Drying Out an Alternator

"Plz suggest me a good soln."

I suggest the use of whole words and spell check. That helps here every time being they are both free here.

I don't see how drying the alternator out is going to help you if the winding has in deed gone open circuit during an insulation resistance test failure.

If the winding is still fine and you just want to dry the motor out, and you don't have a big enough oven, you could just disassemble the alternator as much as practical and then build a small enclosure (vented or sealed depending on what drying method you want to employ) around the alternator and use as many home or commercial fan heaters as necessary to blow hor air across, through and around the disassembled alternator (the heaters are not expensive). Keep it simple!

Be careful if you use wood for your makeshift oven.

since its monsoon season it is going to show insulation failure.

well thanks for ur kind suggestion.

To heat the windings DC will not cause rotation and voltage stress on insulation is minimal.

Some air blown through the alternator will carry away the water vapour.

Rectified AC will cause minimal winding ripple and modest extra insulation stress.

"Plz tell me any simpler process to dry it OUT"

You can apply low voltage AC or DC to winding to heat up winding of Generator; this is not simple as keeping heat blowers and heating.

I share my experience here! During 1982 I was working at Bargi Masonry Dam construction project as Electrical section in-charge; due to sudden flash floods in the river Narmada all our electrical panels, motor starters, Tower crane panel, motors, cables, etc went under river mud water for one month. I have dried every thing after cleaning the mud with water jet; more than 600 motors, panels, even cables, etc using "Heat convector's" (heat air blowers) that many people use in Northern India.

yes you are right

A usual approach would be to try to get heat into the winding without applying a lot/any load. If it were possible to bottle up the generator (block the cooling passages) and run the unit at speed no load the heat of windage may be enough to dry things out.

The other option is to hook up a welding machine and warm it up with current. I don't remember the exact details of how we did this so I would suggest getting someone with prior knowledge before attempting this method. You will need a welding machine and a shunt at the minimum.

Of course this is formulated with entirely too little information, such as what happened to cause the problem, what electrical tests are prompting you to believe that the winding is wet, what is the history of the problem ,etc.

I'm not sure how big your alternator is but if it has a manual excitation mode and metering then you can try this. Bolt all three phase leads together with a suitably sized piece of buss bar with properly torqued bolts (suitably sized means capable of carrying rated current without overheating). Spin your alternator up to rated speed with absolutely no excitation applied, then slowly (starting at zero field) apply the field until the alternator output is about 90% of full rated current (the terminal voltage will be near zero, after all it's feeding a short circuit!) Monitor carefully for about 8-16 hours after the temperature stabilizes near its rating. You're looking for the temperature to rise due to the fact that full load current is circulating through the windings. You should monitor the outlet temperature and perhaps the dew point of the cooling air if you have that capability, but the most important thing to watch is that the phase currents are within a few percent of each other and that the temperature of your bolted three phase short circuit connection is not too high. Periodically you should shut the system down and check the PI (polarization Index) and/or the insulation resistance with the appropriate instruments. When it's where you want it to be you're done.