JP2818063B2 - Earth leakage breaker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an earth leakage circuit breaker, and more particularly to an earth leakage circuit breaker having high insulation reliability and low insulation cost between a secondary winding and a test winding of a zero-phase current transformer. is there.

[0002]

2. Description of the Related Art FIG.
FIG. 6 is a circuit diagram showing an example of a conventional earth leakage breaker as disclosed in Japanese Unexamined Patent Application Publication No. 6-206. In the figure, reference numeral 1 denotes an AC main circuit, 3 denotes a zero-phase current transformer through which the main circuit 1 passes and around which a secondary winding 3a and a test winding 3b made of, for example, an insulating winding are wound. A control circuit 5 having an input side connected between both ends of the secondary winding 3a of the phase current transformer 3, a thyristor 5,
The anode is connected to the high voltage side of the control circuit 4 via an electromagnetic trip device such as a relay 6 and a voltage drop element 8,
Its gate is connected to the control side of the control circuit 4 and its cathode is connected to the low voltage side of the control circuit 4. A rectifier circuit 7 has an AC side connected to an AC power supply, and the thyristor 5 and the relay 6 described above are connected in series between both ends of the DC side. Reference numerals 9 and 10 denote test switches and test resistors, respectively, which are connected in series with each other and connected between both ends of the AC power supply via the test winding 3b of the zero-phase current transformer 3.

[0003] The conventional earth leakage breaker is configured as described above, and when an earth leakage occurs in the main circuit 1, the zero-phase current transformer 3
Generates an output voltage at its secondary winding 3a. Control circuit 4
Amplifies this output voltage and applies it to the gate of the thyristor 5 to make the thyristor 5 conductive. As a result, the relay 6 is excited and switches its contact 6a. The power supply voltage of the control circuit 4 is obtained through the voltage drop element 8 from the output side of the rectifier circuit 7 that rectifies the AC power supply voltage. When the test switch 9 is closed, the zero-phase current transformer 3 is supplied from the AC power source through the test switch 9 and the test resistor 10.
A voltage applied across the test winding 3b generates an output voltage similar to that described above in the secondary winding 3a, and excites the relay 6.

FIG. 3 is a circuit diagram showing another example of a conventional earth leakage breaker as disclosed in Japanese Utility Model Application Laid-Open No. 62-82546. This earth leakage breaker is of a transformer insulation type and has a voltage of the main circuit 1 of, for example, 100V, 200V.
Transformer 1 that steps down V, 415V etc. to about 20V
1 from the secondary side of the transformer 11 to the control circuit 4,
The power supply voltage for the test circuits 9-10 is used.

[0005]

In the prior art shown in FIG. 2, since the test switch and the test resistor are connected to the side of the AC power supply having no voltage drop element, the secondary winding of the zero-phase current transformer, A potential difference of about 180 V occurs between the test windings. Therefore, it is necessary to strengthen the insulation between the secondary winding and the test winding. For example, there is a problem that the zero-phase current transformer needs to be large and the insulation cost must be increased.

In the conventional example shown in FIG. 3, since a transformer is used, a potential difference larger than 20 V does not occur between the secondary winding and the test winding of the zero-phase current transformer. Therefore, 2
Although it is not necessary to enhance the insulation between the secondary windings, there is a problem that the transformer is expensive anyway and the earth leakage breaker becomes large as a result of using the transformer.

Accordingly, the present invention has been made to solve these problems, and the insulation reliability is high and the cost is low without increasing the size of the zero-phase current transformer or the earth leakage breaker itself. The purpose is to obtain an earth leakage breaker.

[0008]

An earth leakage circuit breaker according to the present invention is a zero-phase current transformer in which an AC main circuit is penetrated and a test winding comprising a secondary winding and an electric wire having a thin insulating film is wound. And an alternating current through a voltage drop element between both ends of the main circuit.
A rectifier circuit whose side is connected, and the rectifier circuit between both ends of the main circuit.
The voltage drop element is connected in series with the test winding.
Connected between the main circuit side and one end of the test winding.
And a test switch and a test resistor connected to the DC side of the rectifier circuit to supply a power supply voltage.
A control circuit connected between both ends of the next winding, and an electromagnetic trip device controlled by the control circuit and connected in series between the main circuit side of the voltage drop element and the low voltage side of the control circuit And a thyristor and a circuit breaker that is opened and closed by the electromagnetic trip device.

