JP2001314031A - Earth leakage breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an earth leakage breaker which does not bring about a hazardous fault condition even when an over-voltage is applied to the circuit. SOLUTION: One end of a power supply line 9 for supplying power to a control means 4 for determining the earth leakage and shielding is connected to a zero-phase current transformer 2 to detect the earth leakage of electric circuit, and a power supply current of control means which increases when an over-voltage is applied to the electric circuit is detected with the zero-phase current transformer 2 to realize shielding. The power supply line 9 connected to the zero-phase current transformer 2 is also used in common with a test circuit 10 connected to the zero-phase current transformer 2 for shielding test.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an earth leakage circuit breaker,
More specifically, the present invention relates to an earth leakage breaker that does not cause a dangerous failure state even when an overvoltage is applied.

[0002]

2. Description of the Related Art A circuit diagram of a conventional earth leakage breaker is shown in FIG. FIG. 3 shows an earth leakage circuit breaker used for a single-phase three-wire system, in which a zero-phase current transformer 2 is provided on an electric circuit composed of two voltage lines L1 and L2 and a neutral line N, and on the power supply side thereof. A contact 3 for opening an electric circuit is provided. Reference numeral 4 denotes a control unit for detecting a leakage and operating the contact 3 and includes a trip coil 5 and a voltage detection circuit 6 formed as an IC, and a zero-phase current transformer 2 when a leakage occurs.
The voltage is detected by the voltage detection circuit 6 when the voltage exceeds a predetermined threshold value, the thyristor 7 is turned on, the trip coil 5 is operated, and the contact 3 Open operation. Reference numeral 12 denotes a power supply side connection terminal of the electric circuit, and reference numeral 13 denotes a load side connection terminal.

[0003]

In the past, a rated voltage of 200 V was used.
400 V was applied to the earth leakage breaker by mistake, and the earth leakage breaker exploded, resulting in personal injury. This is considered to be due to the fact that the internal electronic components ruptured due to the application of the overvoltage to the earth leakage breaker, and the arc gas induced a line-to-line short circuit, increasing the internal pressure of the circuit breaker and rupture.

Here, in the above-mentioned earth leakage breaker, the power supply line 9 (9a, 9a, 9a) of the control unit connected to the voltage lines L1, L2.
9b), a voltage limiting element Z1 is provided as a protection element, and one voltage line L1 is further provided with a voltage limiting element Z2. Also, since two diodes D1 and D2 for rectification are connected to the power supply line 9, if an overvoltage is applied to the power supply circuit, these elements may fail in a short-circuit mode. And the earth leakage breaker may not open.

[0005] In view of the above problems, an object of the present invention is to provide an earth leakage breaker that does not cause a dangerous failure even if an overvoltage is applied to an electric circuit.

[0006]

To solve the above-mentioned problems, a first aspect of the present invention is to provide a zero-phase current transformer in an electric circuit, and to cut off the electric circuit from a power supply when a leakage is detected. In the above, the power supply of the control unit that determines the electric leakage and performs the cutoff operation is taken from the electric circuit, and one of the power lines of the power supply is passed through the zero-phase current transformer, and the control unit increases when an overvoltage is applied to the electric circuit. Power supply current is detected by a zero-phase current transformer and cutoff operation is performed.

According to a second aspect of the present invention, in the first aspect of the present invention, one of the power supply lines is shared with a test circuit passed through a zero-phase current transformer for performing an interruption operation test. .

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a circuit diagram showing an example of an earth leakage breaker of the present invention, which shows an earth leakage breaker used for a single-phase three-wire circuit, and the same components as those in FIG. ing. 3 is different from the circuit of FIG. 3 in that the test circuit 10 for testing the cutoff operation is different from the circuit of FIG.
0, and is connected to the voltage line L2 through the zero-phase current transformer 2.

