Electrical Troubleshooting Quiz — Jan. 7, 2020
One of the major lines in the plant rarely had problems. Then about three months ago, it started experiencing problems every other week or so. The most common problem is repeated failure of a particular drive motor. It's been replaced multiple times.
The plant's electrical testing firm conducted a power quality analysis on the branch circuit supply and reported no anomalies. They ruled out low power factor, excess harmonics, waveform distortion, and other power quality issues. They even left a portable power monitor on the branch circuit for three days, during which time a failure occurred. The power monitor didn't record any events that could be causal to that failure.
How might you identify the cause?
These problems are symptomatic of not one, but multiple, botched repairs. For example, why has that motor been replaced multiple times?
Go back to one month before the downtime crisis started. From that point forward, document which failures occurred, and which replacement parts were used. Next, go to the latest drawings for that equipment and determine which replacement parts should have been used.
For example, the drive motor that keeps failing might be a Design D because that's what was in the stock room but the drawings call for a Design B. Or maybe there is a different temperature rating. Look at thermal overloads; a mix-up here could easily account for so many failures of the same part number of motor.
Motor failures are often attributable to incorrect lubrication. Who is replacing these motors and are they lubricating the motors? If so, look for a grease incompatibility problem.
About the Author
Mark Lamendola
Mark is an expert in maintenance management, having racked up an impressive track record during his time working in the field. He also has extensive knowledge of, and practical expertise with, the National Electrical Code (NEC). Through his consulting business, he provides articles and training materials on electrical topics, specializing in making difficult subjects easy to understand and focusing on the practical aspects of electrical work.
Prior to starting his own business, Mark served as the Technical Editor on EC&M for six years, worked three years in nuclear maintenance, six years as a contract project engineer/project manager, three years as a systems engineer, and three years in plant maintenance management.
Mark earned an AAS degree from Rock Valley College, a BSEET from Columbia Pacific University, and an MBA from Lake Erie College. He’s also completed several related certifications over the years and even was formerly licensed as a Master Electrician. He is a Senior Member of the IEEE and past Chairman of the Kansas City Chapters of both the IEEE and the IEEE Computer Society. Mark also served as the program director for, a board member of, and webmaster of, the Midwest Chapter of the 7x24 Exchange. He has also held memberships with the following organizations: NETA, NFPA, International Association of Webmasters, and Institute of Certified Professional Managers.