JP2708584B2 - Earth leakage breaker - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a method for connecting a surge absorbing element of a trip circuit of an earth leakage breaker, and in particular, to prevent a failure of a surge absorbing element such as a metal oxide varistor. The present invention relates to a discharge gap configuration and connection method suitable for the above.

[Conventional technology]

The conventional trip circuit connects the surge absorbing element in parallel with the trip coil as described in Japanese Patent Publication No. 1-18651, and contacts the auxiliary relay contact that energizes the trip coil in series with this parallel circuit. It is supposed to connect. As a result, the surge absorbing element is normally disconnected from the power supply, and a voltage is applied to the surge absorbing element only when a surge voltage is applied and when the contact of the auxiliary relay is closed. Therefore, even when a laser voltage is repeatedly applied to the surge absorbing element, the power supply voltage itself is not applied, and thus it is said that there is an effect that a short circuit phenomenon due to thermal destruction of the element can be prevented.

[Problems to be solved by the invention]

In the above prior art, when the contact of the auxiliary relay is closed,
Since the power supply voltage is applied to the surge absorbing element, if the surge absorbing element is deteriorated, the element is thermally destroyed and a short-circuit phenomenon occurs. In this case, the two-hour spread may cause a short-circuit between phases inside the earth leakage breaker. . For this reason, it is necessary to use a capacitor having a large overcurrent capacity, and there is a disadvantage that the size is increased.

It is an object of the present invention to solve these problems and to provide an earth leakage circuit breaker having a compact and highly reliable trip circuit.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a zero-phase current transformer, a detection circuit for comparing the outputs thereof, and energizing a relay, a trip coil energized by closing a relay contact, and a trip coil. An earth leakage circuit breaker comprising a breaking mechanism that operates to open by energization, comprising a two-terminal power surge absorbing element connected in parallel with a series circuit of a relay contact and a trip coil, and one of the power surge absorbing elements. Terminal is connected to the relay contact through a discharge gap, and the other terminal is electrically connected directly to the side of the trip coil opposite to the relay contact, and the discharge gap is formed including the contact of the relay contact. The power supply surge absorbing element is separated from the power supply, and a current flows through the power supply surge absorbing element only when a surge voltage is applied. .

In a preferred embodiment, the relay has a contact having a contact for energizing the trip coil and a discharge gap electrode provided adjacent to the contact, and one terminal of the power surge absorbing element has a discharge terminal. It is characterized by being electrically connected to the gap electrode.

In another preferred embodiment, the power surge absorbing element is incorporated in the relay, and one terminal of the power surge absorbing element forms a discharge gap between the power surge absorbing element and a contact of the relay contact.

In still another preferred embodiment, the relay has a contact having a contact for energizing the trip coil, and a pair of discharge gap electrodes provided independently of the contact, wherein the One is electrically connected to one terminal of the power supply surge absorbing element, and the other of the discharge gap electrodes is electrically connected to a contact. Further, since the gap is used as a part of the relay contact for energizing the trip coil as an electrode, the gap can be compactly built in the auxiliary relay. Further, in the embodiment in which the surge absorbing element is also incorporated, there is an effect that the size can be further reduced and the wiring work can be saved.
Since the power supply is reliably separated from the power supply by the discharge gap, the current flows only when a surge voltage is applied. Therefore, there is no thermal fire and, therefore, no short-circuit failure occurs.

[Action]

The discharge gap is electrically insulated at about twice the power supply voltage, but is electrically insulated at about four times the power supply voltage without insulation. Therefore,
Only when an excessive surge voltage is applied, the surge absorbing element operates, and the original purpose of surge absorption can be achieved. When a surge voltage is repeatedly applied, the deterioration proceeds as in the conventional example. However, since the surge absorbing element is always insulated from the power supply by the discharge gap, no short circuit occurs. The discharge gap can be compactly built into the auxiliary relay by configuring a part of the contact base of the relay contact as an electrode, so that the gap discharge does not affect other parts of the arc at all.

〔Example〕

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. A leakage current is detected by a zero-phase current transformer (ZCT) 2 penetrating the conductor 1 of each phase of the main circuit, and output to a leakage trip circuit 3. If the leakage current exceeds a set value, the leakage trip circuit 3 Operates, and the relay coil 6 is energized.
As a result, the relay contact 7 is closed, the power supply voltage is applied to the trip coil 8, and the circuit breaker opens. The power supply of the earth leakage trip circuit 3 is obtained from the main circuit by the transformer 9. The overvoltage protection of the earth leakage trip circuit 3 due to the intrusion of the induced lightning surge or the switching surge from the power supply is performed by the surge absorbing element 10 connected to the power supply line via the discharge gap 11. As shown in FIG. 2, the discharge gap 11 has a contact 7a 'of the movable contact 7a and a contact 7b' of the fixed contact 7b.
And the contact piece 7b 'and the contact piece 11a' of the gap piece 11a are integrally housed inside the auxiliary relay.

