About motor protection
Thread Content
Traditional motor protection devices are mainly fuses and thermal relays. Can they protect the motor from phase loss and burning?
The components are reliable and the parameters can be adjusted appropriately.
The fuse only protects the circuit from short circuits. Thermal relays can be used as overload and phase loss protection, but their phase loss protection performance is not reliable. At present, automatic air switches are commonly used to replace fuse protection, which can effectively avoid the phase loss of the motor caused by the fuse blowing in one phase. The use of intelligent motor protectors can provide comprehensive protection for the motor, including undervoltage, overvoltage, overcurrent, stalled rotor, three-phase current imbalance, phase loss operation and other faults.
Contemporary motor protection technology has produced fundamental changes. This change comes from the change in its protection principle. For example, the short circuit and phase loss protection of the motor is realized by judging the zero sequence and negative sequence current of the motor. The basis is the symmetry principle of the three-phase AC system. Although the voltage and current of the motor are also detected, the effectiveness of the protection will be more direct and reliable.
The fuse heating relay cannot provide phase loss protection, but each circuit has a circuit breaker, which should be able to provide phase loss protection.
As mentioned on the third floor, adding a protector is not expensive and the protection is much more reliable.
The motor protector is a bit larger. If there are more motors to be protected, the cabinet will be tighter, but the protection effect is much better than that of a thermal relay. Because of the high resolution, I also used this to protect the heater. Prevent the heater from disconnecting.