A safety protection circuit for three-phase AC motor

Abstract

The invention discloses a safety protection circuit for a three-phase alternating current motor. The safety protection circuit comprises a rectifier filter circuit, an open phase and short circuit protection circuit, an undervoltage protection circuit, an overvoltage protection circuit and a motor control circuit. When any phase of the three-phase alternating current motor is open or locally short-circuited, the pin of a corresponding integrated circuit outputs a high level, a corresponding light-emitting diode is turned on, and a loudspeaker SW makes a sound to prompt people which phase is open or locally short-circuited. When an undervoltage or overvoltage fault occurs, the pin of the corresponding integrated circuit outputs a high level, the corresponding light-emitting diode is turnedon, the loudspeaker SW makes a sound, and meanwhile a delay protection circuit can disable the protection circuits in a certain period of time, thereby preventing the three-phase alternating current motor from frequent shutdown due to the rise or fall of short-time voltage. Thus, the three-phase alternating current motor can be safely protected from the faults of open phase, local short circuit, undervoltage and overvoltage, and meanwhile a sound and light alarm prompt can be given when the faults occur.

Description

technical field [0001] The invention relates to a protection circuit, in particular to a safety protection circuit for a three-phase AC motor. Background technique [0002] Three-phase AC motor is a kind of power equipment that converts electrical energy into mechanical energy to supply production machinery to realize various movements. It is widely used in machinery, metallurgy, coal, petroleum, chemical industry and other industrial fields. Generally, the research on the safe operation of three-phase AC motors is mainly aimed at the lack of phase operation of three-phase AC motors. The commonly used phase loss protection scheme is the protection scheme using two contactors, that is, the two contactors are respectively connected between the AB phase and the BC phase. It is not 0, but it is reduced, so the protection reliability of the above method is not high, and when the motor loses a phase, it is not clear which phase is missing, and the faulty phase cannot be found in...

AI Technical Summary

Problems solved by technology

The commonly used phase loss protection scheme is the protection scheme using two contactors, that is, the two contactors are respectively connected between the AB phase and the BC phase. It is not 0, but it is reduced, so the protection reliability of the above method is not high, and when the motor loses a phase, it is not clear which phase is missing, and the faulty phase cannot be found in time.

In addition, the existing method does not have overvoltage and undervoltage protection when the three-phase AC motor is running safely.

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