JPH04267028A - Overcurrent trip device for circuit breaker - Google Patents

Abstract

PURPOSE:To simplify the structure of an electronic overcurrent trip device. CONSTITUTION:Printed boards 11A, 11B mounted with electronic circuits are directly supported by a current transformer 1 detecting the overcurrent state of a circuit breaker as a current signal. A support projection 16a is formed integrally with the fastening plate 16 of a laminated iron core 9, and it is pressed into the printed board 11A and welded to fix the printed board 11A. A mold resin base which has been used to support the current transformer 1 and the printed boards 11A, 11B is omitted, the number of parts is reduced, and the man-hours for screwing the current transformer 1 to the base are decreased.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention monitors the current flowing through a circuit breaker such as a molded circuit breaker via a current transformer, and when an overcurrent condition occurs, outputs a tripping signal to circuit the circuit breaker. The present invention relates to an electronic overcurrent tripping device that operates to interrupt a circuit breaker.

0002

2. Description of the Related Art FIG. 5 schematically shows the structure of a circuit breaker equipped with an electronic overcurrent tripping device. As shown in the figure, electronic overcurrent tripping devices are generally divided into current transformers 1 and 1.
, an electronic circuit 2 and a trip coil unit 3. A current transformer 1 whose primary conductor is a main conductor 4 in the circuit breaker detects the current flowing through the circuit breaker as shown by the arrow, and outputs a current signal to the electronic circuit 2. The electronic circuit 2 constantly monitors this current signal, and when determining an overcurrent state, outputs a tripping signal to the trip coil unit 3 with a delay time corresponding to the magnitude of the current. Trip coil unit 3
When a tripping signal is input, the plunger 5 is projected to mechanically act on the opening/closing mechanism 6 of the circuit breaker, unlocking the tripping mechanism and opening the movable contact 7 as shown in the figure. .

FIG. 6 is a side view showing a specific configuration of a conventional overcurrent tripping device. In the figure, reference numeral 8 denotes a box-shaped base made of molded resin. A trip coil unit 3 is held on this base 8, a current transformer 1 is attached to the upper end of a laminated core 9 with screws 10, and an electronic circuit is also mounted on the base 8. A printed board 11 on which is mounted is attached with screws 12 or the like. A secondary winding 13 is wound around the laminated core 9, and its output lead wire 13a is soldered to the input terminal of the printed board 11. In this overcurrent tripping device, a base 8 is fastened and fixed to the case of the circuit breaker with screws (not shown).

0004

However, such conventional overcurrent tripping devices have the following problems. (1) Since the current transformer 1 and the printed board 11 are separately attached to the base 8 with screws, it takes time and effort to tighten these screws. (2) The lead wire 13a from the current transformer 1 is connected to the printed board 11
The lead wire 13 is wired and soldered to
Since a is quite long, it is necessary to fix it in the middle, which takes time and effort, and there is a risk that the soldered part will loosen due to vibration due to the impact when the circuit breaker is opened and closed. (3) The overcurrent tripping device is fixed to the case with screws, but tightening the screws is also time-consuming. The present invention is intended to solve these problems, and aims to provide an overcurrent tripping device for a circuit breaker that requires fewer manufacturing steps and is highly reliable.

[0005]

SUMMARY OF THE INVENTION The present invention attempts to achieve the above object by using the current transformer itself as a support base for a printed board. That is, support protrusions are integrally formed on the clamping plates that sandwich the laminated iron core of the current transformer, and the printed board on which the electronic circuit is mounted is supported by the current transformer via the support protrusions. At that time, the support protrusion of the current transformer clamping plate is directly connected to the input terminal of the electronic circuit on the printed board, and the lead wire of the secondary winding of the current transformer is connected to this clamping plate. By inputting the current signal of the device to the electronic circuit through its clamping plate, processing of the lead wire is facilitated. Further, by integrally forming a mounting leg on the clamping plate of the current transformer and fixing the current transformer to the case of the circuit breaker via the mounting leg, the overcurrent tripping device can be easily fixed.