[0009]

According to the present invention, since the power supply voltage of the control circuit is stepped down from the main circuit by the voltage drop element and rectified by the power regulating circuit and taken in, and an enamel wire or the like is used for the test winding, the zero-phase current transformer is used. The potential difference between the secondary winding and the test winding is very low.

Embodiment 1 FIG. FIG. 1 is a circuit diagram showing one embodiment of an earth leakage circuit breaker according to the present invention, in which 2 is a circuit breaker opened and closed by an electromagnetic trip device 6, and 3 bA is a test of a zero-phase current transformer 3. Although it is a winding, it is made of an electric wire with a thin insulating film, for example, an enameled wire, instead of a thick insulating winding as in the conventional example. In this embodiment, the power supply voltage of the control circuit 4 is taken down from the main circuit 1 by the voltage drop element 8 and rectified by the rectifier circuit 7. Further, the terminal of the voltage drop element 8 connected to the main circuit side is connected via a circuit consisting of an electromagnetic trip device 6-thyristor 5-rectifier circuit 7 or a test resistor 10-test switch 9-zero-phase current transformer. 3 is connected to the other side of the main circuit 1 via a circuit consisting of three test windings 3bA.

In the earth leakage breaker configured as described above, the zero-phase current transformer 3 detects that an earth leakage has occurred in the main circuit 1 and generates an output voltage on its secondary winding 3a. The output voltage is amplified and the control circuit 4 applies the thyristor 5 to the thyristor 5 so that the thyristor 5 is turned on and the electromagnetic disconnecting device 6 is excited, so that the circuit breaker 2 is tripped from the main circuit 1. The operation at the time of the test is the same as the conventional example.

[0012]

As described above in detail, the present invention relates to a zero-phase current transformer in which an AC main circuit is penetrated and a test winding comprising a secondary winding and a thin electric wire having an insulating skin is wound. , The AC side is connected between both ends of the main circuit via a voltage drop element
And the test winding between both ends of the main circuit.
And the mains of the voltage drop element in series connection with each other.
Test connected between the circuit side and one end of the test winding
A switch and a test resistor, a control circuit connected to the DC side of the rectifier circuit for supplying a power supply voltage and connected between both ends of the secondary winding, and the voltage drop element controlled by the control circuit and The electromagnetic trip device and the thyristor connected in series with each other between the main circuit side and the low voltage side of the control circuit, and the circuit breaker opened and closed by the electromagnetic trip device are provided. The insulation between the secondary winding and the test winding of the zero-phase current transformer is simplified, so that the zero-phase current transformer can be reduced in size, and thus the zero-phase current transformer can be easily housed in the earth leakage breaker. Therefore, the earth leakage breaker itself can be downsized, (2) the insulation cost is reduced, (3) the reliability of insulation is increased, and (4) in the case of using an enamel wire, a toroidal winding material can be used. Low test winding cost Becomes, and in the case of using the enamel wire is an effect that thin since it is possible to increase the number of turns of the test winding, thus fabricating a low-sensitivity earth leakage breaker.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of an earth leakage breaker according to the present invention.

FIG. 2 is a circuit diagram showing an example of a conventional earth leakage breaker.

FIG. 3 is a circuit diagram showing another example of a conventional earth leakage breaker.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main circuit 2 Breaker 3 Zero-phase current transformer 3a Secondary winding 3bA Test winding 4 Control circuit 5 Thyristor 6 Electromagnetic trip device 7 Rectifier circuit 8 Voltage drop element 9 Test switch 10 Test resistance

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01H 83/04 H01H 83/02

Claims (1)

(57) [Claims] 1. A zero-phase current transformer having an AC main circuit penetrating therethrough and a secondary winding and a test winding comprising a thin electric wire having an insulating film wound thereon, and a voltage drop element provided between both ends of the main circuit. Via
Rectifier circuit to which the AC side is connected, and both ends of the main circuit
The test winding and the voltage in a series connection with each other
Between the main circuit side of the falling element and one end of the test winding
A test switch and a test resistor connected thereto, a control circuit connected to the DC side of the rectifying circuit to supply a power supply voltage, and connected between both ends of the secondary winding; An electromagnetic trip device and a thyristor controlled by a circuit and connected in series between a main circuit side of the voltage drop element and a low voltage side of the control circuit; and a circuit breaker opened and closed by the electromagnetic trip device. An earth leakage breaker comprising: