Plastic shell type electromechanical integration three phase ac electric motor protector

Abstract

The invention discloses a moulded case electromechanical integration three-phase AC motor protector, which is applicable to the protection of three-phase AC motors. Based on a moulded case circuit breaker or a moulded case leakage circuit breaker with a leakage protection function, the invention slightly changes the internal electric wiring, increases a special relay, a voltage loss release, three current detecting transformers and zero-sequence current transformers, and is provided with corresponding CPU and circuits outside the motor. The invention is suitable for the automatic breakdown of the three-phase AC motor in the situations of phase loss, electric leakage, overloading and rotor locking, reaching the function of motor protection and implementing the speciality and automation of the motor protection.

Description

technical field [0001] The invention relates to a three-phase motor protection device, in particular to a molded-case electromechanical integrated three-phase AC motor protector (switch). Background technique [0002] There are three types of damage to three-phase AC motors: [0003] 1. The motor is overheated, mechanically shaken or damp due to long-term use, resulting in reduced or damaged insulation performance. The three-phase power line fed to the motor rubs against the motor casing, causing leakage, endangering human life and causing electrical fires. [0004] 2. Overload and stall: When the motor is working, the motor cannot run normally and is stuck due to the change of load, which is called stall. Once a stall occurs, the motor will be damaged due to overload and stall within a few seconds. [0005] 3. The three-phase motor needs to be supplied with three-phase power when it is working. Due to the large number of contacts in the power s...

AI Technical Summary

Problems solved by technology

[0010] 1. It consists of two discrete components, thermal relay and AC contactor, which is inconvenient to install;

[0011] 2. In terms of protection performance, when using it, it must be accurately adjusted by a person with certain professional knowledge, and its sensitivity is extremely poor;

[0012] 3. There is no phase loss protection function and leakage protection function

[0016] 1. It must be completed by more than two components, namely the motor protector and AC contactor or automatic switch, which is difficult to debug and has low sensitivity;

[0017] 2. Most products lack leakage protection function

[0028] 1) When the voltage of the power supply system is low to a certain value, the leakage circuit breaker cannot work reliably and cannot protect the motor

[0029] 2) The three-phase circuit breaker with leakage protection function is equipped with a shunt release. When the trip is working, it is connected to the two phases of the three-phase power supply in parallel. The two-phase power supply connected to the release lacks any phase. , the release loses its working condition and cannot produce impact force. If the trip lever of the circuit breaker is knocked open, the circuit breaker cannot be broken, and the motor cannot be protected.

[0030] 3) General molded case circuit breakers do not have stepless continuous adjustable setting of working current and leakage protection function

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