AC circuit breaker electronic backup protection device

Abstract

The invention relates to an electronic type backup protection device for an AC (alternating current) circuit breaker. The electronic type backup protection device comprises input terminals of three current transformers, ten resistors and electrolytic capacitors of three rectifier bridges, a voltage-regulator tube, operational amplifiers AR1 and AR2, an audion Q1 and an executing magnetic flux M1; when the current which passes through any phase or more than one phase in the three current transformers is greater than a short-circuit current value, the induced current generates a negative signal at non-GND (ground) ends of the three resistors through the three resistors after being rectified by the three rectifier bridges, enters into the operational amplifier AR1 through another resistor, is amplified by means of inverse proportion, and is connected with a positive-phase input end of the operational amplifier AR2 through an output end of the operational amplifier AR1; and the amplitude value of the signal is greater than a reference voltage value between any two resistors, the operational amplifier AR2 outputs a high voltage, and the executing magnetic flux drives the circuit breaker to be turned off. The electronic type backup protection device provided by the invention is simple in circuit structure, high in stability, lower in cost, and reliable in the short-circuit protection function, so that the short-circuit turning-off protection actuation time of an electronic type intelligent circuit breaker can be greatly improved.

Description

technical field [0001] The invention belongs to an AC circuit current protection circuit, in particular to an electronic backup protection device for an AC circuit breaker. Background technique [0002] With the rapid and extensive application of electronic technology in various fields, the current protectors of AC circuits have also evolved from magnetic thermal circuit breakers to electronic intelligent circuit breakers. However, there is a common phenomenon at present: electronic intelligent circuit breakers are indeed much better than magnetothermal circuit breakers in terms of protection accuracy, but in terms of breaking protection speed of short-circuit current, electronic intelligent circuit breakers are generally slower for magnetic thermal circuit breakers. The main reason is that the current signal collected in the electronic intelligent circuit breaker comes from the current transformer. This signal needs to be sampled and processed by the single-chip microcompu...

AI Technical Summary

Problems solved by technology

Because the short-circuit breaking protection time is greatly related to the breaking capacity of the circuit breaker, many electronic intelligent circuit breakers cannot completely break away from the limitation of magnetic-thermal protection, and often only replace thermal protection, but magnetic protection must be left.

Some circuit breakers have also added corresponding electronic backup protection circuits in their design, but their structures are complex, and they use more electronic components. If there are more components, their stability will be relatively low, resulting in insufficient protection accuracy.

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