Thermomagnetic tripper of breaker

Abstract

The invention relates to a thermomagnetic tripper applied to a small-size low-pressure breaker, comprising a bracket 1 as well as a short-circuit tripping system and an overload tripping system respectively arranged at both sides of a bracket plate. An electromagnetic coil 5 of the short-circuit tripping system is wound on a columnar static iron core 4; a short-circuit current passes by the electromagnetic coil 5 and generates a magnetic field together with the static iron core 4; in case of short circuit, a movable armature 2 overcomes a reaction spring 3 to act under the action of magnetic field force; the overload tripping system comprises a heat element 12 and a bimetallic sheet 6 which are stacked on a lug boss 16 at the bottom of the bracket 1; and the heat element 12 and / or a bimetallic sheet 6 are / is connected in series with a circuit by soft junctions 10 and 15 to sense an overload signal and also connected in series with a resistance sheet 13 to increase heat productivity. The invention structurally adopts the two independent and mutual non-interfering tripping systems to improve the operation stability and ensure that the breaker cuts off a failure current stably and reliably under smaller short-circuit current and overload current.

Description

technical field [0001] The invention relates to a tripping device for a modular control and protection switch, in particular to a thermomagnetic tripping device for a low-voltage small current circuit breaker. Background technique [0002] The existing low-voltage circuit breaker module generally includes parts such as an arc extinguishing device, a contact system, an operating mechanism, and a tripping device. The release device, especially the overcurrent release, is an important part of the circuit breaker. Its function is to trigger the release of the circuit breaker's operating mechanism when the circuit breaker is overloaded or short-circuited in the circuit and electrical equipment. , to cut off the main circuit to realize the protection of lines and electrical equipment. At present, the tripping devices of circuit breakers mainly adopt two types: electromagnetic tripping device and thermal magnetic tripping device. [0003] The first type of electromagnetic release...

AI Technical Summary

Problems solved by technology

As disclosed in Chinese patents CN01132307.8 and CN200720073464.0, the structure of the existing thermal-magnetic trippers has the disadvantage that: the existing trippers generally form a magnetic conduction circuit by a U-shaped yoke and an armature. When the short-circuit current When it is less than 500A, the U-shaped magnetic yoke shows the problem that it cannot generate a large enough magnetic field to attract the movable armature, resulting in the inability to cut off the current to protect the power supply equipment, and the small overload current will also have a similar effect on the existing thermal magnetic release Impact

Especially for circuit breakers with relatively small current specifications, such as circuit breakers with a rated current below 50A, the existing thermal magnetic release cannot meet the requirements of power distribution and electric protection for its short-circuit current

In addition, the working areas of the thermal trip system and the magnetic trip system of the existing design are mixed, overlapped, or even share some components, which will cause the two systems to interfere with each other and affect the stability of the equipment

[0005] The release shared the tripping element or the mutual interference between the two systems of the thermal magnetic release will cause the following problems: 1. When the short-circuit current of the product does not operate or starts early, the adjustment of the product release will lead to overload protection early or immobile

2. When there is no action or early action during overload and short circuit adjustment, the adjustment of the product release will cause early action or immobility of the short circuit protection

This situation will cause the product quality to fail to meet the requirements of national standards, causing certain safety hazards to users

In actual production, in order to ensure that the overload setting value meets the standard requirements, the short-circuit protection usually only operates within 0.2s according to the (1+20%) short-circuit current, and the (1-20%) short-circuit current requires within 0.2s No adjustment is made when the internal motion is not in motion

This will cause the product to act when the short-circuit current in the line has not reached the product’s set current, cutting off the line current will cause certain economic losses to the user

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