Condensation in motors

[pugap]

For residential, outdoor condenser type motors (think of your central air conditioners), has anyone seen a good way of preventing condensation buildup inside the motor? Many motors fail due to rust buildup caused by condensation, but I've never seen a way of preventing this.

 

[jbartos]

Suggestion: The condensation inside of any space is often prevented by heating, e.g. by adding an electric heating element that evaporates the condensate inside. However, this will increase the electricity bill. Another approach is in suitable material resisting condensation and corrosion, e.g. stainless steel.

 

[teco]

pugap:- encapsulating the endwindings with dow corning 1890 paintable compound (when paintong windings also paint a coating on the inside frame) and fit sinted bronze pourous plugs to the lowest level of frame should help.
kind regds

 

[aolalde]

When the motor is running it generates by itself enough thermal energy to prevent condensation. Add space heaters that should be automatically turned on when the motor is not running. You will need an extra auxiliary NC contact to energize the heaters.

 

[rmw]

Put your anti-condensation heaters on a thermostat set for a preset temperature based on your ambient, and only run them when they are needed.

rmw

 

[busbar]

PSC-appliance motors — 48YZ {old ‘39 frame’} type are a huge commodity item, and on failure get replaced with fitsemall versions that may not effectively prevent ingress or allow drainage of rainwater. At best, “sealing” is usually a result of interference fit and no gaskets. Position of ventilating and weep openings probably has the most effect on survival, particularly for replacement motors.

To some degree, 1ø 460V PSC motors seem to e less tolerant to installation sloppiness compared to 200/230V versions.

 

[pugap]

Thanks all for feedback. Some clarification: condensation issue occurs typically after motor sits idle for some period of time (ie overnight, first startup in the spring). Remember these are in residential applications, so cost is a significant factor. There are already reasonable solutions to sealing & draining for rain water, but problem is the condensation buildup. Preheating is an interesting concept

 

[jbartos]

Suggestion: Another concept is to have a hemetically sealed enclosure that is filled with low humidity (dry) air.

 

[Farkel]

Another solution is to trickle charge the stator winding with 24VAC, by using a small isolation transformer, and putting it in the circuit of the starter by using the auxiliary contacts of the starter. Sizing of the transformer can be determined by the frame size of the motor in VA.

 

[jbartos]

Comment on the previous posting: This approach is physically realizable if the motor enclosure is open so that all water vapors can be released. If the motor is hermetically closed, the only way to remedy the conditions is by using the dry air.

 

[aolalde]

Jbartos. The original post states:

“Many motors fail due to rust buildup caused by condensation, but I've never seen a way of preventing this.”


Note; a hermetic motor do not have condensation problems since the ambient is not allowed to penetrate the motor internal parts (hermetic).

Reasonably if these motors have condensation problems, they are not hermetically sealed.

 

[jbartos]

Comment on the previous posting: Yes, hopefully not unless seals are leaky.