FIG. 3 shows a modification of this embodiment, in which a discharge gap is constituted by a fixed contact 7b and a gap piece 11b, and discharge is performed on the side surface of the fixed contact 7b and the tip of the gap piece 11b. In this modification, since the length of the gap piece is short and the contact 11a need not be used, there is an effect that a stable gap can be obtained at low cost.

A second embodiment of the present invention will be described with reference to FIGS. FIGS. 4 and 5 show an embodiment in which the movable contact 7a of the relay contact 7 is used as one of the discharge gap electrodes. In each of the embodiments, the discharge gap can be housed compactly, and the leakage breaker can be reduced in size and cost. .

A third embodiment of the present invention will be described with reference to FIG. FIG. 6 shows that the discharge gap 11 is constituted by gap pieces 11c and 11d,
It is housed in the auxiliary relay independently of the relay contact. A fourth embodiment of the present invention will be described with reference to FIG. FIG. 7 shows a structure in which a discharge gap 11 is formed by the lead 10a of the surge absorbing element 10 and the fixed contact 7b of the relay contact 7, and the surge absorbing element 10 and the relay contact 7 are integrally housed in an auxiliary relay.

〔The invention's effect〕

Since the present invention is configured as described above, it has the following effects.

(1) Since the discharge gap using a part of the relay contact is connected in series with the surge absorbing element, a compact earth leakage breaker free from failure due to surge voltage can be obtained.

(2) Since the discharge gap and the surge absorbing element are housed integrally in the auxiliary relay, assembly and wiring can be saved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an earth leakage breaker according to a first embodiment of the present invention, FIGS. 2 (a) and 2 (b) are a front view and a bottom view of an auxiliary relay used in this embodiment, respectively, and FIG. FIG. 4 is a front view of a main part of an auxiliary relay used in a modification of the present embodiment, FIG.
The figure is a circuit diagram of the earth leakage breaker in the second embodiment of the present invention,
FIG. 5 is a front view of a main part of an auxiliary relay used in this embodiment, FIG. 6 is a front view of a main part of an auxiliary relay used in an earth leakage breaker of a third embodiment of the present invention, and FIG. Fourth Embodiment of the Present Invention
FIG. 8 is a front view of a main part of an auxiliary relay used in the earth leakage breaker of the embodiment, and FIG. 8 is a circuit diagram of a conventional earth leakage breaker. 6: Relay coil, 7: Relay contact 8: Trip coil, 10: Surge absorbing element 11: Discharge gap

Claims (4)

(57) [Claims] 1. A zero-phase current transformer, a detection circuit for comparing the outputs thereof and energizing a relay, a trip coil energized by closing contacts of the relay, and opening by energizing a trip coil. An earth leakage circuit breaker comprising an operating cut-off mechanism, comprising a two-terminal power supply surge suction element connected in parallel with the relay contact and the series circuit of the trip coil, and one terminal of the power supply surge absorbing element is provided. The other terminal is connected to the relay contact via a discharge gap, and the other terminal is electrically connected directly to a side of the trip coil opposite to the relay contact, and the discharge gap is formed including a contact of the relay contact. The power supply surge absorbing element is separated from a power supply, and a current flows through the power supply surge absorbing element only when a surge voltage is applied. Earth leakage circuit breaker that. 2. The power supply surge absorbing element according to claim 2, wherein the relay has a contact having a contact for energizing the trip coil, and a discharge gap electrode provided adjacent to the contact. 2. The earth leakage breaker according to claim 1, wherein the electric circuit is electrically connected to the discharge gap electrode. 3. The power surge absorbing element is incorporated in the relay, and one terminal of the power surge absorbing element forms a discharge gap between the power surge absorbing element and a contact of the relay contact. 2. The earth leakage breaker according to claim 1. 4. The relay has a contact having a contact for energizing the trip coil, and a pair of discharge gap electrodes provided independently of the contact, and one of the discharge gap electrodes. 2. An earth leakage breaker according to claim 1, wherein said power supply surge absorbing element is electrically connected to one terminal of said power supply surge absorbing element, and said other of said discharge gap electrodes is electrically connected to said contact. .