When it comes to supplying a reliable service to a customer how much faith should I put in the results from typical motor testing programs? We have multilins to shut off the motor before too much damage occurs and we do surge tests, circuit analysis and megger tests at least once a year. What are the chances that a motor will fail without any warning? Is it good practice to have spares no matter how diligent the maintenance department is at testing the motors?
Answer:
Annual testing is not frequent enough for PdM. Your multilin will shut off equipment after a fault occurs, providing only a little more protection than an overload. Equipment of this type is meant to be circuit and load protection, not motor protection. Predictive maintenance, on the other hand, is meant to be a series of repeatable measurements that can trend a fault over time. The more frequent the readings, the more accurate the program. Annual testing provides no more than a spot-check. Therefore, if you are only testing annually, then, yes, you must have a large number of reactive spares. Once test results are trended more frequently, and corrections are made to correct the root-cause of faults, then you can decrease your spare inventory.
Sincerely,
Howard W Penrose, Ph.D. General Manager
ALL-TEST Pro BJM Corp
123 Spencer Plains Rd
Old Saybrook, CT 06475
Ph: 860 399-5937
Fax: 860 399-7784
www.alltestpro.com