Phase number of motor
There are many kinds of motor classification methods, which could be divided into single-phase motor and three-phase motor according to the number of power supply phases.
1) Single-phase motor power supply is a common power supply for general households, which consists of one phase.
The power supply itself cannot run the motor. In order to start the motor, it is necessary to connect the capacitor and the auxiliary coil to start.
2) Three-phase motor is divided according to power, and consists of three power supplies whose phase voltages are 120 degrees out of phase.
The motor is connected to the power supply and driven, that is, a rotary magnetic field is generated, and the motor can be started. The efficiency of the motor is very high, and the starting torque is also very large.
Volcano - motor, basically, all product motors are three-phase motors.
The open-phase protector is a kind of circuit protector, which is also called motor open-phase protector or power supply open-phase protector. This kind of open-phase protector is mainly used in three-phase motor circuit. The open-phase protector is mainly to protect the motor or the equipment related to the motor.
Working principle of open-phase protector
Lack of phase means three-phase power supply, but two phases or only one phase instead of three phases.
The motor can't work normally after the power supply of three-phase motor is out of phase, and the winding of motor coil will burn out if one-phase power is out of phase for a long time. If the three-phase 380V power supply is used to change the control power supply to 220V, there will be no 220V voltage due to the out-of-phase power supply.
Use a multimeter to measure the phase-to-phase voltages of the three-phase power supply. If they are not all around 380V, the power supply is out of phase. At low voltage, continuous operation will lead to a great increase in operating current, which may burn out the motor. Three-phase wires are wound around an iron core at the same time. When the three phases are balanced, the magnetic flux of the iron core is 0; When the three phases are unbalanced, the magnetic flux of the iron core is not zero; The detection coil wound around the iron core also generates induced electromotive force, which is amplified to control the tripping protection of contactor.