JP6297439B2 - Earth leakage breaker - Google Patents

Description

  The present invention relates to a leakage breaker that detects a leakage current in a main circuit and cuts off an energization current, and more particularly, a leakage current that causes a test operation to be performed by an intermittent current generated from a pulsating current of a half-wave rectifier as a drive power source of the leakage breaker. Regarding circuit breakers.

A conventional earth leakage circuit breaker will be described with reference to FIG.
In FIG. 4, 1, 1 and 1 are main circuit conductors for supplying a three-phase load current, 2 is a switching contact for turning on / off the main circuit, and 3 is a zero-phase current transformer (Zero phase) for detecting leakage. Current Transformer (hereinafter referred to as ZCT), 4 is a constant voltage circuit, 5 is a thyristor that performs a switching operation when leakage is detected in the main circuit, 6 is a tripping unit that opens the contact for switching, and 7 is a rectifier circuit , 8 are constant voltage circuits, and 11 is a test switch.

  In the conventional earth leakage breaker 100 having such a configuration, when an abnormal earth leakage occurs in the main circuit conductors 1, 1, 1, the earth leakage is detected by the zero-phase current transformer (ZCT) 3, and the secondary winding 3a. Current flows through When a current exceeding a predetermined level flows through the secondary winding 3a, the leakage detection circuit 4 causes the current to flow to the gate side of the thyristor (SCR) 5 to operate the SCR 5, and the trip circuit 6 (details are omitted) ) Is operated to trip the switching contact portion 2.

Here, the operation of the earth leakage circuit breaker during the test operation in the conventional example shown in FIG. 4 will be described.
When the test switch 11 is turned on, a current flows through the test switch winding 3b, and an output signal is generated on the secondary winding 3a side of ZCT3. When the ZCT output signal is generated, the leakage detection circuit 4 determines that the leakage has occurred when the magnitude of the signal exceeds a predetermined level. The detection at the predetermined level may measure the rising or falling state of the detection signal. For example, when a 50 Hz power source is used, the first rising signal is detected, and the second rising signal is detected within 18 to 22 msec from the detection of the first rising signal, that is, within 10% of the power cycle. If a signal is detected, it is determined that there is a leak. In this case, it is possible to determine a leakage by detecting the rising signal twice. In addition, it becomes difficult to detect noise as leakage, and the leakage state can be detected more reliably. Detection of rising and falling may be combined, and detection may be performed a plurality of times. If the number of times of detection is increased, it takes time to determine that there is a leakage, but it is less likely to be erroneously determined to be a leakage due to noise.
When the leakage detection circuit 4 determines that leakage has occurred, the leakage detection circuit 4 applies a voltage to the gate of the SCR 5 to turn it on, and operates the SCR 5. As a result, by passing a current through the tripping portion 6, the switching contact portion 2 is forcibly opened to interrupt the leakage.

  It is another object of the present invention to provide a circuit breaker capable of reducing the voltage applied between the contact points of the test switch and reducing the insulation resistance between the test winding and the secondary winding of the zero-phase current transformer. There exists Unexamined-Japanese-Patent No. 2009-089574 (patent document 1). This is to obtain an earth leakage circuit breaker that can reduce the voltage applied between the contact points of the test switch and reduce the dielectric strength between the test winding and the secondary winding of the zero-phase current transformer. As a problem, a zero-phase current transformer inserted in an AC circuit, a leakage detection circuit that generates an output when a leakage current flowing through the zero-phase current transformer exceeds a predetermined level, and an output of the leakage detection circuit A tripping circuit that opens the breaker inserted in the AC circuit, a rectifying circuit that rectifies the voltage of the AC circuit and supplies it to the leakage detection circuit, and a test wound around the zero-phase current transformer An earth leakage circuit breaker having a test circuit for causing a pseudo-leakage current to flow in the winding, wherein the test circuit is connected in series to the output side of the rectifier circuit, the test winding, the test switch, the limiting resistor, and the optical insulating means. Consists of connected bodies It is.

  This test circuit includes a full-wave rectifier directly connected to the main circuit and an optical isolation means (light emitting element) as a power source. On the output side of the rectifier circuit, a test winding, a test switch, a limiting resistor, and an optical isolation means ( It is characterized by comprising a serial connection body with a light receiving element).

