JP2011150811A - Electronic circuit breaker - Google Patents

Abstract

To provide an electronic circuit breaker in which component parts can be easily assembled and replaced, and specification of rated current can be easily changed.
A current transformer 11 converts a current flowing in an electric circuit into a secondary current and outputs the secondary current. The trip control circuit 12 generates a trip signal when the value of the secondary current output from the current transformer exceeds a threshold value. When receiving the trip signal, the trip device 13 operates the switching device 8 to cut off the electric circuit. The current transformer 11 is configured as a unit in the overcurrent detection unit 100, and the trip control circuit 12 and the trip device 13 are configured in the trip control unit 200, respectively. When changing the rated current for interrupting the electric circuit, the threshold value of the trip control circuit 12 is maintained as it is, and the number of turns of the secondary coil constituting the current transformer 11 is changed.
[Selection] Figure 1

Description

  The present invention relates to an electronic circuit breaker that protects an electric circuit from an overcurrent, and relates to a structure in which its components are unitized.

  Circuit breakers have mechanical and electronic overcurrent tripping methods to protect the current path (electric circuit) from overcurrent. In the mechanical tripping method, the bimetal is bent when an overcurrent is generated, and a trip mechanism is activated to interrupt the electric circuit. In the electronic trip method, an overcurrent flowing through a conductor is detected by a current transformer, and a trip device is operated by a trip control circuit to perform a trip operation. In the case of the electronic type, the current is detected by a current transformer, and the cut-off operation is performed when the detected current exceeds the predetermined value. It's easy.

  FIG. 3 is a structural diagram showing an example of a conventional electronic circuit breaker. The circuit breaker has switching contacts 3 and 5 that block the electric paths 2, 4, and 6. The switching contacts 3 and 5 are opened and closed by operating the handle 9 and are blocked by the operation of the tripping device 13. In the tripping mechanism, the current transformer 11 detects the energizing current in the circuit breaker, and the tripping control circuit 12 drives the tripping device 13 when the detected current exceeds a predetermined value (rated current). The switching contacts 3 and 5 are shut off.

  In this configuration, the current transformer 11, the trip control circuit 12, and the trip device 13 are each integrally incorporated in the housing 10 and closed with a cover. Therefore, even when it is desired to replace some parts due to deterioration of the component parts, it is difficult to replace only the target part.

  In this regard, Patent Document 1 discloses a structure in which an electronic circuit part is unitized so as to be detachable from a cover so that only a circuit part can be removed and replaced in the event of a failure.

Japanese Unexamined Patent Publication No. 7-212217

  The circuit breaker has various rated current specifications depending on its application, and needs to cope with it. The conventional circuit breaker has a structure in which each component is integrally incorporated in the casing, and the component is often a dedicated component at each rated current. For this reason, parts cannot be easily replaced, and it is difficult to deploy the parts to different rated currents. As a result, it took a lot of man-hours in terms of inventory and quality control of the parts, which caused the cost of the parts to be expensive.

  In the technique disclosed in Patent Document 1, by making the electronic circuit part a unit and making it detachable, only the circuit part can be removed and replaced in the event of a failure. However, replacement of components when changing the rated current specification is not considered. Even if it is assumed that the electronic circuit is replaced in order to change the rated current according to the method of Patent Document 1, the following problem is raised. One is that the current transformer's conversion characteristics are non-linear, so the same current transformer cannot be shared for all rated currents, and the other is that the electronic circuit is compared to other components. It is expensive.

  In view of the above problems, an object of the present invention is to provide an electronic circuit breaker in which component parts can be easily assembled / replaced and the specification of rated current can be easily changed.

  In order to solve the above-described problems, an electronic circuit breaker according to the present invention includes a current transformer that converts a current flowing in an electric circuit into a secondary current and outputs the secondary current, and a value of the secondary current output from the current transformer. A trip control circuit that generates a trip signal when the value of the secondary current exceeds the threshold, and a trip device that operates the switchgear and interrupts the electrical circuit when the trip signal is received The current transformer is configured as an overcurrent detection unit, and the trip control circuit and the trip device are configured as a trip control unit.

