Short circuit time delay tripping mechanism of selectively protecting micro breaker

Abstract

The invention discloses a short circuit time delay tripping mechanism of selectively protecting micro breaker, belonging to the manufacturing technology field of breaker, and the short circuit time delay tripping mechanism of selectively protecting micro breaker comprises an electromagnetism mechanism, a contact connection rod mechanism and main contact assembled together, a bearing torsional spring blocking the movement of the contact connection rod mechanism, the electromagnetism mechanism comprises a movable iron core, a static iron core, an electromagnetism coil, a motion mandril, an outer yoke support shelf, a load boundary plate, a first spring, a second spring, V-shaped plane groove, a bearing torsional spring, a bearing torsional spring fixing shelf, a first connection shaft, a second connection shaft and a third connection shaft; the load boundary plate is combined with the first spring or the second spring and matched with the V-shaped plane groove of the bearing torsional spring in a motion mode for solving the problem that the short circuit time delay tripping action is inaccurate below E,CS character of the electromagnetism mechanism.

Description

technical field [0001] The invention relates to a tripping mechanism, in particular to a short-time-delay tripping mechanism of a selective protection miniature circuit breaker, belonging to the technical field of circuit breaker manufacture. Background technique [0002] my country is building a smart grid with the main characteristics of "strong, interactive, self-healing, high-quality, compatible, and coordinated", which puts forward higher requirements for the safety, reliability, and continuity of electricity consumption. In the terminal power distribution system, cascaded miniature circuit breakers (MCB, Miniature Circuit Breaker) will trip over the level when a short-circuit fault occurs, which greatly affects the continuity, stability and reliability of the power supply system. Selective protection of Miniature Circuit Breaker (SMCB, Selective protection of Miniature Circuit Breaker) is a new type of low-voltage switching device developed to overcome this problem. It...

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Problems solved by technology

[0004] However, at present, the design of SMCB's electromagnetic mechanism relies more on the experience of engineers, through prototype production and a large number of tests to determine the scheme, resulting in the inability to accurately determine the electromagnetic force between the moving and static iron cores, the connection between the moving ejector rod and the contact link mechanism. Whether the frictional force of the end surface of the rod plane support and the torsion force of the load-bearing torsion spring can achieve the optimal mechanical coordination characteristics, which will eventually lead to short-circuit delay under the E characteristic of the short-circuit current when the short-circuit current is 5In (rated current). When it is 6.25In, the electromagnetic mechanism acts immediately, C S Under the characteristics, the electromagnetic mechanism does not operate when the short-circuit current is 6.5In, and the protection characteristic of immediate action fails when the short-circuit current is 10In, which seriously affects the overall working performance of the SMCB.

[0005] The existing selective protection miniature circuit breaker electromagnetic mechanism has the following disadvantages: when a short-circuit current occurs in the power distribution system, the electromagnetic mechanism cannot be precisely controlled to reach E or C S No action at 5In or 6.5In (rated current) under the characteristic, 6.25In or 10In (rated current) must be opened and the maximum opening distance can be reached, and there should be a holding effect under a small electromagnetic force

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