JP2001251753A - Ground leakage breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent malfunction of a trip mechanism caused by misfiring of a thyristor, in a ground leakage breaker which uses a transformerless power source. SOLUTION: Energization of a trip coil caused by misfiring due to the noise in the thyristor connected to the tripping coil directly is prevented, by connecting between the anode and cathode of the thyristor, a capacitor having the same capacitance as a trigger capacitor connected between the anode and gate of the thyristor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an earth leakage breaker used for protecting an electric circuit, and more particularly to a trip circuit.

[0002]

2. Description of the Related Art As shown in FIG. 3, a block configuration of an earth leakage circuit breaker includes a rectifier circuit A, a power supply circuit B, a detection circuit C, a trip circuit D, a trip device E, a current transformer F, and a trip mechanism G.
Consists of When a current leak is detected by the current transformer F, the tripping mechanism G is operated to protect the electric circuit.

A power supply circuit uses a transformerless power supply to reduce the size of an earth leakage breaker. Further, the tripping device uses a suction-type tripping device which is superior in terms of stability of characteristics and production yield. Since the tripping circuit directly drives the suction type tripping device, it is necessary to achieve a high breakdown voltage, and has a configuration in which a plurality of thyristors are connected in series.

FIG. 4 shows a conventional trip circuit of the earth leakage breaker having the block configuration. The trip circuit is a first-stage thyristor 1, a capacitor 2 and a resistor 3 connected between the gate and cathode of the thyristor, a second-stage thyristor 4, a resistor 5 connected between the gate and cathode of the thyristor, and an anode.・ Trigger capacitor 6, connected between gates
It comprises a noise absorbing capacitor 7 and a tripping coil 8.

When the detection circuit C detects a leakage, the circuit C
Is output to the gate of the first-stage thyristor 1, and the first-stage thyristor 1 is turned on. This gives 2
A trigger current flows through the gate of the thyristor 4 through the capacitor 6, the second thyristor 4 fires, a current flows through the trip coil 8, and a trip mechanism G (details not shown).
Operates.

[0006]

The present configuration has a simple configuration with a small number of components, but on the other hand, when large noise is applied from the R or T phase of the electric circuit and the noise absorption capacitor 7 causes insufficient noise absorption, Noise enters the gate of the second stage thyristor 4 via the capacitor 6, causing a potential difference between the gate and the cathode to easily cause erroneous firing of the thyristor 4, and the tripping mechanism G to malfunction. Was.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a leakage detector using a transformerless power supply and a tripping device, to improve the noise immunity of the tripping circuit and prevent the tripping mechanism from malfunctioning due to erroneous firing of the thyristor. And

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a trip circuit which has a capacitance equivalent to that of a trigger capacitor connected between an anode and a gate between an anode and a cathode of a thyristor directly connected to a trip coil. Can be achieved by connecting the above-mentioned capacitors so that a potential difference between the gate and the cathode does not occur even when noise enters.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described based on an embodiment with reference to FIG. The embodiment of FIG. 1 shows two thyristors 1 and 4 connected in series, a capacitor 2 connected between the gate and cathode of the first stage thyristor, a resistor 3, and a gate and cathode of the second stage thyristor 4. This is a high withstand voltage trip circuit including a resistor 5, a diode 9, a capacitor 6 connected between the anode and the gate, a capacitor 10 connected between the anode and the cathode, and a trip coil 8. In this embodiment, the thyristors 1 and 4 each have a peak repetitive reverse voltage of 600 V, a capacitance of the capacitor 10 of 1 μF / 10 V,
Resistor 3 is 330 kΩ, 1/10 W, resistor 5 is 10 k
Ω, 1/10 W, 90 ° V, 0.4 A for die auto 9, capacitors 6 and 10 having approximately the same capacity, and 0.01 μF / 630 V in each case. The diode 9
Is incorporated to ensure circuit stability.

In the present configuration, when noise enters, there are two routes for entering the noise: one passing through the capacitor 6 and the other passing through the capacitor 10. However, since the capacitors 6 and 10 have approximately the same capacitance, the voltage drop is almost the same. As a result, no potential difference occurs between the gate and the cathode, and no gate current flows, so that erroneous firing does not occur.

In the case of FIG. 4 which is a conventional comparative example, the diode 9 and the capacitor 1 shown in FIG.
It has a configuration excluding 0, and the values of the resistors and capacitors used are the same.

As an effect of the present invention, it was confirmed that the noise immunity of the present embodiment was improved by about 1.5 times or more in the relative comparison as compared with the comparative example. In the example and the comparative example, the power supply voltage range input to the rectifier circuit is:
80-484V.

Further, as shown in FIG. 2, by connecting the capacitor 11 between the anode and the cathode of the first-stage thyristor, the noise immunity can be further improved. In this embodiment, the capacitance of the capacitor 11 is 0.01 μF / 63.
0 V was applied. The characteristic values of the other components and the power supply voltage range input to the rectifier circuit were all the same as those in FIG. It was confirmed that the noise immunity in the present example was improved by about 1.7 times or more in the relative comparison as compared with the comparative example.

[0014]

According to the present invention, in the earth leakage breaker using the transformerless earth leakage detection circuit, the noise resistance of the high withstand voltage trip circuit is improved, and the malfunction of the trip mechanism due to the false firing of the thyristor is prevented. A prevented trip device can be provided.

[Brief description of the drawings]

FIG. 1 is a trip circuit connection diagram showing an embodiment of the present invention.

FIG. 2 is a trip circuit connection diagram showing another embodiment of the present invention.

FIG. 3 is a block diagram of an earth leakage breaker.

FIG. 4 is a connection diagram of a conventional trip circuit.

[Explanation of symbols]

 1, 4: thyristor 2, 6, 7, 10, 11: capacitor 3, 5: resistor 9: diode 8: trip coil

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Eietsu Sato 46-1, Tomioka, Oji, Nakajo-cho, Kitakanbara-gun, Niigata Prefecture Within the Industrial Equipment Group of Hitachi, Ltd. 1 F-term within the Hitachi, Ltd. Industrial Equipment Group (reference) 2G014 AA16 AB09 AB53 5G058 BB02 BC16 BD07

Claims (1)

[Claims] 1. An earth leakage circuit breaker having a trip device and using a transformerless power circuit in a power circuit section, wherein the trip circuit comprises a plurality of thyristors connected in series and is directly connected to a trip coil. An earth leakage breaker characterized in that a capacitor having a capacity equivalent to that of a trigger capacitor connected between the anode and the gate of the thyristor is connected between the anode and the cathode of the thyristor.