motor
- Thread starter jimbo123
- Start date
- Status
- Location
- Illinois
- Occupation
- retired electrician
Trickling power puts a low level current through the windings and the current causes heat in the windings and that heat will prevent the condensation.
As far as drains the can be used to drain out the condensation, but will not prevent it and may even increase it.
As far as drains the can be used to drain out the condensation, but will not prevent it and may even increase it.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Yes, the drain plugs only take care of moisture that collects on the lowest places, but the bigger problem is moisture that gets absorbed by the winding insulation material, and only the heating method can prevent that or get rid of it if it happens.
The tricky part of using a low level current through the windings is in preventing that from damaging the windings or damaging the trickle current system. There are electronically controlled anti-condensation heaters available from Allen Bradley and Motortronics, plus a number of VFDs and a few soft starters offer that capability as built-in features. Building your own can be done, but getting the voltage correct so that the current is not too high or the resistance in the windings too low is tricky and usually involves some experimentation (or experience). You also have to have a timer that makes sure you don't apply any voltage to the motor if it is still energized or is still coasting.
The tricky part of using a low level current through the windings is in preventing that from damaging the windings or damaging the trickle current system. There are electronically controlled anti-condensation heaters available from Allen Bradley and Motortronics, plus a number of VFDs and a few soft starters offer that capability as built-in features. Building your own can be done, but getting the voltage correct so that the current is not too high or the resistance in the windings too low is tricky and usually involves some experimentation (or experience). You also have to have a timer that makes sure you don't apply any voltage to the motor if it is still energized or is still coasting.
When motors [50hp] are under water due to flooding , is it best and more time efficent to remove motors and send them to a motor shop to dry them out ?
Or will a trickling voltage factory unit made by motortronics that is used to keep the inside of motors warm when not in use be enough to dry out the windings of the motor ?
Or will a trickling voltage factory unit made by motortronics that is used to keep the inside of motors warm when not in use be enough to dry out the windings of the motor ?
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
I suspect a motor winding that is flooded should be looked at by someone who knows what they are doing rather than trying some gizmo to dry them out.
I am in the camp of motors that get used regularly are not a candidate for needing motor winding heating to deal with potential condensation. I have always reserved them for motors where they sit for long periods of time without being used. I also think it is not worth putting them on smaller motors.
Many of the motors we deal with have separately powered anti-condensation heaters. They are interlocked such that they are switched out when the motor is powered up.
I'm with you on the trickle system.
I think it is fraught with risks and best avoided.
Trickling power heats the insulation by using the coils of the motor. Motor inulsulation is better than ever but it is still hygroscopic- that is it absorbs water. A running motor is warm and heat generated in the windings keeps the water out of the insulation.
When a running motor stops and cools down moist air can be drawn into the case and the air in the case cools down and the water condenses and can be drawn into the insulation. Heating schemes keep the temperature of any air in the case above the dew point.
I don't think much of trickling power through the coils. It can be expensive to install and may void the listing of your starter.
My first step would be:
1.) Get all the information on a trickling system and determine where the components are going to go, what conduit and wiring you'll need and estimate you cost and down time.
2.) Check the price of just buying new motors with strip heaters. Us an "a" contack in the starter to operate the heater.
#2 has worked for me in that the downtime was less. YMMV
Either way you should have a source of power seperate from the motor power system. For example using power from an MCC mounted transformer and panel defeats the purpose of a motor heater. When the MCC goes down every motor fed from it (with a heater source fed from that MCC) is going to start sucking water.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
- Status