Common motor thermal protector is divided into the following types
Motor thermal protector: detection of three-phase current value, setting current value using potentiometer knob or code switch operation, the circuit generally adopts analog, using inverse time limit or fixed time limit working characteristics. Protection functions include overload, phase loss, blocking, and other fault protection, fault type is displayed by an indicator light, running power is displayed by digital tube.
Thermal protection motor thermal protector: embedded heat elements in the motor, according to the temperature of the motor protection, protection effect is good, but when the motor capacity is large, it needs to be used with the current monitoring type, to avoid the rapid rise in the temperature of the motor blocking rotation, because of the hysteresis of the temperature measuring element, resulting in damage to the motor windings.
Intelligent motor thermal protector: detects the three-phase current value, the protector uses a single-chip microcomputer to realize the intelligent comprehensive protection of the motor, which integrates protection, measurement, communication, and display.
Magnetic field temperature detecting motor thermal protector: embedded in the motor magnetic field detecting coil and temperature probe, according to the change of the rotating magnetic field inside the motor and the change of the temperature, the main features include overload, blocked, lack of phase, overheating protection and wear monitoring, perfect protection function, the defect is installed inside the motor magnetic field detecting coil and temperature sensor.