Over current protection system of the breaker and its operating method

Abstract

The invention relates to current foldback circuit of breaker that comprises: SCM circuit, current transformer, A / D transformation circuit, and trip drive circuit and trip executable unit; current detecting output end of the current transformer is connected with the detecting signal input end via the A / D transformation circuit; the trip control output end of the SCM circuit is connected with the trip executable unit via the trip drive circuit; alarm circuit is set on the alarm signal output end of the SCM circuit; OFF selecting unit is set at the function selecting input end of the SCM circuit. The breaker of the invention can fulfill the operating requirements of special occasion; it can assure during the fire-fighting, even if the fire pump is overloaded, the fire pump will not stop working to affect emergency fire-fighting.

Description

technical field [0001] The invention relates to an overcurrent protection system of a circuit breaker and a working method thereof. Background technique [0002] The plastic case of an ordinary plastic case circuit breaker is composed of a base and a cover, and all parts are installed in the plastic base. A circuit breaker generally includes functional units such as a contact system, an arc extinguishing system, an operating mechanism and a free tripping mechanism, an overcurrent protection system, a short circuit protection system, an insulating casing, and an operating handle. The contact movement makes the circuit breaker turn on and off, and realizes the control of the electric energy flow of the electric line; through the sensing of the current heat and magnetic effect, the electric line is protected against overload, short circuit and other faults. [0003] Circuit breakers have a wide range of uses. It is not only used for main lines, branch circuits, circuit ends, e...

AI Technical Summary

Problems solved by technology

[0006] The disadvantage of the above-mentioned prior art is that the circuit breaker cannot meet the requirements for the control and protection of important fire-fighting equipment, and does not meet the requirements of the circuit breaker for the main circuit of important fire-fighting equipment in the GB50054-95 "Code for Design of Low-Voltage Power Distribution" , that is, during the use of the fire pump, even if there is an overload phenomenon, the power of the fire pump cannot be cut off, which will seriously affect the emergency fire and disaster relief.

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