Motor protection refers to technical measures implemented to trigger alarms or provide protection when a motor experiences faults such as overload, phase loss, locked rotor, short circuit, overvoltage, undervoltage, leakage, three-phase imbalance, overheating, bearing wear, rotor-stator eccentricity, etc. These measures are achieved through thermal relays, electronic protectors, and intelligent protection devices. The protection devices monitor parameters such as current, voltage, and temperature, and use techniques like three-phase true effective value calculation and winding heating model simulation to determine the fault state, thereby triggering power disconnection or triggering alarms. The protection range covers overcurrent, short circuit, and other operating conditions. Important motors often integrate current display, temperature monitoring, and local reset functions [1-3].
Traditional thermal relays have gradually been replaced by electronic protectors due to their low sensitivity. The latter achieve overload protection through inverse-time characteristics. Intelligent protectors integrate parameter display functions and support industrial communication protocol conversion [1] [3]. The “Made in China 2025” initiative proposes that by 2025, 100% of power transmission and transformation complete equipment will be fully intelligentized, promoting the application of intelligent protection devices in automated production lines. The selection should take into account motor parameters, load characteristics, and environmental conditions. For ordinary working conditions, electronic protectors can be selected, while in smart grid scenarios, devices with sensor integration features should be configured [1] [4].