Intelligent protector for three-phase asynchronous motor and control method thereof

Abstract

The invention discloses an intelligent protector for a three-phase asynchronous motor and a control method thereof. The protector comprises a single chip microcomputer, a three-phase current signal processing circuit, a three-phase current mutual inductor, a man-machine conversation circuit, a power circuit, a relay output circuit, an alarm circuit and a communication circuit. The single chip microcomputer is connected with the three-phase current signal processing circuit, the man-machine conversation circuit, the power circuit, the relay output circuit, the alarm circuit and the communication circuit separately, the three-phase current signal processing circuit is connected with the three-phase current mutual inductor, and the three-phase current mutual inductor is used for being connected with the three-phase asynchronous motor and detecting the current in the three-phase asynchronous motor. According to the intelligent protector, for the motors of different powers, the three-phasecurrent mutual inductor for detecting the current only needs to be replaced, and the intelligent protector for the motor does not need to be replaced; partial protection parameters do not need to be manually set, and the intelligent protector has the parameter self-learning capacity.

Description

technical field [0001] The invention relates to a power generation, distribution or transformation system in electricity, in particular to an intelligent protector for a three-phase asynchronous motor and a control method thereof. Background technique [0002] When the three-phase asynchronous motor is in normal operation, due to the current flowing through the three-phase three-phase windings, various losses are caused, and most of the losses are converted into heat, which makes the internal temperature of the motor rise. The temperature depends on the size of the winding current and its operation. If it is the normal temperature rise allowed by the motor, it will have no effect on the operation of the motor, but if there are some special conditions such as motor overload operation for a long time, stalling, power supply shortage, etc., the current of the motor winding will rise sharply, causing the temperature of the motor winding to also rise. The sharp rise will cause th...

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Problems solved by technology

[0002] When the three-phase asynchronous motor is in normal operation, due to the current flowing through the three-phase three-phase windings, various losses are caused, and most of the losses are converted into heat, which makes the internal temperature of the motor rise. The temperature depends on the size of the winding current and the operation. If it is the normal temperature rise allowed by the motor, it will have no effect on the operation of the motor, but if there are some special conditions such as motor overload operation for a long time, stalling, power supply shortage, etc., the current of the motor winding will rise sharply, causing the temperature of the motor winding to also increase. The sharp rise will cause the insulating varnish on the surface of the winding copper wire to melt and cause a short circuit, and in severe cases, the winding will burn out

[0007] The motor protector has many advantages such as energy saving, sensitive action, high precision, shock resistance and vibration, good repeatability, complete protection functions and long life, etc. Its disadvantage is that it is more complicated to use, especially the number of related protection parameters is large, and the protection parameters are uniform. It is artificially set, and the determination of the set value must have certain professional knowledge. If it is not set properly, it will not be able to play a protective role. In addition, the adaptability is poor. For different power motors and different working conditions, parameter adjustment or replacement of the motor is required. protector

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