  Here, when changing the value of the overcurrent when interrupting the electric circuit, the threshold set in the trip control circuit is maintained as it is, and by changing the number of turns of the secondary coil in the current transformer, The secondary current output from the current transformer is not changed.

  Also, the overcurrent detection unit and the tripping control unit are each housed in an elastic material case, and each unit is integrated by engaging an opening and a hook provided in each case. .

  According to the present invention, it is possible to provide an electronic circuit breaker in which component parts can be easily assembled and exchanged by making the component parts into units, and the rated current specification can be easily changed.

1 is a structural diagram showing an embodiment of an electronic circuit breaker according to the present invention. The figure which shows the assembly method of an overcurrent detection unit and a trip control unit. FIG. 6 is a structural diagram showing an example of a conventional electronic circuit breaker.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a structural diagram showing an embodiment of an electronic circuit breaker according to the present invention. The same elements as those of the conventional electronic circuit breaker shown in FIG.

  In the circuit breaker, a current interrupting part by the switching contact 3 is inserted in the middle of electric circuits (conducting conductors) 2, 4, 6 from the power supply side terminal 1 to the load side terminal 7. The switching contact 3 is opened and closed by operating the switching device 8 with the handle 9. The switching contact 3 is opened when the tripping device 13 is operated. The tripping device 13 causes the plunger to protrude by exciting the trip coil, and operates the opening / closing device 8. The current transformer 11 detects an energization current of the energization conductor 6 in the circuit breaker, trips a current signal corresponding to the magnitude thereof, and supplies it to the control circuit 12. When the control circuit 12 determines that the energization current is in an overcurrent state exceeding a predetermined value (rated current), the control circuit 12 drives the tripping device 13 to open the switching device 8 and open the switching contact 3. Is.

  In this embodiment, the trip mechanism is configured in the housing 10 by separating it into two units, that is, an overcurrent detection unit 100 and a trip control unit 200. The overcurrent detection unit 100 houses a current transformer 11 installed at each pole according to the number of phases of the power supply, converts the load current flowing through the conducting conductor 6 into a minute secondary current and outputs it. The current transformer 11 includes a secondary coil 14 and a yoke 15, and a secondary current is induced in inverse proportion to the number of turns of the secondary coil 14. The induced secondary current is output to the trip control unit 200.

  The trip control unit 200 houses the trip control circuit 12 and the trip device 13, operates the trip device 13 in accordance with the secondary current output from the overcurrent detection unit 100, and the electric circuit (switch contact 3). Shut off. At that time, the trip control circuit 12 compares the value of the secondary current output from the overcurrent detection unit 100 with a predetermined value (threshold value). Send a trip control signal to.

Assuming that the number of turns of the secondary coil 14 of the overcurrent detection unit 100 is N, the relationship between the energization current (rated current) Ic and the threshold Ith of the trip control circuit 12 when performing a tripping operation is expressed by the following equation (1). Given.
Ic / N = Ith, that is, Ic = N · Ith (1)

  In this embodiment, the threshold Ith of the trip control circuit 12 is set to a constant value, and the trip rated current Ic is set by the number N of turns of the secondary coil 14 of the current transformer 11. That is, when the rated current Ic is changed, the constant Ith of the trip control circuit 12 is maintained as it is, and the secondary number of the secondary coil 14 of the current transformer 11 is changed according to the expression (1) to change the secondary current Ic. The secondary current output from the coil 14 is not changed. At that time, the shape of the yoke 15 (such as the cross-sectional area of the magnetic path) is also changed as necessary so that the conversion characteristic of the current transformer 11 can maintain linearity at the rated current Ic after the change.

  Therefore, the linearity of the current transformer is maintained as compared with the method in which the electronic circuit (corresponding to the tripping control circuit 12) is replaced and the current transformer is used as it is as in Patent Document 1, and the circuit is interrupted by changing the rated current The accuracy of characteristics does not deteriorate. In addition, a current transformer that is less expensive than an electronic circuit is replaced, which is advantageous in terms of component costs.