JP 2009-89574 A

  The conventional earth leakage circuit breaker has a problem that the test circuit becomes a high voltage because an alternating current from the main circuit flows through the test circuit. For this reason, the test circuit is required to have an insulation design that can withstand this, and requires a separation distance from other circuits, thereby pressing down the space of the earth leakage breaker and preventing the miniaturization. In addition, since the generation of a leakage test signal needs to generate a signal similar to an AC power supply, the generation method is not easy. For this reason, generation of a test signal for detecting leakage is a big problem in a limited apparatus configuration.

  As for test switches, small switches that can be used with the main circuit voltage are not commercially available, and it is necessary to manufacture them using leaf springs in-house, but this may cause problems with contact reliability. .

  In Patent Document 1, an earth leakage circuit breaker that can reduce the voltage applied between the contacts of the test switch and reduce the insulation resistance between the test winding and the secondary winding of the zero-phase current transformer. Although it is similar in that a photocoupler is used, the primary side (light emitting unit) of the photocoupler is connected to the AC side of the main circuit. In Patent Document 1, a full-wave rectifier circuit is used as the rectifier circuit.

  Therefore, in Patent Document 1, although the effect that the insulation resistance between the test winding and the secondary winding of the zero-phase current transformer can be lowered is known, the light-emitting element of the optical insulating means is still main. The circuit is inserted between the AC circuit of the circuit and the full-wave rectifier circuit, and it is necessary to provide a large resistor on the miniaturized substrate, which leaves a problem for miniaturization.

  In the earth leakage breaker of the present invention, a half-wave rectifier circuit is used as a power source for the earth leakage detection circuit, and the output of the constant voltage circuit is detected from the pulsating current of the half-wave rectifier circuit via the half-wave rectification signal detection means. When the intermittent current is generated on the side and the test switch of the test circuit is turned on, the leakage breaker test operation is performed by the generated intermittent current.

  In the earth leakage circuit breaker for interrupting the AC power supply according to the present invention, the AC power supply includes a zero-phase current transformation means in which a primary winding and a secondary winding are wound, and a half-wave that rectifies the AC power supply in half-waves. The AC power source connected to the rectifying means and half-wave rectified is connected to the pseudo-leakage current signal generating means for generating a pseudo-leakage current signal that is a pseudo-leakage current, and the generated pseudo-leakage current signal The receiving means that receives the current supplies the current corresponding to the received pseudo-leakage current signal to the primary winding in a predetermined case, and the pseudo-leakage current that has flowed to the secondary winding by the current corresponding to the supplied signal. The leakage detecting means for detecting outputs a signal for cutting off the AC power supply when it is detected that the leakage current is present, and the circuit breaking means cuts off the AC power supply by the signal for cutting off.

  According to the present invention, it is possible to easily generate a cutoff signal by using a half-wave rectifier circuit.

The circuit block diagram which shows the 1st Example of the earth-leakage circuit breaker of this invention The circuit block diagram which shows the 2nd Example of the earth-leakage circuit breaker of this invention Time chart of first embodiment of earth leakage circuit breaker of the present invention Circuit diagram showing a conventional earth leakage breaker

  The earth leakage breaker of the present invention uses a half-wave rectifier circuit as a power source for the earth leakage detection circuit, and a test switch using an intermittent current generated on the output side of the constant voltage circuit from the input pulsating flow through the half-wave rectification signal detection means. It is configured to perform the operation.

  Further, the leakage breaker of the present invention is connected to a main circuit conductor of the leakage detection circuit with a half-wave rectification circuit, and the half-wave rectification circuit is used as a power supply for the leakage detection circuit and is rectified by the half-wave rectification circuit. The current flows to the primary side of the half-wave rectification signal detection means, the current flows to the zero-phase current transformer, and the test is performed with the intermittent current generated on the output side of the constant voltage circuit via the half-wave rectification signal detection means. It is configured to perform a switch operation.

  Further, the half-wave rectified signal detecting means of the leakage breaker of the present invention is an optical insulating means such as a photocoupler.

  The leakage breaker of the present invention creates a low-current intermittent current that simulates the alternating current of the leakage current when the test switch is operated by the half-wave rectifier circuit connected to the main circuit conductor of the leakage detection circuit. The optical insulation means such as a photocoupler is blinked by the current of the rectifier circuit to obtain an intermittent current that simulates a leakage current, and thus the zero-phase current transformer is operated.

  Furthermore, in the earth leakage breaker of the present invention, a current limiting circuit configured as an active element is connected as a test circuit so as to control the magnitude and switching of the test current.

  Embodiments of the earth leakage breaker of the present invention will be described below with reference to FIGS. FIG. 1 is a circuit configuration diagram of the first embodiment in the case where the power source of the leakage detection circuit is a single-phase current.

