JPH09182278A - Earth leakage protector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of parts when an earth leakage breaker function is provided in an apparatus. SOLUTION: A control circuit 6 is provided, instead of a current level judgment circuit. When the control circuit 6 judges that an output signal generated from a residual current transformer 5 is above a given level, a switch circuit connected in series with a coil of a relay 3 is opened. Then, contacts 31 and 32 of the relay 3 are opened to break the power fed to a driving circuit 2 of a load 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an earth leakage safety device which is provided in a gas appliance or other equipment and shuts off power supply to a load inside the equipment when an earth leakage occurs.

[0002]

2. Description of the Related Art A conventional earth leakage safety device is a so-called earth leakage breaker, which is formed separately from a device such as a gas appliance and is interposed between a power source and the device. Inside the power breaker, a pair of power lines are inserted, and a leakage detection circuit such as a zero-phase current transformer that generates an induced electromotive force when a leakage occurs and a power interruption mechanism that is interposed in the power line and interrupts the power line. And a current value determination circuit for activating the power cutoff mechanism when the output signal of the leakage detection circuit is greater than or equal to a predetermined value. Then, when the earth leakage breaker operates and shuts off the power supply line, power supply to the entire equipment is shut off.

[0003]

In some cases, the above-mentioned earth leakage breaker is not provided separately from the equipment but a function of the earth leakage breaker that shuts off the power supply at the time of earth leakage is built in the equipment. In this case, if the circuit of the earth leakage breaker and other structures are simply installed in the device, all the parts required for the earth leakage breaker must be newly installed, and the number of parts of the device increases.

In view of the above problems, an object of the present invention is to provide an earth leakage safety device capable of reducing the number of parts when incorporating the same function as an earth leakage breaker into a device.

[0005]

In order to achieve the above object, the present invention relates to a gas leakage safety device provided in a gas appliance or other equipment for shutting off power supply to a load in the equipment when a leakage occurs. A control circuit for controlling the load, the output signal from the leakage detection circuit is input to the control circuit for interrupting the power supply line. It is characterized in that the control circuit operates the power cutoff mechanism to cut off the power supply to the load when it is judged by the calculation whether or not the leakage has occurred.

The control circuit may be supplied with power from a power supply line on the upstream side of the power cutoff mechanism and supplied with power regardless of the operating state of the power cutoff mechanism.

In the earth leakage breaker, a dedicated current value judging circuit composed of electronic parts was provided as an indispensable circuit. However, if the control circuit for controlling the equipment is made to judge the occurrence of earth leakage by the arithmetic processing, The current value determination circuit can be completely eliminated while maintaining the same function as that of the earth leakage breaker.

When the earth leakage breaker is used, the electric power supply to the entire equipment is cut off when the electric leakage occurs, and therefore the electric power supply to the control circuit is also cut off. Therefore, it is not possible to know that the leakage has occurred until the leakage breaker is confirmed. However, if power is supplied to the control circuit from the power supply side from the power cutoff mechanism, power will continue to be supplied to the control circuit even if leakage occurs and the power cutoff mechanism operates. Therefore,
For example, it is possible to know the occurrence of the electric leakage at a glance by notifying the display unit of the device of the occurrence of the electric leakage.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Referring to FIG. 1, reference numeral 1 is an outlet for receiving a reduction power from a power source, which is connected to a device A such as a gas appliance to supply power. The outlet 1 is connected to the control board B via the power lines 11 and 12.
The load 21 such as a motor connected to the load driving circuit 2 provided above is driven.
The contact point 31 of the relay 3 is connected to each of the power supply lines 11 and 12.
32 is interposed, and the power lines 11 and 12 are connected and disconnected by the operation of the relay 3. The exciting coil of the relay 3 is connected to both power supply lines 11 and 12 via the switch circuit 4, and both contacts 31 and 32 are opened and closed in conjunction with the opening and closing of the switch circuit 4. On the other hand, a zero-phase current transformer 5 that surrounds the power supply lines 11 and 12 is provided. The zero-phase current transformer 5 is composed of an induction coil. In a state where no leakage occurs, the electromotive forces induced by the currents in both power supply lines 11 and 12 cancel each other out, and the zero-phase current transformer 5 itself induces. No electromotive force is generated. On the other hand, when a leakage occurs, the electromotive force induced by the power supply lines 11 and 12 is out of balance and the induced electromotive force according to the magnitude of the leakage is output as an output signal. The output signal of the zero-phase current transformer 5 is input to the control circuit 6 via an A / D converter (not shown). Although not shown, the control circuit 6 is provided with a central processing element (CPU) for performing a calculation process based on a preset program, and the output signal from the zero-phase current transformer 5 has exceeded a predetermined value. In this case, the switch circuit 4 is opened by judging that the leakage has occurred by calculation. Then, the contacts 31 and 32 are opened and the load drive circuit 2
The power supply to is cut off.

By the way, the control circuit 6 has the above-mentioned contact points 31.
Power is supplied from the power supply lines 11 and 12 on the upstream side of the power supply 32. Even if the contacts 31 and 32 are opened and the power supply to the load drive circuit 2 is cut off, the power can be continuously supplied. Therefore, when it is determined that the electric leakage has occurred and the power supply to the load drive circuit 2 is cut off, the fact that the electric leakage has occurred is displayed on the display unit 61, and the user can be notified of the occurrence of the electric leakage. it can. Although not shown, the control circuit 6 includes a power transformer and a rectifier circuit, and the load drive circuit 2 is controlled by the control circuit 6 in a normal state where no electric leakage occurs.

[0011]

As is apparent from the above description, according to the present invention, when the function of the earth leakage breaker is built in the device, the current value judging circuit provided in the conventional earth leakage breaker can be omitted. It is possible to reduce the number of parts.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

[Explanation of symbols]

 1 Outlet 2 Load drive circuit 3 Relay 4 Switch circuit 5 Zero-phase current transformer 6 Control circuit

Claims (2)

[Claims] 1. A leakage safety device, which is provided in a gas appliance or other equipment and shuts off power supply to a load in the equipment when an electrical leakage occurs, in a leakage detection circuit and a power supply line, a power supply which shuts off the power supply line. When an output signal from the leakage detection circuit is input to the control circuit that has a cutoff mechanism and controls the load, and whether or not the leakage occurs in the control circuit by calculation and it is determined that the leakage has occurred, A leakage safety device characterized in that the control circuit operates the power cutoff mechanism to cut off power supply to a load. 2. The control circuit receives power from a power supply line upstream of a power cutoff mechanism and receives power regardless of the operating state of the power cutoff mechanism. Leakage safety device.