  In this embodiment, the overcurrent detection unit 100 and the trip control unit 200 are housed in separate cases to form a unit. The unitized structure will be described below.

FIG. 2 is a diagram illustrating an assembly method of the overcurrent detection unit and the trip control unit.
The overcurrent detection unit 100 and the trip control unit 200 are configured by housing each component in an elastic material case. In the case of a three-phase power supply, the overcurrent detection unit 100 includes three current transformers 11a, 11b, and 11c and three load-side terminals 7a, 7b, and 7c, and the trip control unit 200 includes a trip control circuit. 12 and the tripping device 13 are stored. The outputs from the three current transformers 11a, 11b, and 11c are supplied to the trip control circuit 12, and the trip device 13 is activated when any one of the outputs becomes an overcurrent state.

  The hook portion 21 is provided in the case of the overcurrent detection unit 100, and the opening portion 22 is provided in the case of the trip control unit 200, and the hook portion 21 is engaged with the opening portion 22. 200 are combined and integrated. Note that the hook portion 21 and the opening portion 22 may have opposite configurations.

  Since the current transformer 11 is housed in the overcurrent detection unit 100 and the trip control circuit 12 is housed in the trip control unit 200, when the rated current Ic is changed, the trip control unit 200 remains as it is. The detection unit 100 may be replaced with one having another specification. Therefore, it becomes exchange by a unit unit and work becomes easy. Of course, when the trip control circuit 12 is replaced, the trip control unit 200 may be replaced with another one while the overcurrent detection unit 100 remains unchanged.

  As described above, according to the electronic circuit breaker of the present embodiment, the component parts can be easily assembled and replaced by unitizing the component parts into the overcurrent detection unit and the trip control unit. Moreover, it is possible to easily cope with a change in the rated current specification by replacing the overcurrent detection unit, and to provide a highly accurate electronic circuit breaker.

  The configuration of the present embodiment described above can also be applied to a mechanical circuit breaker. In other words, if the above-described overcurrent detection unit and tripping control unit are attached to the mechanical circuit breaker, the electronic circuit breaker of this embodiment can be used in combination. In that case, it is not only easy to assemble two units, it is easy to assemble, but many of the components of the mechanical circuit breaker can be shared. be able to.

1 ... power supply side terminal,
2, 4, 6 ... Electric circuit (conducting conductor),
3 ... Open / close contact,
7, 7a, 7b, 7c ... load side terminals,
8 ... Opening and closing device,
9 ... handle,
10: housing,
11, 11a, 11b, 11c ... current transformers,
12 ... Trip control circuit,
13 ... tripping device,
14 ... secondary coil,
15 ... York,
21 ... Hook part,
22 ... opening,
100: Overcurrent detection unit,
200: Trip control unit.

Claims (3)

In an electronic circuit breaker that detects an overcurrent flowing through an electric circuit and interrupts the electric circuit by a tripping operation,
A current transformer that converts the current flowing in the electric circuit into a secondary current and outputs it;
A trip control circuit that compares the value of the secondary current output from the current transformer with a threshold value and generates a trip signal when the value of the secondary current exceeds the threshold value;
A tripping device that operates the switchgear when the trip signal is received and interrupts the electric circuit;
An electronic circuit breaker comprising: the current transformer as a unit in an overcurrent detection unit; and the trip control circuit and the trip device as a trip control unit. The electronic circuit breaker according to claim 1,
When changing the value of the overcurrent at the time of interrupting the electric circuit, the threshold set in the trip control circuit is maintained as it is, and the number of turns of the secondary coil in the current transformer is changed, whereby the current transformer An electronic circuit breaker characterized by not changing the secondary current output from the circuit. The electronic circuit breaker according to claim 1 or 2,
The overcurrent detection unit and the tripping control unit are configured to be housed in elastic material cases, respectively, and the units are integrated by engaging openings and hooking portions provided in the cases. A featured electronic circuit breaker.

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