Improper burnout and cleaning of a stator can ruin an otherwise repairable motor. The
frame and laminations can warp or break if the job is not done properly. Proper burnout
and cleaning will add to the operating life of the motor and help reduce the electrician's
During this lesson, we will discuss the heating of stator windings prior to coil
removal by both the burnout oven and radiant heating methods. We will then discuss
coil removal by both the hand and power removal methods.
It is necessary to soften the hardened varnish and loosen the insulating materials
enough to allow for their removal. Regardless of the methods used, you must remember that,
because of heating, there is always a chance of personnel injury. In addition, you may be
using a power cutoff saw to remove winding end turns and hydraulic pullers for coil
removal. Again, the need to be especially careful cannot be overemphasized.
You will also complete and verify the rewind information that you compiled during the
lesson on winding identification and data taking.
Burnout and heating of windings
burnout oven method will be used for standard and T-frame motors only.
Preheat oven to a maximum of 700°F for standard motors and 600°F for T-frame motors.
The maximum surface temperature of the laminated iron surface should be measured on the
iron by thermocouple and must not exceed maximum temperature.
a core loss test before and after burnout.
Remove the crown of the winding opposite the connection end.
Place the stator in the oven for approximately 12 hours or until all
insulating materials have turned to ash.
use insulated gloves and eye protection when removing the stator from the oven.