JPH0432121A - Molded-case circuit breaker - Google Patents

Abstract

PURPOSE:To simply compose a molded-case circuit breaker having a high func tion, a tripping operation characteristic of high breaking capacity and high reliability by using together overcurrent tripping devices - mechanical and electrical types. CONSTITUTION:When an overcurrent flows through conductors 4 and 41, an electronic circuit sends out tripping instructions to a trip coil mechanism 10 with a delay time according to the currents to excite a trip coil 14 so that a magnetic flux in the reverse direction to a permanent magnet 17 is generated, a movable iron core 19 is detached from a fixed iron core 13 due to the force of a driving spring 25 and therewith a lever 24 turns clockwise. The lever 24 attracts a trip cross bar 11a to tear down a locking mechanism of a switching mechanism part 11 to dissociate a movable contact shoe. In a current region exceeding rated breaking capacity, a movable iron piece 8 of a mechanical overcurrent tripping device is momentarily attracted by a fixed magnet 6 resisting to a reset spring 9 to push a trip cross bar 11 to make the switching mechanism part 11 to perform dissociation action.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a molded case circuit breaker, and more particularly to a molded case circuit breaker with improved tripping characteristics.

[Conventional technology]

There are two types of overcurrent release devices incorporated into molded circuit breakers: mechanical and electronic. Mechanical overcurrent tripping devices use a bimetal that thermally detects current in order to achieve a long-time tripping characteristic that causes tripping after a predetermined delay time when a relatively small overcurrent flows. In order to achieve an instantaneous release characteristic that causes immediate tripping when a large current such as a short-circuit current flows, an electromagnet is used that detects the magnetic field caused by the current and attracts the movable iron piece. Furthermore, a separate movable iron piece with a gear mechanism interposed therebetween is used in order to realize a short-time release characteristic that facilitates operational coordination with other overcurrent protection devices. On the other hand, electronic overcurrent tripping devices constantly monitor the current signal detected by a current transformer using an electronic circuit, and if an overcurrent condition is determined, a delay time corresponding to the magnitude of the current is set. It outputs a trip signal to the trip coil.

[Problem to be solved by the invention]

By the way, it is technically difficult to configure the mechanical overcurrent tripping device so that operating characteristics such as operating current and delay time can be adjusted, and the gear mechanism to obtain short-time characteristics requires a large volume. Therefore, there is a drawback that the outer diameter of the molded circuit breaker becomes large. On the other hand, although electronic overcurrent tripping devices can easily realize the ability to adjust various operating characteristics, they have the problem that the instantaneous tripping time is longer than that of mechanical overcurrent tripping devices, and the rated breaking capacity is small. Furthermore,
Electronic overcurrent tripping devices use more parts than mechanical ones, so there is also the problem that they are less reliable. therefore,
Molded case circuit breakers with either mechanical or electronic overcurrent disconnect devices are bound to have some of the problems associated with each type. This invention attempts to solve the above problem by combining a molded case circuit breaker equipped with a mechanical overcurrent disconnection device (hereinafter referred to as a mechanical molded circuit breaker) with an electronic overcurrent disconnection device. The object of the present invention is to provide a molded case circuit breaker.

[Means for Solving the Problems] This invention is based on a molded circuit breaker equipped with a mechanical overcurrent disconnection device, and by attaching a unitized electronic overcurrent disconnection device thereto. This aims to achieve the above objectives. That is, the present invention provides an electronic type that cooperates with the mechanical overcurrent tripping device at a load side terminal portion of a molded circuit breaker equipped with a mechanical overcurrent tripping device having a bimetal and an electromagnet as an overcurrent detection section. The current transformer, electronic circuit, and through conductor of the overcurrent tripping device are housed and installed in a special case, and the trip coil mechanism of the electronic overcurrent tripping device is connected to the wiring along with the mechanical overcurrent tripping device. shall be located within the body of the circuit breaker.

[For use]

The parts of the electronic overcurrent trip device other than the trip coil mechanism, that is, the current transformer, electronic circuit, and through conductor, are housed in a special case and assembled into a unit, which is attached to the load side terminal of a mechanical circuit breaker. However, the trip coil mechanism is placed in the circuit breaker case together with the mechanical overcurrent trip device. As a result, a molded case circuit breaker that uses both a mechanical and electronic overcurrent disconnect device can be easily produced using a mechanical molded case circuit breaker. In combination type molded circuit breakers, short-time tripping characteristics and adjustable operating characteristics are provided by an electronic overcurrent tripping device, while instantaneous tripping characteristics are provided by a mechanical overcurrent tripping device. Achieves higher rated breaking capacity than electronic type. In addition, by equipping the mechanical overcurrent tripping device with a bimetal that has a long-time release characteristic that lasts longer than the electronic overcurrent tripping device, it is possible to prevent the electronic overcurrent tripping device from malfunctioning and become inoperable. This ensures protection of the wires even in the event of

