Four major differences between variable frequency motors and ordinary motor repairs

As we all know, the variable frequency motor is a motor that operates continuously under the standard environmental conditions with a rated load of 100% to 100% within the rated speed range, and the temperature rise does not exceed the allowable value of the motor. What is the difference between the maintenance method of the inverter motor and the ordinary motor? Due to the special nature of the variable frequency power supply, the winding insulation of the variable frequency motor is stricter than that of the ordinary motor. For details, let Xiaobian bring everyone to have a look!

First, select a magnet wire with good corona resistance to meet the requirements of high frequency pulse and partial discharge. Polyimide imide/polyamide imide composite layer enameled wire is generally used, which is resistant to corona and corona resistance.

Second, the winding, inlay construction process.

The processing technology of the variable frequency motor in winding, weaving, tying and so on must be strictly managed, especially in the process of winding and weaving, to prevent damage to the wire. The weaving process should ensure that the slot insulation, phase insulation and interlayer insulation are placed in place. Phase insulation should be made of materials that are easily impregnated with insulating varnish. The ends of the coil should be reinforced and secured to ensure that the ends are integrated.

Insulation is reinforced at the bottom of the motor slot, between the phases, between the layers, and at the end of the coil to improve the electrical strength of the motor.

3. The main insulation shall be insulated with no air gap.

The air gap in the insulation structure of the variable frequency motor is the main factor for generating corona. In order to ensure that the overall insulation structure of the motor does not contain air gap, according to the national standard GB/TZ1707-2008 "Insulation specification for three-phase asynchronous motor for variable frequency speed regulation", the impregnating paint for the three-phase asynchronous motor for variable frequency speed regulation must be It is lower than the F-grade solvent-free paint and has a volatile content of less than 10%, and adopts the VPI process. The process also improves the overall mechanical strength of the insulation structure.

4. Do a good job of matching between the inverter, cable and motor, and limit the length of the cable between the motor and the power supply.

Due to the mismatch of the impedance of the power line, as the cable length between the inverter and the motor increases, the amplitude of the overvoltage at the motor end increases, which is prone to partial discharge. To this end, according to the specific characteristics of the variable frequency power supply and actual needs, the length of the connecting cable should be shortened as much as possible to reduce the overvoltage amplitude and partial discharge of the motor end and prolong the life of the motor.

The variable frequency motor power cable generally uses a professional cable, also called a symmetric conductor frequency conversion cable, which is a 3P+3N/E series, that is, the original 3+1 is divided into three.