What Is Motor Protection?

Motor protection: Motor protection is to provide comprehensive protection for the motor, that is, overload, phase loss, locked rotor, short circuit, overvoltage, undervoltage, leakage, three-phase unbalance, overheating, bearing wear, fixed rotor eccentricity, axial movement diameter It will alarm or protect when it jumps; the device that provides protection for the motor is a motor protector, including thermal relays, electronic protectors and intelligent protectors. Large and important motors generally use intelligent protectors. Differential protection: The motor differential protection is equipped with differential quick-break protection and double-ratio differential protection with or without second harmonic braking. It can be used in the case of three-side differential current input (three-turn change). The complete and powerful acquisition function of the device voltage and current analog and switching values, equipped with standard RS485 and industrial CAN communication ports, and through reasonable configuration to achieve three-turn main transformer differential protection, two-turn main transformer differential protection, and two-turn distribution differential Protection, measurement and control functions such as dynamic protection, generator differential protection, motor differential protection and non-electricity protection. Overload protection: The coil of the miniature motor is usually made of very thin copper wire, which has poor current resistance. When the motor load is large or the motor is stuck, the current flowing through the coil will increase rapidly, and at the same time the motor temperature rises sharply, and the copper wire winding resistance is easily burned. If a polymer PTC thermistor can be connected in series in the motor coil, it will provide a timely protection function when the motor is overloaded to prevent the motor from being burned. The usual protection circuit is shown below. The thermistor is usually placed near the coil, so that the thermistor can more easily sense the temperature, making the protection more rapid and effective. The thermistor for primary protection usually selects KT250 thermistor with higher withstand voltage level, the thermistor for secondary protection usually selects KT60-B, KT30-B and KT16-B with lower withstand voltage level And chip motor.