Three-phase power supply phase failure detection method, device and an automatic transfer switch

Abstract

The invention discloses a phase failure detection method of a three-phase power supply, which belongs to the technical field of low-voltage electrics. The present invention aims at the problem that the existing phase-opening fault detection technology is affected by the connected load and easily leads to missing detection. The existing detection circuit is used to detect the A-phase phase voltage and the BC-phase voltage sampling circuit through the A-phase phase voltage sampling circuit and the BC line voltage sampling circuit. The phase difference (or phase angle difference) between the line voltages, according to the inherent change law of the phase difference in the case of phase failure, can realize the reliable detection of phase B or C phase failure. The invention also discloses a three-phase power supply phase failure detection device and an automatic transfer switch. Compared with the prior art, the invention is not affected by the connected load, has high detection accuracy for phase failure, and has simple circuit and low implementation cost.

Description

technical field [0001] The invention relates to a three-phase power supply phase failure detection method and device, and belongs to the technical field of low-voltage electrics. Background technique [0002] The automatic transfer switch has been widely used in the industrial power supply system, and the automatic transfer switch realizes the automatic transfer by detecting the fault state of the three-phase power supply which is normally used. The fault state of the three-phase power supply includes undervoltage, overvoltage, and phase failure. The detection of the phase failure of the three-phase power supply usually adopts the following two methods: one is to judge by detecting the phase voltage of A phase, B phase, and C phase Whether there is a phase failure, when the phase voltage of a certain phase is less than 30% of the rated phase voltage, it is judged as a phase failure; When it is less than 30% of the rated phase voltage or the BC line voltage is less than 30% ...

AI Technical Summary

Problems solved by technology

The first method can accurately judge the phase failure, but the hardware circuit is complicated and the cost is relatively high

The second method can save the hardware sampling circuit of one phase. The circuit is simple and the cost is low. However, since the output side of the automatic transfer switch is generally connected with loads such as voltmeters and power meters, the B-phase on the common or standby incoming line side of the automatic transfer switch Or when phase C is open, the detected line voltage value between phase B and phase C may be greater than 30% of the rated line voltage, which will cause the controller to make a mistake in judging that phase B or C is open, which will seriously affect the safety of the entire power supply system reliability

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