JPH02294217A - Earth-leakage circuit breaker - Google Patents

Abstract

PURPOSE:To discriminate why the power supply is interrupted by controlling the lighting of an LED by a control circuit (IC). CONSTITUTION:The leak is detected by a zero-phase-sequence current transformer 14 and transmitted to an IC9. A leak detection circuit (SCR)4 is turned ON by the signal from the IC9 and the cable run is interrupted by conducting the current to a leak trip coil 6. At this moment, an LED 23 is not lighted because only a series circuit of a diode 3, the SCR4, a diode 5 and the leak trip coil 6 is constituted against a power source 1. Consequently, if the LED 23 is not lighted, it can be judged as leak. In case an external circuit 15 is abnormal, it is detected by the zero-phase-sequence current transformer 14, the IC9 works to turn ON the SCR4, the current conducts to the leak trip coil 6 to interrupt the cable run and the LED 23 is lighted, so that it can be judged as no power interruption resulting from the leak.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an earth leakage breaker used in electric water heaters, smoke detectors, earthquake detectors, and the like.

2. Description of the Related Art Conventionally, in an earth leakage breaker used in an electric water heater, etc., a switch mechanism for a sensor for preventing excessive rise in temperature of the electric water heater, etc. It is connected to the. Therefore, in the event of an electrical leakage, the electrical leakage detection circuit operates directly and energizes the electrical leakage tripping coil, thereby interrupting the electrical circuit.Also, in electric water heaters, etc., the temperature exceeds the set value. If the temperature rises to above, a signal is given to the sensor from an overtemperature rise prevention device connected as an external circuit, thereby detecting the abnormal state of the overheating and turning on the test circuit of the earth leakage breaker;
It is configured to interrupt the electrical circuit.

In such an earth leakage breaker, a test switch for testing whether the earth leakage breaker is operating normally or not and an overheat prevention device for an electric water heater are connected.

Problems to be Solved by the Invention In such conventional earth leakage circuit breakers, it is not possible to determine whether the circuit has been activated due to a current leakage or an abnormality in an external circuit such as an electric water heater. Therefore, there are problems in terms of technical standards when handling earth leakage circuit breakers.

Means for Solving the Problems In an earth leakage breaker comprising an electric circuit breaking mechanism, an earth leakage tripping coil for driving the electric circuit breaking mechanism, a zero-phase current transformer for detecting electric leakage, an earth leakage detection circuit, and a switching circuit, the zero-phase A test circuit having a test switch that generates a pseudo earth leakage current is connected to the current transformer, and a circuit in which the test switch, a diode, and a photothyristor diode are connected in antiparallel is incorporated into the test circuit, and the earth leakage detection is performed. A series circuit of the photothyrisk thyristor and an LED was connected in parallel with the thyristor in the circuit.

In the case of electrical leakage in the working circuit, the photothyristor does not operate even if the electrical leakage detection circuit operates, so the LED does not light up, and when an abnormal signal from an external circuit or the test circuit operates, the photothyristor does not operate. When turned on, the LED lights up and a pseudo earth leakage current is generated, which is detected by the zero-phase current transformer and the earth leakage breaker operates, so the LE
By looking at the lighting state of D, it is easy to determine whether the operation is caused by a current leakage or by an external circuit or test push button.

Example An embodiment of the present invention will be described based on the drawings.

First, a surge absorber 2 indicated as TNR is connected to the power supply l, and D1 is connected in parallel with this surge absorber 2.
The diode 3 and the SCR 4 that constitute the earth leakage detection circuit
A series circuit of a diode 5 and an earth leakage tripping coil 6 is connected.

The SCR4 and the diode 5 have R1
An IC 9 as a control circuit is connected through a resistor 7 and a capacitor 8, C1.

Moreover, between the gate of the SCR4 and the ground side, C2
The capacitor 10 is connected to the IC 9, and the IC 9 is also connected to the IC 9 via a capacitor l1. Further, a resistor 12 R2 is connected together with the resistor 7 between the anode and cathode of the SCR 4.

Next, Z is connected to the IC 9 via a resistor 13 of R.
A zero-phase current transformer 14 labeled CT is connected. The test circuit configured through the second zero-phase current transformer 14 section is as follows:
An external terminal 16 to which an external circuit 15 such as an overtemperature protection device for an electric water heater or the like is connected, a diode 17 of D, a diode 19 of a photothyristor 18, and a resistor 20 of R4, which are connected in antiparallel to each other. series circuit and T
．． It consists of test switches 21 labeled S for operating the test circuit, and these are connected to the power source 1.

