JP2017091811A - Earth leakage circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an earth leakage circuit breaker capable of dealing with a large surge voltage without increasing the size of a surge absorber.SOLUTION: In the earth leakage circuit breaker, a series circuit of a trip coil 4 and a thyristor 7 is connected between two voltage lines X, Y of an electrical circuit L1 composed of single-phase three lines, and when electric leakage is detected by a zero-phase current transformer 1 arranged on the electrical circuit L1, the thyristor 7 is turned on, the trip coil 4 is tripped and a contact 2 connected to the electrical circuit L1 is opened. Voltage limitation means 8 for protecting the circuit is connected to the series circuit of the trip coil 4 and the thyristor 7 in parallel, the voltage limitation means 8 is composed of two surge absorbers 8a, 8b connected in series and a third surge absorber 9 is connected to the thyristor 7 in parallel.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an earth leakage circuit breaker, and more particularly to an earth leakage circuit breaker that is installed in a single-phase three-wire electric circuit and does not easily fail even when a large surge voltage is applied.

A conventional earth leakage breaker used for a single-phase three-wire circuit is configured as shown in FIG. 2, for example. As shown in FIG. 2, a zero-phase current transformer 21 is provided in the electric circuit L2, and a contact 22 that opens the electric circuit is provided on the power supply side. The IC has a leakage detection circuit 23 which is an IC, and a trip coil 24 for opening the contact 22; a thyristor 25 for tripping the trip coil 24; and a surge for protecting the circuit from surge voltage generated by lightning or the like. Based on the information of the zero-phase current transformer 21, the thyristor 25 was turned on to open the contact 22 by providing the absorber 26 and the like and the leakage detection circuit 23 based on the information of the zero-phase current transformer 21.
As shown in FIG. 2, an external surge voltage such as lightning is limited by connecting a surge absorber 26 in parallel with the thyristor 25 connected in series with the trip coil 24, that is, between voltage lines. Thus, an unnecessary operation is prevented and the circuit is protected so as not to exceed the break voltage of 25 (see, for example, Patent Document 1).

JP 2001-314031 A

  However, in the case of the above-described conventional configuration, if a large surge voltage is applied, the surge absorber 26 may break down beyond the current withstand capability of the surge absorber 26. Therefore, it is necessary to use a surge absorber with a large current withstand capability. was there. For this reason, the surge absorber has been increased in size and increased in cost.

  Therefore, in view of such problems, the present invention has an object to provide an earth leakage breaker that can cope with a large surge voltage without increasing the size of a surge absorber and hardly breaks down.

In order to solve the above-mentioned problems, the invention of claim 1 is directed to a zero-phase current transformer provided in a circuit in which a series circuit of a tripping coil and a thyristor is connected between two voltage lines of a single-phase three-wire circuit. When a leakage is detected by the detector, the thyristor is turned on, the tripping coil is tripped, and the contact provided in the circuit is opened to shut off from the power source. The voltage limiting means for protecting the circuit is connected in parallel, the voltage limiting means is two surge absorbers connected in series, and the thyristor is additionally connected with a surge absorber in parallel. It is characterized by that.
According to this configuration, since the voltage limiting means provided in the series circuit of the trip coil disposed between the voltage lines and the thyristor is constituted by two surge absorbers connected in series, the surge absorber has a withstand voltage of 1 It can be doubled compared to the case of only one. On the other hand, when the withstand voltage is doubled, a voltage exceeding the thyristor break voltage may be applied to the thyristor, but by connecting a surge absorber in parallel to the thyristor, unnecessary operation of the thyristor can be achieved. Can be prevented.

According to a second aspect of the present invention, in the configuration of the first aspect of the present invention, there is provided a neutral wire phase loss protection circuit that trips the tripping coil when a phase failure of the neutral wire occurs, A terminal for functioning the circuit is connected to an intermediate point between two surge absorbers connected in series.
According to this configuration, one of the two surge absorbers constituting the voltage limiting means can be used for protection of the neutral wire phase loss protection circuit, and there is no need to provide a separate surge absorber.

  According to the present invention, since the voltage limiting means provided in the series circuit of the trip coil and the thyristor arranged between the voltage lines is constituted by two surge absorbers connected in series, the surge absorber has a withstand voltage of 1 It can be doubled compared to the case of only one. On the other hand, when the withstand voltage is doubled, a voltage exceeding the thyristor break voltage may be applied to the thyristor, but by connecting a surge absorber in parallel to the thyristor, unnecessary operation of the thyristor can be achieved. Can be prevented.

It is a circuit diagram which shows an example of the earth-leakage circuit breaker which concerns on this invention. It is a circuit diagram of the conventional earth-leakage circuit breaker.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below in detail with reference to the drawings. FIG. 1 is a circuit diagram showing an example of a leakage breaker according to the present invention, which is a leakage breaker used for a single-phase three-wire circuit. A zero-phase current transformer 1 is provided for an electric circuit L1 composed of two voltage lines X and Y and a neutral line N, and a contact 2 for opening the electric circuit L1 from the power supply is provided on the power supply side. Reference numeral 3 denotes a control unit that opens the contact 2 when a leakage occurs, and includes a tripping coil 4, an IC leakage detection circuit 5, and the like.

