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The danger of moisture to electric motors

Along with heat, dust and inadequate lubrication, moisture is one of the most common causes of electric motor failure. Here's why moisture is such a threat to efficient, reliable motor operation and how to avoid it.

When a warm motor shuts down, it draws cool air in, which will always contain moisture. Condensation then forms which can be absorbed by the porous winding insulation. If the moisture does not get the opportunity to dry out, it will cause the insulation to deteriorate and lead to corrosion of the windings.

Motors operating continuously generate enough heat to ensure windings and other components are kept dry, but those that are out of service for extended periods are susceptible to moisture accumulation.

Users can alleviate the problem by opening the drain holes at the motor’s lowest point to allow any moisture to escape. Alternatively, moisture-proof covers made from plastic or waterproof fabric can be obtained and bound tightly round the motor body.

A more reliable solution is to install space heaters either within the motor or on the external casing, which will keep winding temperature warmer than the air outside.

For all electric motor enquiries, whether you’re looking to place an order or arrange a motor rewind, call Gibbons on 01621 868138 or email

Electric Motors

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