(No) Impregnation for motor stators
(No) Impregnation for motor stators
(OP)
Have anyone tested the life of a motor without impregnation of the stator?
Do anyone know motors produced by someone without impregnation of the stator?
Do anyone know motors produced by someone without impregnation of the stator?





RE: (No) Impregnation for motor stators
RE: (No) Impregnation for motor stators
As the machine size increases, the electric attraction and repulsion between conductors increases with the current driven.
If the conductors are allowed to vibrate, eventually abrade the insulation leading to a failure.
The life of a winding without impregnation will depend on the machine size and how tight fits the winding into the slots, probably toy motors are made that way.
Large motors with medium voltages will last a few hours if not minutes.
RE: (No) Impregnation for motor stators
What size motors.
What do you mean by no impregnation? No global vacuum impregnation? What about a B-stage coil... do you consider that impregnated? Large motors can be made with B-stage coils (no VPI) and operate reliably for decades.
VPI is the state of the art and preferred for high end applications imho.
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RE: (No) Impregnation for motor stators
RE: (No) Impregnation for motor stators
Form wound mv windings (3.3 KV and above) may be vacuum pressure impregnated with B stage coils or use resin rich non-impregnated coils, both systems having been time tested.
Advantage with resin-rich system (non-impregnated) windings is that it is easier and cheaper to rewind them.
pete,
I have not come across machines being operated with B stage coils, which are only semi-cured and are not fully fit for dielectric stresses until they are fully cured under VPI (global or coil wise)
RE: (No) Impregnation for motor stators
The curing occurs under high temperature when the stator is baked after winding.
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RE: (No) Impregnation for motor stators
http://www.electromash.com/eng/elremob/p6/elremob_p6.htm
http://www.nwibrt.org/Specifications/acmotor.doc
etc. for more info
RE: (No) Impregnation for motor stators
RE: (No) Impregnation for motor stators
This insulation is broadly used on form-wound Generator stators 7.5 to 15 kV. The coils are cured in a molded-press under temperature.
Isola and US-Samica are some of the leading tape manufacturers in USA
RE: (No) Impregnation for motor stators
http://www.electromash.com/eng/elremob/p6/020105.htm
for the testing equipment.
If installed unimpregnated, then the slots have to be insulated.
http://www.cedrat.com/software/motor-cad/pdf/Motor-CAD_IEMDC_2001.pdf
for:
Additional methods used to increase the winding
dissipation include improved winding impregnation
techniques and potting of the end-windings. Vacuum
impregnation can eliminate air pockets within the winding.
For instance the winding shown in Figs 5 & 6 benefit from a
decrease in temperature rise of around 9% when the motors
are perfectly impregnated compared to a 50% impregnated
motor.