Method for implementing middle phase zero division zero sum by control protection switch

Abstract

The invention relates to the technical field of motor control, in particular to a method for realizing medium phase zero-breaking and zero-closing by a control protection switch. The control protection switch is a carrier to realize the method, and comprises a central processing module and a contactor module. The method is characterized by comprising the following steps that: a main CPU singlechip of the central processing module acquires a voltage signal through a voltage signal acquisition circuit, and acquires a current signal through a current signal acquisition circuit; then a three-phase electricity zero-crossing point period is compared with electrified closing mechanical time and power off breaking mechanical time of the contactor module; and a closing or breaking signal after judgment is sent so as to close or break the contactor module of the control protection switch on the medium phase zero point of the three-phase electricity. The method is a simple and effective method for relieving the overvoltage and overcurrent impact, improves service life of the switch body, reduces abrasion of a contactor material, and reduces consumption of noble metal resources.

Description

Technical field [0001] The present invention relates to the technical field of motor control, in particular to a method for controlling a protection switch to realize a neutral phase zero opening and closing. Background technique [0002] At present, the existing motor control and protection systems generally consist of circuit breakers, contactors, thermal relays and even time relays. The circuit breakers have only over-current protection functions, and the service life is about 10,000 times; the contactors have a long service life , But does not have the breaking capacity; the thermal relay has single protection function, low accuracy, and unstable action. The investigation found that more than 90% of asynchronous motors are damaged by overheating of the stator winding, and nearly 60% of them are caused by phase failure. The thermal relay is unreliable as a phase failure protection. [0003] In addition, a new type of electrical equipment has appeared in recent years: control a...

AI Technical Summary

Problems solved by technology

[0005] However, the existing control and protection switching equipment is instantaneously broken when it is pulled in and broken. In this way, the overvoltage and overcurrent generated at the moment of circuit start and stop will not only impact the circuit work, but also cause fluctuations to the power grid, which will seriously affect the electrical system. equipment life, and produce strong electromagnetic interference to the surrounding working circuits, which is a serious technical defect that the current control and protection switchgear has not yet overcome

Images