[0006]

[Function] By using the current transformer as a support base and supporting the printed board on this base, the base on which the current transformer and printed board were conventionally attached is no longer required, reducing the number of parts, and the current transformer relative to the base. Eliminates the need to tighten screws on containers and printed boards. The printed board can be easily fixed to the current transformer by press-fitting the support protrusion, which is integrated with the clamping plate of the current transformer, into the printed board and soldering it. Note that the trip coil unit, which was conventionally attached to the base, can be supported by the cover of the circuit breaker.

When fixing the printed board to the current transformer, the support protrusion of the current transformer clamping plate is connected to the input terminal of the electronic circuit on the printed board, and the lead wire of the secondary winding of the current transformer is connected to the input terminal of the electronic circuit on the printed board. If the current signal of the current transformer is connected to this clamping plate and the current signal of the current transformer is inputted to the electronic circuit by using the clamping plate as an output terminal, the length of the lead wire becomes correspondingly shorter and its processing becomes easier. If the mounting legs are integrally formed on the clamping plate of the current transformer, the current transformer supporting the printed board can be easily fixed by press-fitting the mounting legs into the case of the circuit breaker.

[0008]

Embodiments Hereinafter, embodiments of the present invention will be described based on FIGS. 1 to 4. Note that the same reference numerals are used for parts corresponding to those in the conventional example. First, FIG. 4 is a sectional view of a main part of a circuit breaker incorporating an overcurrent tripping device. In the figure, among printed boards 11 (11A to 11C), printed boards 11A and 11B are supported by a current transformer 1, and the current transformer 1 is fixed to a case 14 of a circuit breaker. The trip coil unit 3 is attached to the cover 15 of the circuit breaker, and the printed board 11C is connected to the trip coil unit 3.
is attached to. Printed boards 11B and 11C are connected via a connector (not shown).

FIG. 1 is an enlarged perspective view of the main parts of the overcurrent tripping device. The laminated iron core 9 of the current transformer 1 is sandwiched between rectangular tightening plates 16 made of iron plates on both the left and right sides, and is tightened at four locations with screws 17. Tightening plate 16 and laminated iron core 9
The space between them is electrically insulated by an insulating sheet (not shown), and the space between the tightening plate 16 and the screw 17 is also insulated by an insulating tube (not shown). A prismatic support protrusion 16a is integrally formed at the upper end of each clamping plate 16, and a mounting leg 16b having an engaging claw at the tip is integrally formed at the lower end. Further, on one side of each tightening plate 16, there are two upper and lower parts.
Terminal claws 16c are cut and raised at the locations.

A secondary winding 13 is wound on the laminated iron core 9 by dividing it into upper and lower halves, and the lead wire 13a at the end of the upper winding and the lead wire 13a at the beginning of the lower winding are shown in the figure. The upper and lower terminal claws 16c of the front left clamping plate 16 are soldered to each other, and the upper and lower windings are connected to each other via this clamping plate 16. Also, the lead wire 13a at the beginning of winding of the upper winding is attached to the upper terminal claw 1 of the clamping plate 16 on the front right side of the figure.
6c, and the lead wire 13a at the end of the lower winding is soldered to the lower terminal claw 16c of the clamping plate 16 on the far right side of the figure, and these clamping plates 16 are connected to the current transformer 2.
This is the output terminal.

On the other hand, the printed board 11B is provided with a cutout 18 for escaping the secondary winding 13 of the current transformer 1 of each phase, and mounting holes 19 are formed on both sides of the cutout in alignment with the support projections 16a. This printed board 11B is fitted into the current transformer 1 from above so as to be in close contact with the laminated iron core 9, and is soldered to the support protrusion 16a press-fitted into the mounting hole 19. here,
An input terminal of an electronic circuit is wired to a mounting hole 19 into which a support protrusion 16a of a clamping plate 16 serving as an output terminal of the current transformer 1 is press-fitted. Therefore, the output of the current transformer 1 is transmitted from the lead wire 13a to the printed board 11B via the clamping plate 16.
It is input to the electronic circuit above.

