The role of interlocking device in variable frequency motor

Standard cage induction motors are generally fan-cooled, that is, wind blades are added to the output shaft of the motor. When the motor is running, the blades are rotated and cooled to discharge heat from the motor to achieve a thermal balance.

At present, the inverter motor on the market, if not specified when ordering, the default standard is to use independent fan cooling, the structure does not have blades on the motor shaft, instead a fan is installed in the fan blade of the motor. That is, the main motor cooling fan is driven by an independent motor.

Domestic professional inverter motor manufacturers do not produce fans, and fans of variable frequency motors are basically outsourced. Most of the matching fan motors use Class B insulation. With the experience of using variable frequency motors for many years, the highest failure rate of variable frequency motors is precisely the fan motor. Once the fan fails, the inverter motor will not be able to communicate internally due to poor ventilation. Emitted to cause a rapid rise in temperature.

In order to prevent the inverter motor from being burnt due to overheating of the fan, the heating of the motor and the operation of the cooling motor with load, in the process of converting electrical energy into mechanical energy, heat is generated due to loss. Generally, in the control protection, the variable frequency motor and its cooling fan motor are installed with interlocking, and the main motor is stopped once the fan motor is burnt or overheated.