The operation when an overvoltage is applied to the earth leakage breaker, that is, the operation when a high voltage is applied to a single-phase three-wire circuit will be described. When a high voltage is applied, the trip coil 5
There is a danger that an overvoltage is applied to the two voltage limiting elements Z1 and Z2, which are the elements of the control unit provided on the power supply side, and the two diodes D1 and D2, causing a failure in the short mode. It has been found that the leakage current increases immediately before failure of these devices as a characteristic of a semiconductor. For this reason, the leakage current increases, and the power supply line 9 of the control unit is increased.
The current flowing through the current detector also increases. This change in the current is detected by the zero-phase current transformer 2, converted into a voltage value by the resistor R1, detected by the voltage detection circuit 6, and the voltage exceeds a predetermined value. Then, a cutoff signal is output from the terminal a. With this signal,
The thyristor 7 is turned on to excite the trip coil 5 to trip, the contact 3 is opened, the electric circuit is released from the power supply, and the power supply to the control unit 5 is stopped.

In this way, even if an overvoltage is applied, the electric circuit is cut off immediately before the dangerous failure mode is reached. Therefore, even if a high voltage is applied by mistake or an excessive surge such as lightning is repeatedly applied, the internal circuit is not affected. Is also disconnected from the electric circuit at the same time, so that a dangerous failure state does not occur. In addition, even with such a configuration, it is not necessary to newly add an element or a component by sharing with the test circuit, and there is no increase in cost. In this case, one power supply line is shared by the test circuit, but may be independently passed through the zero-phase current transformer. In addition, the current consumption of the control unit always flows through the zero-phase current transformer, but is sufficiently smaller than the sensitivity current of the earth leakage breaker. A is a circuit connected to a neutral line to detect a neutral line open phase, and one voltage limiting element Z2 is connected as a protection element for its terminal M.

FIG. 2 is a circuit diagram showing another embodiment of the present invention. FIG. 2 is different from FIG. 1 in that the power supply line 9 of the control unit 4 is provided with a full-wave rectifier circuit using a diode bridge. Also in this case, similarly to FIG. 1, by passing one of the power supply lines 9 through the zero-phase current transformer 2, elements on the power supply side of the trip coil 5 in the control unit, that is, voltage limiting elements Z1, Z2, diodes D3, D4. , D5 and D6 are detected in the short-circuit mode immediately before the leakage current increased by the zero-phase current transformer 2 and converted into a voltage value by the resistor R1. When it is determined, a cutoff signal is output. With this output signal, the thyristor 7 is turned on, the trip coil 5 is excited, and the breaker trips.

Since the power supply to the control unit is stopped in this way, a dangerous failure mode does not occur. In addition, there is no newly added component, and there is no increase in cost.
In this case, the current consumption of the electronic control unit is always detected by the zero-phase current transformer. However, since the current consumption is sufficiently smaller than the sensitivity current of the earth leakage breaker, unnecessary operation is not performed.

[0013]

As described above in detail, according to the first aspect of the present invention, even if an overvoltage is applied, the electric circuit is cut off immediately before a dangerous failure mode is reached, so that an overvoltage is applied erroneously, lightning or the like. Even if an excessive surge is applied repeatedly, the internal circuit is protected and no dangerous failure occurs. According to the invention of claim 2, in addition to the effect of claim 1, by sharing with the test circuit, it is not necessary to add a new element or component, and the cost does not increase.

[Brief description of the drawings]

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

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

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

[Explanation of symbols]

2, zero-phase current transformers, 3 contacts, 4 control units, 5
Trip coil, 6 ... voltage detection circuit, 9 ... power line,
10. Test circuit.

Claims (2)

[Claims] 1. An earth leakage circuit breaker for providing a zero-phase current transformer in an electric circuit and disconnecting the electric circuit from a power supply when an electric leakage is detected. Taking one of the power supply lines of the power supply through the zero-phase current transformer, detecting a control unit power supply current that increases when an overvoltage is applied to the electric circuit with the zero-phase current transformer, and performing a breaking operation. And earth leakage breaker. 2. The earth leakage breaker according to claim 1, wherein one of the power supply lines is shared with a test circuit passed through a zero-phase current transformer for performing a breaking operation test.