A Unique Solution to Improving Motor Winding Life in Medium-Voltage Motors

It has been recognized for years that electrical motors installed in petrochemical plants require protection from condensation. Papers have compared different methods of preventing condensation from collecting in 600-V motor windings. These papers covered the advantages of directly heating the motor windings by introducing a low-voltage ac or dc source to the windings when the motor is not running. Their conclusion was that low-voltage heating. is the most practical solution to motor moisture problems since the heat is evenly distributed throughout the stator windings and does not cause hot spots in the windings as conventional motor heaters can. Many installations in recent years have proven the reliability of this low-voltage application to windings. A case history is given of retrofitting a newly developed motor windings heater to an existing 5000- hp 2300-V synchronous motor that has had numerous winding failures due to moisture. The installation is at ARCO Chemical Company's Port Arthur, TX, plant.