  A thyristor 7 is connected to the tripping coil 4 in series. The thyristor 7 is controlled by the leakage detection circuit 5 and is turned on when the leakage detection circuit 5 detects the occurrence of leakage. A series circuit of the trip coil 4 and the thyristor 7 is disposed between the two voltage lines X and Y. Reference numeral 12 denotes a power supply side terminal, and 13 denotes a load side terminal.

A voltage limiting means 8 composed of two surge absorbers (first surge absorber 8a and second surge absorber 8b) is connected in parallel to the series circuit of the trip coil 4 and the thyristor 7. However, the two surge absorbers 8 have the same characteristics and are connected in series. As a result, the withstand voltage between X and Y is twice that of one surge absorber having the same characteristics.
Further, a surge absorber (third surge absorber) 9 is also connected to the thyristor 7 in parallel. The third surge absorber 9 is provided to protect the thyristor 7 and prevent unnecessary operation of the thyristor 7.

  A is a neutral wire phase loss detection circuit that detects the phase loss of the neutral wire N, and is connected to a terminal M for connection to the neutral wire N. The terminal M is connected between the first surge absorber 8a and the second surge absorber 8b, and the second surge absorber 8b is also used as a protective element for the terminal M (protective element for the neutral wire phase loss detection circuit A). Yes. By connecting the terminal M to the neutral wire N, the neutral wire phase loss protection circuit A becomes active.

The operation of the earth leakage circuit breaker configured as described above is as follows. When leakage occurs in the electric circuit L1, the zero-phase current transformer 1 detects it and inputs it to the leakage detection circuit 5 as a voltage signal. When the voltage signal exceeds a predetermined value, the leakage detection circuit 5 determines that leakage has occurred and turns on the thyristor 7. As a result, the tripping coil 4 is energized to perform the tripping operation, and the contact 2 is opened. Thus, the electric circuit L1 is cut off from the power source.
Further, when an external surge enters the electric circuit L1, as described above, a bypass is formed by the first surge absorber 8a and the second surge absorber 8b to protect the circuit including the thyristor 7, and the third surge absorber 9 A malfunction (unnecessary operation) of the thyristor 7 is prevented, and a high voltage is not applied.

Thus, since the voltage limiting means provided in the series circuit of the trip coil 4 and the thyristor 7 is composed of the two surge absorbers 8a and 8b connected in series, the internal resistance doubles and flows inside. The surge current is about half that of a single surge current. Therefore, the withstand voltage can be doubled as compared with the case where only one surge absorber is disposed between the voltage lines X and Y, and even if a large surge is applied, it is difficult to break down.
On the other hand, when the withstand voltage is doubled, there is a possibility that a voltage exceeding the break voltage of the thyristor 7 is applied to the thyristor 7, but by connecting the third surge absorber 9 to the thyristor 7 in parallel, Unnecessary operation of the thyristor 7 can be prevented.
In addition, if an overvoltage (400V to 200V) is applied by mistake, the third surge absorber 9 can excite the tripping coil 4 by passing a clip current for a long time (several to several tens of ms). It can be operated. Since the overvoltage is not continuously applied by this shut-off operation, it is difficult to break down.

Even when a surge voltage is applied, a current obtained by clipping the surge voltage by the third surge absorber 9 is tripped and flows to the coil 4 as in the case of applying an overvoltage, but the surge occurrence time is usually very short. Since it is ten to several μs, the time until the tripping coil 4 operates the mechanism to dissociate the contact cannot be taken, and the tripping operation does not occur.
The first to third surge absorbers 8a, 8b, and 9 can be elements used in a conventional 200V electric circuit.

  1 .... Zero phase current transformer 2 .... Contact 3 .... Control unit 4 .... Trip coil 5 .... Leakage detection circuit 7 .... Thyristor 8 .... Voltage limiting means 8a, 8b, ... 9. Surge absorber, A ... Neutral wire phase loss detection circuit, L1 ... Electric circuit.

Claims (2)

When a series circuit of a trip coil and a thyristor is connected between two voltage lines of a single-phase three-wire electric circuit, and a leakage is detected by a zero-phase current transformer provided in the electric circuit, the thyristor is turned on. In the earth leakage circuit breaker in which the trip coil is tripped and the contact provided in the electric circuit is opened to shut off from the power source,
In the series circuit of the trip coil and the thyristor, voltage limiting means for protecting the circuit is connected in parallel,
The voltage limiting means is two surge absorbers connected in series;
An earth leakage circuit breaker comprising a surge absorber connected in parallel to the thyristor. Having a neutral wire phase loss protection circuit that trips the tripping coil when a phase failure of the neutral wire occurs;
The earth leakage circuit breaker according to claim 1, wherein a terminal for functioning the neutral wire phase loss protection circuit is connected to an intermediate point of the two surge absorbers connected in series.

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