Electric motor failures due to conductive liquids
Electric motor failures due to conductive liquids
(OP)
We are experiencing an abnormally high failure rate with electric motors in our processing plant. We manufacture a salt that has a high pH (12+), a very high electrical conductivity, and very hygroscopic (it absorbs water from the air). It is also very corrosive to copper. Most of the failures result from windings shorting to ground. We have tried Mill and Chem duty as well as washdown duty motors. We specify motors with heavy, gasketed cast iron frames and covers. We also pack the conduit box with Dow Corning #4 non conductive grease.
Does anyone have any other ideas on how to reduce the number of failures?
Does anyone have any other ideas on how to reduce the number of failures?





RE: Electric motor failures due to conductive liquids
RE: Electric motor failures due to conductive liquids
Has transient overvoltage been ruled out, like that found in {480V} ungrounded distribution?
If 480V, it may be worth trying to operate lower-hp dual-voltage motors from a grounded 230Y/133V drive-isolation transformer.
Motor cycling may permit ingress during cooling periods.
RE: Electric motor failures due to conductive liquids
why not try epoxy impregnated windings as opposed to the VPI insulated windings?
It is a little more expensive and almost impossible to rewind them,but sounds like you have nothing to loose.
all the best
dadfap
RE: Electric motor failures due to conductive liquids
Sounds counter productive, but seems to work well for us in high humidty/temperature areas of our paper mill...
Richard Anderson
GP mill - Camas WA.
RE: Electric motor failures due to conductive liquids
RE: Electric motor failures due to conductive liquids
Our conduit is sealed with rubber gaskets under the fitting covers - we use RobRoy coated conduit in our Bleach Plant areas where Chlorine Dioxide can be a problem.
The condulet fitting drains I spoke of are designed to allow moisture to drip out yet discourage vapors from entering the conduit system. They are installed at the bottom of a conduit system usually using a TEE so that the motor lines are above the drains...
If your problem is extreme you might consider using explosion proof fittings and motors - though they are quite expensive...
Richard Anderson
GP Mill Camas, WA
RE: Electric motor failures due to conductive liquids
We plan to try the epoxy coated winding idea.
And yes, we suspect the heating and cooling of the motors is providing the driving force that pulls the salt into the motor.
We may look at installing the knockouts in the conduit -- it is worth a shot. However, one would assume that packing the motor conduit box with non-conductive grease would essentially eliminate the problem. It helps, but is not a cure-all.
thanks for all of your ideas. We are converting the worst offenders to air motors. All other ideas are welcome.
RE: Electric motor failures due to conductive liquids
RE: Electric motor failures due to conductive liquids
RE: Electric motor failures due to conductive liquids
Thank You,Radar. Duke Power
RE: Electric motor failures due to conductive liquids