What is the Difference Between VFD Electric Motor and Ordinary Motor Maintenance?

We all know that a VFD electric motor refers to a motor that runs continuously at 100% rated load in the range of 10% to 100% rated speed under standard environmental conditions, and the temperature rise will not exceed the rated allowable value of the motor. Is there any difference between the maintenance method of inverter motor and ordinary motor? Due to the particularity of the variable frequency power supply, the winding insulation of the electric vfd compatible motor is more stringent than that of the ordinary motor, so what is the difference between the VFD electric motor and the ordinary motor maintenance?

1. Winding and embedding construction technology of VFD electric motor

In the process of winding, embedding and binding, the inverter motor must be strictly managed, especially in the process of winding and embedding to prevent damage to the wire, and the insulation of the slot, phase insulation and interlayer insulation should be in place during the embedding process. The phase insulation should be made of materials that are easily penetrated by insulating paint, and the coil ends should be bound and fixed to ensure that the ends become a whole. Strengthen the insulation at the bottom of the motor slot, between phases, between layers and the first and last turns of the coil, which can improve the electrical strength of the motor.

2. The main insulation of the VFD electric motor must adopt no air gap insulation

The air gap in the insulation structure of the VFD electric motor is the main factor that produces corona. In order to ensure that there is no air gap in the overall insulation structure of the motor, according to the standard, the impregnating paint used for the special three-phase asynchronous motor for variable frequency speed regulation must be no less than F grade solvent-free paint, and the volatile content is less than 10%, and the VPI process is adopted. . The process of VFD electric motor power control equipment can also improve the overall mechanical strength of the insulation structure.

3. The VFD electric motor does a good job of matching the frequency converter, the cable and the motor

Do a good job of matching the inverter, cable and motor, and limit the length of the cable between the motor and the power supply. Due to the mismatch of power line impedance, as the length of the cable between the inverter and the motor increases, the amplitude of the overvoltage at the motor end increases, which is prone to cause partial discharge. To this end, the length of the connecting cable should be shortened as much as possible according to the specific variable frequency power supply characteristics and actual needs, so as to reduce the overvoltage amplitude and partial discharge at the motor end and prolong the life of the motor. Inverter motor power cables generally use professional cables, also known as symmetrical conductor variable frequency cables, which are 3P+3N/E series, that is, 1 in the original 3+1 is divided into 3.

Another point is that the electromagnetic wire of the VFD electric motor electrical transmission equipment has good corona resistance, which can meet the requirements of the motor to withstand high frequency pulses and partial discharges. Generally use polyesterimide / polyamideimide composite layer enameled wire, corona-resistant, anti-corona electromagnetic wire.