In FIG. 1, 1, 1 and 1 are main circuit conductors through which a load current is passed, 2 is a switching contact for turning on and off the main circuit, 3 is a zero-phase current transformer (ZCT) for detecting leakage, and 4 A leakage detection circuit, 5 is a thyristor that performs a switching operation when leakage is detected in the main circuit, 6 is a tripping part ( specifically a tripping coil) that opens the switching contact part, 7 is a half-wave rectification circuit, 8 is a constant voltage circuit, 9 is a photocoupler (light emitting side 9a, light receiving side 9b), 10 is a switching circuit or switching element, 11 is a test switch, and 12 and 13 are zener diodes. Note that the test switch and the switching circuit or the switching element 10 are collectively configured as a single device as a device configuration, but in consideration of electrical connection, the test switch is directly connected to the secondary side 9b of the photocoupler. That is not desirable. In this case, the number of parts can be reduced, and the apparatus configuration can be simplified.

  Here, a half-wave rectified voltage is supplied to the light emission side (primary side) 9 a of the constant voltage circuit 8 and the photocoupler 9 via the half-wave rectifier circuit 7. Since the first embodiment is a case where the power source of the leakage detection circuit is a single-phase current, the half-wave rectifier circuit 7 is one of the main circuits 1, 1, 1 of the R phase, T phase, and S phase. And functions as a power source for operating a subsequent amplification IC or the like.

Here, the operation of the leakage breaker in the first embodiment of the present invention shown in FIG. 1 will be described.
When the balance of the currents flowing in the R phase, T phase, and S phase of the main circuit conductors 1, 1, 1 is lost, it is detected by the ZCT 3, whereby the ZCT 3 passes a current through the secondary winding 3a as indicated by an arrow a. . The direction of the current arrow may be any.
Then, this current is detected by the leakage detection circuit 4, and the leakage detection circuit 4 applies a voltage to the gate of the thyristor (SCR) 5 to turn it on to operate the SCR 5. As a result, by passing a current through the tripping portion 6, the switching contact portion 2 is forcibly opened to interrupt the leakage.

Next, the operation of the earth leakage circuit breaker during the test operation in the first embodiment of the present invention shown in FIG. 1 will be described.
First, when the test switch 11 is in the OFF state, the current indicated by the arrow b does not flow through the photocoupler light receiving side (secondary side) 9b.
Here, when the test switch 11 is turned on, a current flows through the secondary side 9b of the photocoupler, the Tr10 as a switching circuit operates, and a current flows through the test switch winding 3b.
Here, the test switch is described as a single switch (tactile switch) that performs physical contact. In addition, when not only a single switch (tactile switch) but also a semiconductor switch or a membrane switch, it is resistant to dust and has high durability.
Further, the switch may be determined to be in the ON state by receiving a signal from a device (not shown) different from the earth leakage breaker as well as the test switch mounted on the earth leakage breaker. In this case, it is possible to perform the interruption operation by the earth leakage interruption test from the different device without the user directly operating the switch.
Moreover, it becomes feasible not only to test but also to shut off the device connected to the secondary side of the earth leakage breaker from the primary side by remote control.
In the other embodiments, the other configuration described above for the switching element can be similarly used, and in this case, the effect of the used element is obtained.
When a current (ZCT winding current (D) in FIG. 3) flows through the test switch winding 3b, an output signal (ZCT output signal (E) in FIG. 3) is generated on the secondary winding 3a side of ZCT3. .
When this ZCT output signal (E) is generated, the leakage detection circuit 4 detects the rise of the signal, and in this case, determines that leakage has occurred. In this case, in order to prevent malfunction, it may be determined that there is a leakage when the second rising or the like is detected, or it may be determined that there is a leakage when a predetermined number of rising edges are detected at regular intervals. good.
When the leakage detection circuit 4 determines that leakage has occurred, the leakage detection circuit 4 applies a voltage to the gate of the thyristor (SCR) 5 to turn it on to operate the SCR 5. As a result, by passing a current through the tripping portion 6, the switching contact portion 2 is forcibly opened to interrupt the leakage.

In the embodiment of the present invention, the photocoupler has been described as a specific embodiment as the means for transmitting and receiving the detected half-wave rectified signal. However, the means capable of detecting the half-wave rectified signal (half-wave rectified signal detecting means). If so, for example, it is also possible to transmit and receive by signals such as sound waves, ultrasonic waves, visible light, infrared rays (infrared light), and the like. In order to insulate the primary side and the secondary side, it is desirable to be an element or module that can transmit and receive signals without electrical connection. The present invention will be described using a photocoupler that is resistant to size and noise.
The half-wave rectifier circuit is also realized by a diode as a specific embodiment, but is not limited to the diode, and any configuration that can realize a half-wave rectifier circuit may be used.

