Plant Services - August 2007 - (Page 47) RELIABILITY Motors Internal connections L Start winding Rotor Centrifugal switch Start capacitor N Main winding Figure 4. Schematic of a capacitor-start, induction-run motor. performance tests, including temperature rise, locked rotor and breakdown tests as well as motor build and inspection analyses (MBIA). In the MBIA, the sample motors are torn down to investigate and compare component quality to the incumbent. Plants should consider installing severe-duty motors, such as IEEE Standard 841 motors, if the motor might be exposed to harsh conditions. The 841 motors have been designed to survive in the chemical and pulp and paper industries. Determine and document the cause of motor failure. Include maintenance history and whether the motor was new or repaired. Use tools such as the Motor Master to decide whether to repair or replace. It’s important that you make this decision only after a thorough failure investigation. The data will come in handy someday and form the basis of future reliability decisionmaking. For example, assuming a plant establishes that a new motor lasts twice as long as Headline motor and there are large costs associated with a rewound process downtime, then there should be some benefits derived from a motor that fails less frequently. This benefit can easily be calculated using an Excel spreadsheet. If you decide to repair, write a good repair specification and ensure that the repair facility is qualified. The U.S. Department of Energy (DOE) has developed guidelines for motor repairs that can be accessed on the Web. Also, a list of qualified service centers as well as guidelines on good repair practices can be obtained from the Electric Apparatus Service Association (EASA). Furthermore, there are certification programs available to qualify motor service centers. Usually, motor service centers that are accredited by the Advanced Energy’s Proven Excellence Verification (PEV) certification program have demonstrated full competence supported by rigorous audits and testing. Emmanuel B. Agamloh is Senior Motor Systems Engineer at Advanced Energy in Raleigh, N.C. Contact him at eagamloh@advan cedenergy.org and (919) 857-9023. Watch it all come together at Alemite.com/products. 07ALE326 www.Alemite.com August 2007 www.PLANTSERVICES.com 1808_07ALE326Ad_PS.indd 1 3/16/07 3:10:03 PM 47 http://Alemite.com/products http://www.Alemite.com http://www.PlantServices.com
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