【Example】

Hereinafter, the present invention will be explained in detail based on FIGS. 1 to 3. Here, Fig. 1 (A) is a schematic vertical sectional view of the main parts of the molded circuit breaker, Fig. 2 (B) is its plan view, and Fig. 2 is Fig. 1 (A).
Figure 3 (A) is an enlarged vertical cross-sectional view of the trip coil mechanism in Figure 3 (A) is a diagram of the operating characteristics of the mechanical current release device;
) is an operating characteristic diagram of the electronic overcurrent tripping device, and (C) is an operating characteristic diagram when both are used together. First, in FIG. 1, reference numeral 1 denotes a circuit breaker body which is used alone as a mechanical circuit breaker, and various components are housed in an outer box consisting of a case 2 and a cover 3 made of molded resin. Reference numeral 4 denotes a load-side conductor whose one end serves as a load-side terminal plate, and the other end is connected to a movable contact (not shown) via a flexible conductor. 5 is a bimetal of a mechanical overcurrent tripping device, and 6 is a fixed magnet, which are fixed together to the conductor 4 by a rivet 7. 8 is a movable iron piece placed opposite to the fixed magnet 6, and 9 is its return spring. Reference numeral 10 denotes a magnetically held type trip coil mechanism of an electronic overcurrent tripping device, in which a bimetal 5 and a movable iron piece of a mechanical overcurrent tripping device are sandwiched between a trip cross spar 11a that constitutes a part of the opening/closing mechanism section 11. It is located on the opposite side of 8. Here, the configuration of the trip coil mechanism 10 will be explained with reference to the longitudinal sectional view of FIG. 2. In the figure, 12 is a U-shaped yoke, 13 is a fixed core fixed to the yoke, 14 is a trip coil fitted to the outside of the fixed core 13 via a cylinder 15, 16 is a shunt fitted to the cylinder 15, and 17 18 is a pair of upper and lower permanent magnets arranged adjacent to the trip coil 14 on the outside of the shunt 16; 18 is a yoke piece that is coupled across both legs of the yoke 12 and holds down the shunt 16 and the permanent magnet 17; 19 is a cylinder 1
5, a movable core 20 is fixed to the movable core 19 and the tip thereof loosely passes through the fixed core 13 and projects outside the yoke 12; 21 is a movable pin 20;
This is a return spring installed between the head of the yoke 12 and the yoke 12. The yoke 12 is held by a box-shaped base 22 made of resin molding as shown in the figure, and the movable pin 20 protruding from the yoke 12 is
One end faces the midsection 24a of the lever 24, which is rotatably supported by the base 22 via a pin 23. The lever 24 is constantly subjected to a rotational force clockwise in the figure by a drive spring 25, which is a torsion spring attached to the bottle 23. When the trip coil 14 is not excited, the movable core 19 is attracted to the fixed core 13 by the magnetic flux of the permanent magnet 17 as shown in the figure, and the movable pin 20 resists the drive spring 25 to restrain the lever 24 at the position shown in the figure. ing. The trip coil mechanism 10 having such a configuration is constructed as shown in FIG. As shown, it is detachably attached to the side of the opening/closing mechanism section 11, and is fixed by being pressed down from above by the cover 3. When the lever 24 is attached to the case 2, the tip of the lever 24 restrained by the movable pin 20 is connected to the trip crossper 1.
It is arranged to face 1a with a predetermined distance therebetween. On the other hand, 26 is a special case for an electronic overcurrent tripping device consisting of a case body 27 and a cover 28, and a printed board 29
A current transformer 30 mounted on the current transformer 30 and a through conductor 31 passing through the current transformer 30
, printed boards 32 and 33 equipped with an electronic circuit for monitoring the current flowing through the through conductor 31 via the current transformer 30 are accommodated. The through conductor 31 is fastened to the case body 27 from the back side with a screw 34, and one end 31a becomes a connection end with the load side terminal plate 4a of the circuit breaker body 1, and the other end 31b becomes a new load side terminal plate. There is. The main body 27 of the case 26 is, as shown in FIG. 1(B),
The retaining protrusion 27a having a bulge at the tip is fitted into the groove 2a of the same shape formed between the phases of the case 2 to be attached to the circuit breaker main body l, and the connecting end 31a of the through conductor 31 is connected to the back side of the case 2 with a screw 35. It is fastened to the terminal plate 4a from the side. Note that the groove 2a is used as a standard equipment for mounting an interphase barrier. Cover 28 of case 26
is fastened to the case body 27 from the front side with screws 36 and from the back side of the case 2 with screws 37, respectively. The lead wire 38 drawn out from the trip coil mechanism 10 and the lead wire 39 drawn out from the electronic circuit in the case 26 are connected to each other by a pair of male and female connectors 40 and 41. Here, the third section showing the relationship between the magnitude of overcurrent and operating time is
The operating characteristics shown in the figure will be explained. FIG. 3(A) shows the operating characteristics of the mechanical overcurrent tripping device, which consists of a long-time tripping characteristic by the bimetal 9 and an instantaneous tripping characteristic by the electromagnet (fixed magnet 6 and movable iron piece 8). same(
B) is the operating characteristic of the electronic overcurrent tripping device, which consists of long-time disconnection characteristics, short-time disconnection characteristics, and instantaneous tripping characteristics, and point R indicates the rated breaking capacity. Further, Δ11 is an adjustable range of the short-time tripping current, and ΔI2 is an adjustable range of the instantaneous tripping current. (C) is the operating characteristic of the molded case circuit breaker shown in Figure 1 that uses both mechanical and electronic types; below the rated breaking capacity, the tripping characteristics of the electronic overcurrent tripping device are used; Utilizes the instantaneous trip characteristics of a mechanical overcurrent trip device. With these operating characteristics, when the current flowing through the conductors 4 and 31 becomes overcurrent, the electronic circuit that detects this through the current transformer 3° causes the trip coil mechanism 1o to trip with a delay time depending on the current. Send command to trip coil 14
Excite. When the trip coil 14 is excited, it generates a magnetic flux in the opposite direction to the permanent magnet 17, so the movable iron core 19 is separated from the fixed iron core 13 by the force of the drive spring 25, and the lever 24 rotates clockwise accordingly. . This lever 24 pulls the trip cross spar 11a to the left in the figure, breaks down the locking mechanism of the opening/closing mechanism section 11, and opens a movable contact (not shown). As already mentioned, tripping is performed by the electronic overcurrent tripping device below the rated breaking capacity, but in the current range exceeding that, the movable iron piece 8 of the mechanical overcurrent tripping device resists the return spring 9. is instantly attracted to the fixed magnet 6,
The trip cross spar 11a is pushed to open and close the opening/closing mechanism 11. In addition, when the electronic overcurrent trip device becomes inoperable, the trip cross spar 11a is pushed by the curvature of the bimetal 5 heated by the heat generated by the conductor 4 due to Joule heat, and the trip cross spar 11a is pushed as shown in FIG. A tripping operation with the characteristics shown by the broken line is performed. As described above, according to the illustrated configuration, the long-time and short-time release characteristics and the ability to adjust each operating characteristic are obtained by the electronic overcurrent trip device, and the instantaneous release characteristics are obtained by the mechanical overcurrent trip device. As a result, it is possible to construct a molded circuit breaker with a large breaking capacity while having excellent adjustable functions, and also has long operating time characteristics even if the electronic overcurrent trip device fails and becomes inoperable. It can be covered with a bimetal with Moreover, there is no need to specially produce a illustrated hardwired circuit breaker equipped with both types of overcurrent release devices; instead, a mechanical hardwired circuit breaker is used as the circuit breaker main body 1, and the trip coil mechanism 10 is fitted into the case 2 to load the circuit breaker. It can be easily constructed by simply attaching the dedicated case 26 to the side terminal portion.

