The motor protection types mainly include the following:

Thermal relay: Suitable for ordinary small-capacity AC motors, where the working conditions are good and there is no frequent starting and other adverse working conditions. However, due to poor accuracy and unreliable reliability, it is not recommended.

Electronic type: detect three-phase current value, set current value with potentiometer or DIP switch, circuit generally adopts analog type, adopts inverse time limit or definite time limit working characteristics. Protection functions include overload, phase loss, stall, etc., fault type is displayed by indicator light, and running power is displayed by digital tube.

Intelligent type: detects three-phase current value, the protector uses a single-chip microcomputer to realize intelligent comprehensive protection of the motor, integrating protection, measurement, communication and display. The set current is set digitally and operated through the buttons on the operation panel. Users can modify and set various parameters on site according to the specific conditions of the motor; it uses a digital tube as a display window, or a large-screen LCD display, and can support multiple communication protocols, such as ModBUS, ProfiBUS, etc. The price is relatively high and is used in more important occasions; high-voltage motor protection uses intelligent protection devices.

Thermal protection type: A thermal element is embedded in the motor to provide protection based on the temperature of the motor windings, with good protection effects. However, when the motor capacity is large, it needs to be used in conjunction with the current monitoring type to prevent the motor windings from being damaged due to the lag of the temperature measuring element when the temperature rises sharply when the motor is stalled.

Magnetic field temperature detection type: Magnetic field detection coils and temperature measuring elements are buried in the motor to provide protection based on changes in the rotating magnetic field and temperature inside the motor. The main functions include overload, stall, phase loss, overheating protection and wear monitoring. The protection function is complete, but the disadvantage is that magnetic field detection coils and temperature sensors need to be installed inside the motor.

The above are the main types of motor protection. It should be noted that when choosing a motor protector, it should be determined based on the specific use environment and requirements.