CPLD-based protection relay in AC and open-phase protection system

Abstract

The invention provides a CPLD-based protection relay in AC (Alternating Current) and an open-phase protection system. The open-phase protection system comprises a signal acquisition module, a CPLD logic processing module and a thyristor control protection module, wherein the signal acquisition module converts an AC signal and a state into a processible weak current signal, and transfers the weak current signal to a CPLD logic processing module; the CPLD logic processing module can judge the state of AC through a collected signal, output a corresponding signal to the thyristor control protection module according to the current state; once an open phase is detected, single thyristor is closed immediately to protect the relay, then the relay is disconnected, a pulse string is stopped immediately, unidirectional silicon is disconnected to protect the entire circuit and load. The system solves the problem of electric arc generated when the relay is closed or opened, is flexible in use, and can play a protection role on the entire circuit and load.

Description

technical field [0001] The invention relates to a CPLD-based alternating current protection relay and a phase loss protection system thereof. Background technique [0002] With the development and maturity of AC technology, the use of AC has penetrated into every family and every factory, playing an indispensable role. In alternating current, relays are usually introduced as objects to control the on-off of circuits. The installation of relays used in some power grids is complicated, and once damaged, it will consume a lot of manpower and material resources to repair. At the same time, when the relay is closed or disconnected, we can often see sparks, which is what we usually call arcs. The appearance of electric sparks will cause great damage: ablation of contacts, generation of electromagnetic interference, increased loss, Reducing over-voltage, etc., not only threatens the safety of the entire circuit, but also causes some damage to the relay itself to a certain extent, ...

AI Technical Summary

Problems solved by technology

In alternating current, relays are usually introduced as objects to control circuit on and off. The installation of relays used in some power grids is complicated, and once damaged, it will consume a lot of manpower and material resources to repair.

At the same time, when the relay is closed or disconnected, we can often see sparks, which is what we usually call arcs. The appearance of electric sparks will cause great damage: ablation of contacts, generation of electromagnetic interference, increased loss, Reduce the over-voltage, etc., which not only threatens the safety of the entire circuit, but also causes some damage to the relay itself to a certain extent, which will definitely reduce its service life

At present, people have also designed some arc suppression circuits to avoid arc generation, such as capacitance, RC circuit and DRC circuit, but these circuits have the disadvantages of narrow application range, which may affect the system operation mode and anti-interference ability. Suitable as a method of arc suppression in control circuits

On the other hand, if the phase of the three-phase power is missing, the harm to the entire circuit system is also very serious, especially the destructive damage to the motor used.

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