【Effect of the invention】

According to the present invention, a wiring disconnection with high reliability is achieved, which uses both mechanical and electronic overcurrent disconnection devices, and has high functionality and tripping operation characteristics with high breaking capacity by taking advantage of the advantages of each. It becomes possible to easily configure the container.

[Brief explanation of the drawing]

FIG. 1(A) is a longitudinal cross-sectional view of a main part of an embodiment of the present invention.
Figure (B) is its plan view, Figure 2 is an enlarged vertical sectional view of the trip coil mechanism in Figure 1 (A), Figure 3 (A) is an operating characteristic diagram of the mechanical overcurrent trip device, and Figure 3 Figure (B) is a diagram of the operation of the electronic overcurrent tripping device, Figure 3 (C)
2 is an operating characteristic diagram of the molded circuit breaker of FIG. 1. FIG. 1... Breaker body, 2... Case, 3... Cover 4... Load side conductor, 5... Bimetal, 6...
Fixed magnet, 8... Movable iron piece, 10... Trip coil mechanism, 11... Opening/closing mechanism section, lla... Trip cross spar 26... Special case, 30... Current transformer, 31... ...Through conductor.

Claims (1)

[Claims] 1) Electronic overcurrent tripping that is coordinated with the mechanical overcurrent tripping device on the load side terminal section of a molded circuit breaker equipped with a mechanical overcurrent tripping device having a bimetal and an electromagnet as an overcurrent detection section. The current transformer, electronic circuit, and through conductor of the device are housed and installed in a special case, and the trip coil mechanism of this electronic overcurrent tripping device is installed in the main body of the molded case circuit breaker. A hardwired circuit breaker characterized by being placed together with the device.