Furthermore, R. A series circuit including a resistor 22, an LED 23, a thyristor 24 of the photothyristor 18, and a reset switch 25 is connected.

In such a configuration, the test switch 21 is open in a normal state, and in this state, the test switch 21 operates due to a leakage on the power supply l side or an abnormality in the external circuit l5. For example, if there is a current leakage, the zero-phase current transformer 14 detects this and the IC
9, the SCR 4 is turned on by the signal from the IC 9, and the earth leakage tripping coil 6 is energized. As a result, a switch mechanism (not shown) is operated to cut off the electrical circuit.

At this time, for power supply l, diode 3, scR4,
Since only a series circuit of the diode 5 and the earth leakage tripping coil 6 is configured, the LED 23 is not lit. Therefore, when the electric circuit is cut off without the LED 23 lighting up, it can be determined that there is a current leakage.

Next, when the external circuit 15 becomes abnormal, a current flows through the circuit of the external terminal 16, generating a pseudo leakage current, and the zero-phase current transformer 14 detects this state. At the same time, the diode 19 of the photothyristor 18 lights up, turning on the thyristor 24.

As a result, the IC 9 is activated by the signal from the zero-phase current transformer 14 to turn on the SCR 4, energize the earth leakage tripping coil 6 to cut off the electric path, and also turn on the thyristor 24, so that the LED 23 lights up. This makes it possible to determine that the power supply is not cut off due to electrical leakage. In this case, the LED
23 continues to be lit, after performing the necessary processing, the reset switch 25 is turned off to turn off the thyristor 24 of the photothyristor 18.

Further, in the case where there is no current leakage and the external circuit 15 is normal, the test switch 2l is turned on in order to test whether or not the operating state of the B current detection circuit is normal. As a result, as in the case described above, the IC 9 is activated by the signal from the zero-phase current transformer 14, turns on the SCR 4, energizes the earth leakage tripping coil 6 to cut off the electric path, and turns on the thyristor 24. As a result, the LED 23 lights up.

Thereby, it is possible to test whether the cutoff function of the power supply circuit is normal or not, and it can be determined from the lighting of the LED 23 that the power supply is cut off due to the operation of the test switch 21.

Effects of the Invention As described above, the present invention provides an earth leakage breaker that includes an electric circuit interrupting mechanism, an earth leakage tripping coil that drives the electric circuit interrupting mechanism, a zero-phase current transformer that detects electric leakage, an earth leakage detection circuit, and a switching circuit. A test circuit having a test switch that generates a pseudo leakage current is connected to the zero-phase current transformer, and a circuit in which the test switch, a diode, and a photothyristor diode are connected in antiparallel is connected to the test circuit. Since a series circuit of the thyristor and LED of the photothyristor is connected in parallel with the thyristor in the earth leakage detection circuit, in the case of an earth leakage in the electric circuit, the photothyristor will not operate even if the earth leakage detection circuit operates. , L
If the ED does not light up and there is an abnormal signal from the external circuit or the test switch is pressed, the photothyristor turns on and lights up the LED.
If you look at the lighting status of the ED, it may have been activated due to an electrical leakage.
This has the effect of making it possible to determine whether the problem is caused by an external circuit or a test switch.

The drawing is a circuit diagram showing an embodiment of the present invention.

4 ・Earth leakage detection circuit, 6...Earth leakage tripping coil, 1
4... Zero-phase current transformer, 15... External circuit, 17... Diode, 19... Photothyristor diode, 2
1...Test switch, 23...LED, 24. Thyristor application for photothyristor Person Toshiba Lighting & Technology Corporation

[Brief explanation of the drawing]

Claims (1)

[Claims] In an earth leakage breaker that includes an electric circuit breaking mechanism, an earth leakage tripping coil that drives the electric circuit breaking mechanism, a zero-phase current transformer that detects electric leakage, an electric leakage detection circuit, and a switching circuit, a pseudo A test circuit having a test switch that generates an earth leakage current is connected, and a circuit in which the test switch, a diode, and a photothyristor diode are connected in antiparallel is built into the test circuit, and the circuit is connected in parallel with the thyristor in the earth leakage detection circuit. An earth leakage breaker characterized in that a series circuit of a thyristor of the photothyristor and an LED is connected.