【The invention's effect】
As described above, the integrated circuit detects the open phase of the three-phase three-wire circuit from the power supply line connected to each line of the three-phase three-wire circuit, and the trigger circuit is turned on by the output of the integrated circuit to drive the trip coil. In a circuit breaker with three-phase three-wire open-phase protection that opens and closes the switching contact of the three-phase three-wire circuit, a rectifier diode, a photocoupler light emitting diode, and a resistor are connected between each phase of the power line. Then, a voltage dividing resistor is connected to the power supply line via a full-wave rectifier circuit, the node of the voltage dividing resistor is connected to the integrated circuit and the collector of the photocoupler transistor connected in parallel, and the emitter of the transistor is grounded When the three-phase three-wire circuit is connected to the line, the light-emitting diode of the photocoupler emits light, the transistor is turned on, and the divided voltage of the voltage dividing resistor has a preset threshold value in the integrated circuit. Not over When the three-phase three-wire circuit is lost, the light-emitting diode of the photocoupler connected to the lost phase does not emit light, and the divided voltage of the voltage dividing resistor is the threshold of the integrated circuit while the transistor is off. The charging circuit is charged by the integrated circuit beyond the limit value, and when the charging circuit is charged to the predetermined value, the integrated circuit turns on the trigger circuit and drives the trip coil to open the switching contact, thereby reducing the size of the circuit breaker. There is an effect that can be made.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of a circuit breaker with a three-phase, three-wire phase loss protection according to the present invention.
2 is a waveform diagram in each part of the circuit of FIG. 1, where (a) is a current waveform of photocouplers P1 to P3, (b) is a voltage waveform at the 11th terminal of the integrated circuit, and (c) is 10 of the integrated circuit. No. terminal voltage waveform, (d) is the No. 8 terminal voltage waveform of the integrated circuit.
FIG. 3 is a modified example of a circuit breaker with a three-phase three-wire phase loss protection according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... 3 phase 3 wire type circuit breaker with phase loss protection 2 ... Power supply line 3 ... Full wave rectifier circuit 4 ... Switching contact 5 ... Power supply line 6 ... Ground line 7 ... Connection point R, S, T ... Three-phase three wire Type electric circuit D1-D3 ... Rectifier diode P1-P3 ... Photocoupler R1-R4 ... Resistor R5, R6 ... Voltage dividing resistor TC ... Trip coil SCR ... Thyristor IC ... Integrated circuit C1, C2 ... Capacitor ZD ... Constant voltage diode

Claims (1)

The open circuit of the three-phase three-wire circuit is detected by an integrated circuit from the power supply line connected to each line of the three-phase three-wire circuit, and the trigger circuit is turned on by the output of the integrated circuit to drive the trip coil, In the circuit breaker with a three-phase three-wire open-phase protection that opens and closes the switching contact of the three-phase three-wire circuit, a rectifier diode, a photocoupler light emitting diode, and a resistor are connected between each phase of the power line. A voltage dividing resistor is connected to the power supply line via a full-wave rectifier circuit, and a connection point of the voltage dividing resistor is connected to the integrated circuit and a collector of the photocoupler transistor connected in parallel. When the three-phase three-wire circuit is energized, the light emitting diode of the photocoupler emits light and the transistor is turned on, and the divided voltage of the voltage dividing resistor is the integrated circuit In When the three-phase three-wire electric circuit is lost, the light-emitting diode of the photocoupler connected to the lost phase does not emit light and the transistor is turned off. When the divided voltage of the voltage dividing resistor exceeds the threshold value of the integrated circuit, the integrated circuit charges the charging circuit, and when the charging circuit is charged to a predetermined value, the integrated circuit turns on the trigger circuit; A circuit breaker with a three-phase, three-wire phase loss protection, wherein the trip coil is driven to open the switching contact.

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