Characteristics of motor phase loss
The specific manifestations of motor phase loss include increased vibration, abnormal noise, temperature increase, speed decrease, current increase, strong buzzing sound during startup, and inability to start.
The cause of motor phase loss is a problem with the power supply itself or connection, which may be due to improper fuse selection or poor compression, resulting in a broken fuse; Poor switch contact; Loose or broken connectors. It is also possible that one phase winding of the motor is disconnected.
After the motor is burned out due to phase loss, the intuitive fault feature of the winding is regular winding burn marks, and the degree of burn is not much different. Turn to turn, phase to phase, or ground to ground faults, where the location of the fault point is burned out particularly severely and the spread of faults is relatively lighter, are a characteristic that distinguishes phase loss faults from other faults.
Theoretical Analysis of Motor in Phase Loss Operation
● Electromagnetic and torque
When the motor operates in phase loss, there is a serious imbalance in the rotating magnetic field of the stator, resulting in negative sequence current generated by the stator. The negative sequence magnetic field and the rotor undergo electromagnetic induction, resulting in a potential close to 100Hz, causing a sharp increase in rotor current and severe heating of the rotor; During phase loss, the motor's load-bearing capacity decreases, leading to a sharp increase in stator current, with the most direct manifestation being motor heating. Due to the severe uneven magnetic field of the motor, the vibration of the motor is severe, leading to bearing damage. If the motor operates with load and phase loss, the motor will immediately stop rotating, and the direct consequence is the motor burning out. In order to prevent the occurrence of this problem, general motors are equipped with phase loss protection.
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Signal input
Signal type: Transistor (PNP&NPN compatible)
NPN signal level (input): NPN: 0-5VDC
PNP signal level (input): PNP: 15-30VDC
Single channel consumption current: 5mA
Port protection (input): overvoltage impact protection
Input characteristics: NPN/PNP (compatible)
Electrical isolation: AC 500V
signal output
Signal type: relay
Rated level: relay 250VAC/30VDC
Single channel rated current: Relay: 5A
Port protection (output): overvoltage and overcurrent protection
Electrical isolation: AC 500V
General parameters
Protection level: IP20
Working temperature: 0-55 ℃
Storage temperature: -25~85 ℃