  The test circuit according to the first embodiment is connected to a current limiting circuit composed of active elements so that the magnitude and open / close of the test current can be controlled. This current limiting circuit is constituted by a combination of an active element and three resistors R 3, R 4, R 5, and the active element is constituted by a transistor 10. The resistors R3 and R4 are connected in series with the test switch 11, and the base of the active element transistor 10 is connected between the resistors R3 and R4. As described above, in the switching circuit 10 including the current limiting circuit composed of active elements (transistors), the current flowing through the switching circuit 10 is appropriately set by appropriately selecting the resistance values of the resistors R3, R4, and R5. It is possible. That is, the magnitude and open / close of the test current can be controlled by the voltage dividing ratio of the resistors R3, R4, R5.

  Next, a second embodiment of the present invention will be described. FIG. 2 is a circuit configuration diagram of the second embodiment when the power source of the leakage detection circuit is a three-phase current. In addition, the structure of the same function as Example 1 attaches | subjects and demonstrates the same code | symbol, and there exists the part which simplified description.

In FIG. 2, 1, 1, 1 are main circuit conductors for supplying a load current, 2 is a switching contact for turning on / off the main circuit, 3 is a ZCT for detecting leakage, 4 is a leakage detection circuit, and 5 is a main detection circuit Thyristor that performs a switching operation when leakage is detected in the circuit, 6 is a tripping part that opens the switching contact part, 7 is a half-wave rectifier circuit, 8 is a constant voltage circuit, 9 is a photocoupler (light emitting side 9a, light receiving) Side 9b), 10 is a switching circuit, 11 is a test switch, and 12 and 13 are zener diodes.

  Here, a half-wave rectified voltage is supplied to the light emission side (primary side) 9 a of the constant voltage circuit 8 and the photocoupler 9 via the half-wave rectifier circuit 7. Since the power source of the leakage detection circuit is a three-phase current in the second embodiment, the half-wave rectifier circuit 7 is a diode connected to each of the R phase, T phase, and S phase of the main circuits 1, 1, 1. And functions as a power source for operating a subsequent amplification IC or the like.

Here, the operation of the earth leakage breaker in the second embodiment of the present invention shown in FIG. 2 will be described.
When the balance of the currents flowing in the R phase, T phase, and S phase of the main circuit conductors 1, 1, 1 is lost, it is detected by the ZCT 3, whereby the ZCT 3 passes a current through the secondary winding 3a as indicated by an arrow a. . Then, this current is detected by the leakage detection circuit 4, and the leakage detection circuit 4 applies a voltage to the gate of the SCR 5 to turn it on to operate the SCR 5. As a result, by passing a current through the tripping portion 6, the switching contact portion 2 is forcibly opened to interrupt the leakage.

Next, the operation of the earth leakage circuit breaker during the test operation in the first embodiment of the present invention shown in FIG. 1 will be described.
First, when the test switch 11 is in the OFF state, the current indicated by the arrow b does not flow through the photocoupler light receiving side (secondary side) 9b. Here, when the test switch 11 is turned on, a current flows through the photocoupler secondary side 9b, the switching circuit Tr10 operates, and a current flows through the test switch winding 3b.

When a current (ZCT winding current in FIG. 4) flows through the test switch winding 3b, an output signal (ZCT output signal in FIG. 4) is generated on the secondary winding 3a side of ZCT3. When this ZCT output signal is generated, the leakage detection circuit 4 determines that leakage has occurred when the magnitude of the signal exceeds a predetermined level (value).
When the leakage detection circuit 4 determines that leakage has occurred, the leakage detection circuit 4 applies a voltage to the gate of the thyristor (SCR) 5 to turn it on to operate the SCR 5. As a result, by passing a current through the tripping portion 6, the switching contact portion 2 is forcibly opened to interrupt the leakage.
Here, also in the second embodiment, the current limiting circuit constituted by the active elements is the same, and the description thereof is omitted.

