Industrial Vacuum Impregnation Process for Motor Windings With Drying Function

1. Application

The vacuum impregnation and drying machine employes a compound

process of “hot air-vacuum environment-hot air”, which enables the

windings to be impregnated and dried in a sealed container. The vacuum

impregnation equipment has advantages of advanced design, scientific process,

compact structure, easy operation, safety and reliability, good sealing, and

reduced laboring strength. The vacuum impregnation process for motor

windings is used for vacuum impregnation treatment of windings of

general motors, electrical equipment, special motors, pump motors,

magnetic motors, transformers, and iron cores. This vacuum varnish

impregnation machine is a newly energy-saving equipment, which greatly

improves product quality, reduces production cost, and strengthens competitiveness.

2. Technical Parameters

Note: AT refers to ambient temperature.

3. What is vacuum impregnation and drying process?

A process has different insulation structures and different technical requirements,

and its actual process parameters are also different. For example, VPI has four process

parameters, namely vacuum VI, pressure PI, temperature Ti and time ti, where I is

1, 2, 3,..., n (n is the total number of VP process and I is the process sequence).

Insulation structure (W), technical index (a) and resin liquid characteristics (E) are the

basic functional elements of these four process parameters. The resin dipping insulation

treatment process of motor and transformer windings has been through the following stages:

immersion impregnation (ordinary impregnation), then multiple impregnation, then dripping,

rolling and impregnation, and finally integrated impregnation and drying treatment process.

It has formed a series of mechanized continuous operation and automatic control impregnation

process with modern computer technology and PLC technology. This is a gradual evolution

and development through the promotion of technological innovation, production demand

and social development. It is this promotion that has produced a new generation of vacuum

impregnation dryer, high-tech products and famous brand products integrating

energy conservation and environmental protection.

The new generation of vacuum impregnation drying machine is a mechanical insulation

process in which the workpiece is put into the impregnating tank for pre drying, the air

and volatiles inside the coil are removed in the vacuum environment, and then the

resin is immersed under the vacuum condition by relying on the gravity of the resin

liquid and the capillary action in the coil, so that the resin liquid can quickly

penetrate and fill the inner layer of the insulation structure.

FGH process flow → putting in parts → pre drying of windings→

vacuum dehumidification → vacuum impregnation →resin dripping→ cleaning →

return cleaning agent → drying at low temperature and curing at high temperature →

thermal insulation → unloading. The vacuum impregnation drying machine carries

a fully sealed and environmental pollution free treatment process which is

completed at one time.

Advantages of FGH: in the scope of application of FGH process, its advantages

are mainly in the following aspects:

(1) Improve the integrity. Due to the vacuum impregnation, the insulating resin

almost completely fills the interior of the insulation, which strengthens the

integrity of the whole winding. Each part of the winding will not move separately

during operation, reducing the faults caused by moving wear.

(2) Improve the environmental resistance. The vacuum imprenation and drying

process is carried out and completed under the condition of fully sealed container.

The whole drying process adopts hot air circulation heating, and the waste gas

is recovered and discharged through group A and B condensers, so as to improve

the working environment and meet the requirements of environmental protection.

(3) Reduce the operating temperature and temperature rise. Due to the complete

filling of impregnating resin, the insulating resin can well replace the internal air

gap and improve the thermal conductivity. It can generally reduce 5-10 ℃ for

motors and transformers.

(4) Improve the performance of the workpiece. Due to the integrated vacuum

impregnation and drying process, the whole winding is tightly encapsulated

and soaked by the impregnation resin, and the surface resin film is smooth

and bright, so that pollutants, wet gas and chemical gas cannot enter the inner

layer, and the fault caused by the bridging of conductive medium is eliminated.

(5) Save energy and reduce costs. Due to the integration of vacuum resin

impregnation and drying, the drying time is two fifths shorter than that of the

oven, and the drying temperature is 10-20 ℃ lower than that of the oven,

so as to further increase production, save energy and reduce costs.