Default-phase-preventing, overvoltage-preventing and interference-preventing automatic protector of motor and protection method thereof

Abstract

The invention relates to a default-phase-preventing, overvoltage-preventing and interference-preventing automatic protector of a motor and a protection method thereof and belongs to the technical field of protection devices of three phase alternating current motors. The automatic protector comprises a power circuit, a PLC control circuit and a default-phase detection control circuit, wherein the power circuit is used for providing +15V voltage, -15V voltage and +5V voltage for the default-phase detection control circuit. The PLC control circuit is used for enabling the motor to stop rotating when the motor rotates normally and the voltage is overlarge. The default-phase detection control circuit is connected with the PLC control circuit and used for detecting whether frequent default phase is caused by motor circuit 'visual connection' or other reasons or not and then performing an action instantly. The protector is a time-delay protector. When the default phase time is smaller than the delay time due to occasional default phase caused by a power supply department, a default phase protection action is not performed. When the default phase time is larger than the delay time due to the frequent default phase caused by the motor circuit 'visual connection' or other reasons, the default phase protection action is performed.

Description

technical field [0001] The invention relates to an automatic motor protector against phase loss, overvoltage and interference and a protection method thereof, belonging to the technical field of protection devices for three-phase AC motors. Background technique [0002] In three-phase low-voltage power distribution lines, phase loss or overvoltage often occurs, which will have a great impact on the normal operation of the circuit load, especially the motor. Therefore, in actual operation, the phase loss or overvoltage of the main circuit It can play a protective role, but because the protection circuit in reality is basically instantaneous, it will be protected immediately when there is a phase loss, and this time the phase loss is caused by the power supply department, and the power supply will be restored immediately, so this protection is unnecessary , if the machine tool is processing the workpiece, it will inevitably affect the quality of the workpiece. At the same time...

AI Technical Summary

Problems solved by technology

[0003] To sum up, the problems existing in the existing motor protectors are: (1) In the three-phase low-voltage power distribution lines, if the protection circuit used is of instantaneous type, the protector will often protect the motor when no protection is required. , which will affect the production efficiency; (2) In the three-phase low-voltage distribution line, if the protection circuit is not used, the motor will have phase loss or overvoltage during operation, which will cause equipment damage

Images