Next, the operation procedure will be described with reference to time charts of the operation, current, signal, etc. of the earth leakage circuit breaker according to the first embodiment of the present invention.
The time chart of FIG. 3 (A) is a timing when ON of the test switch (test button), (B) is the input current of the constant voltage circuit, (C) is the luminous output of the photocoupler, (D) is the current of the ZCT test switch winding, (E) is the ZCT output signal (leakage detection circuit input signal), (F) is the thyristor drive output of the leakage detection circuit, G) is the current of the trip coil.
(1) testing switch (button) 11 at the rising edge of the (A) of FIG. 3 is an ON signal is emitted.
(2) smaller waveform to ON of the test switch 11 of FIG. 3 (B) is a standby current leakage. When the test switch 11 is turned on, a pseudo leakage current (B) flows.
(3) Since a half-wave rectified current flows through the primary side 9a of the photocoupler 9, light is emitted so as to correspond to the waveform (B).
(4) Since no current flows through the switching element 10 when the test switch 11 is in the switch OFF state, no current is generated in the test switch winding 3a of ZCT3. Since the switching element 10 is turned ON when the test switch 11 is in the ON state, a current is generated in the test switch winding 3a.

The current here is slanted due to the inductor component of ZCT. Actually, it is often an integrated waveform. In order to simplify the explanation, it is described as linear.
(5) Since the output signal (E) of the ZCT operates corresponding to the current (D) of the test switch winding 3a of the ZCT 3, the rising and falling operations (arrows) are performed.
(6) In FIG. 3, the drive output (F) of the thyristor 5 shows a case where an IC that detects the second rise of the ZCT output signal (E) is used. The reason for this is to prevent the circuit from being shut off when the ZCT output signal (E) rises due to noise or the like when the thyristor 5 is driven at the first rise.
In addition to this, an embodiment in which the operation is performed by detecting the third rise is also conceivable. In addition, since the rising interval is based on 50 or 60 Hz, an embodiment in which the reaction does not occur at an extremely short interval is also conceivable. For example, an embodiment may be considered in which the blocking operation is performed when the rising edge is detected again in about 18 to 22 msec after the rising edge of the first pulse is detected. Further, an embodiment in which the device does not operate unless the trailing edge at about 10 msec between the following 18 to 22 msec is detected can be considered.
(7) In order to perform a tripping operation when the leakage detection circuit 4 determines that a leakage has occurred in step (6) above, a current is passed through the tripping portion (coil) 6. The current to the trip unit 6 corresponds to the rise of the thyristor drive output (F) of the leakage detection circuit, and the trip operation is achieved.

According to the present invention, by using a half-wave rectifier as a power supply for a leakage breaker, for a leakage breaker that must operate from low voltage to high voltage, the heat loss of a power supply circuit such as a constant voltage circuit is reduced. The burden can be reduced.
In addition, according to the present invention, the use of a half-wave rectifier can reduce the voltage of the test circuit and contribute to the reduction of the insulation design.

1,1,1 ... Main circuit conductor (R phase, T phase, S phase)
2 ... Opening / closing contact part 3 ... Zero phase current transformer 3a ... Secondary winding 3b ... Winding for test switch (primary winding)
4 ... Leakage detection circuit 5 ... Thyristor (SCR)
6 ... tripping part 7 ... half-wave rectifier circuit (half-wave rectifier)
8 ... Constant voltage circuit 9 ... Photocoupler (Optical insulation means, pseudo-leakage current signal generation means)
9a: Light emitting side 9b: Light receiving side 10: Switching circuit (switching element)
11 ... Test switch 12 ... Zener diode 13 ... Zener diode

Claims (2)

An earth leakage circuit breaker that shuts off the AC power supply at the time of electric leakage,
A zero-phase current transformer in which a primary winding and a secondary winding are provided in the AC power source;
A leakage detection circuit;
A cutoff circuit that shuts off the AC power supply according to a leakage detection signal output by the leakage detection circuit;
A half-wave rectifier circuit connected to the AC power source;
A constant voltage circuit connected to the output side of the half-wave rectifier circuit and supplying power to the leakage detection circuit;
A half-wave rectification signal detection circuit for detecting a half-wave rectification signal output from the half-wave rectification circuit on the output side of the constant voltage circuit;
A current limiting circuit with active elements;
A switch for performing a test operation of the earth leakage breaker;
With
The current limiting circuit is connected in series via the switch to the output side of the constant voltage circuit,
The active element energized by turning on the switch as the test operation energizes the primary winding with the half-wave rectification signal detected by the half-wave rectification signal detection circuit, and the secondary winding is energized by the energization. The leakage detection circuit detects the current induced in the current and drives the cutoff circuit
An earth leakage circuit breaker characterized by that. 2. The earth leakage breaker according to claim 1, wherein the half-wave rectified signal detection circuit is a photocoupler .

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