The printed board 11A is also provided with a cutout for the secondary winding 13 and a mounting hole into which the mounting leg 16b is press-fitted. It is fitted into the container 1 from below. In the current transformer 1 with the printed boards 11A and 11B attached, the mounting leg 16b is press-fitted into the fixing hole 21 provided in the fixing part 20 of the case 14, and the claw at the tip engages with the fixing part 20. Fixed. Since the printed board 11A is held between the current transformer 1 and the fixed part 20, soldering to the mounting leg 16b is not necessary.

FIGS. 2 and 3 show another embodiment of the means for fixing the printed board to the current transformer. FIG. 2 shows wire wrapping, in which a wire 22 is tightly wrapped so as to bite into a support protrusion 11a press-fitted into the printed board 11B, thereby fixing the printed board 11B. In addition, in FIG. 3, the connector 2 is attached to the printed board 11B.
3 is fixed, and the support protrusion 16a is press-fitted into the support protrusion 16a for fixation.

In the configuration described above, the conventional base is eliminated and the printed boards 11A and 11B are supported by the current transformer 1, and moreover, they are supported by the support protrusion 16 integrated with the clamping plate 16.
Since they are connected via a, the number of man-hours is reduced compared to screw tightening, the number of parts is reduced, and the external dimensions are compact. Furthermore, since the clamping plate 16 is used as an output terminal, the lead wire 13a is shortened, making it easier to dispose of it, and reducing the risk of loosening of the soldered portion. Further, since the current transformer 2 is fixed by press-fitting the mounting leg 16b integral with the clamping plate 16 into the case 14, there is no need for screw tightening or a separate mounting member.

[0015]

According to the present invention, there is no need for a base for supporting a current transformer or a printed board, so the number of parts is reduced and the number of man-hours required for tightening screws is also reduced. In this case, the wiring process is facilitated by using the clamping plate of the current transformer as an output terminal for inputting the secondary output to the electronic circuit. Furthermore, the structure is further simplified by fixing the current transformer to the case via the mounting leg that is integrated with the clamping plate.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of essential parts of an embodiment of the invention.

FIG. 2 is an exploded perspective view of main parts showing another embodiment of the invention.

FIG. 3 is an exploded perspective view of a main part showing still another embodiment of the invention.

FIG. 4 is a longitudinal sectional view of a main part of the circuit breaker equipped with the overcurrent tripping device of FIG. 1;

FIG. 5 is a vertical cross-sectional view schematically showing the general configuration of a circuit breaker equipped with an electronic overcurrent tripping device.

FIG. 6 is a side view of a conventional example.

[Explanation of symbols]

1 Current transformer 9 Laminated iron core 11 Printed board 13 Secondary winding 13a Lead wire 16 Tightening plate 16a Support protrusion 16b Mounting leg

Claims (3)

[Claims] 1. A current transformer that detects the current flowing through a circuit breaker as a current signal, and an electronic circuit that monitors the magnitude of the current signal and outputs a trip signal when an overcurrent condition is determined. In the overcurrent tripping device for a circuit breaker equipped with a current transformer, a supporting protrusion is integrally formed on the clamping plate that sandwiches the laminated core of the current transformer,
An overcurrent tripping device for a circuit breaker, characterized in that a printed board carrying an electronic circuit is supported by the current transformer via the support protrusion. 2. The support protrusion of the clamping plate is directly connected to the input terminal of the electronic circuit on the printed board, and the lead wire of the secondary winding of the current transformer is connected to the clamping plate. 2. The overcurrent tripping device for a circuit breaker according to claim 1, wherein a current signal of the circuit breaker is inputted to the electronic circuit via the clamping plate. 3. The circuit breaker according to claim 1 or 2, wherein a mounting leg is integrally formed on the clamping plate, and the current transformer is fixed to the case of the circuit breaker via the mounting leg. Overcurrent trip device for equipment.