Electrical Troubleshooting Quiz — April 21, 2020
The plant has seven production buildings, A through G. In building C, the motor failure rate is nearly five times that experienced in the other buildings. You're being told this while interviewing for a newly created position as plant electrical engineer, after you asked the existing plant engineer, “What keeps you up at night?”
Now the bases are loaded, and you’re up at bat one more time. Can you hit a home run? Here's the pitch: All the motors are maintained the same way, so the error is not due to motor lubrication or other maintenance failures. Nobody knows where to look for the cause. What do you suggest?
Begin by asking what is different about Building C. Does it have a large non-linear load, such as a big motor, that starts across the line? Are there any other load differences? What is the nominal voltage at the service compared to that of the other services? Aside from lighting, does it have much in the way of single-phase loads? Are the single-phase loads distributed in a balanced manner, or is there excessive voltage imbalance?
What about the surge protection in that building? Does it even exist? If so, is it staged protection, or is an attempt being made to get by on a single device at the service?
Since this is an interview, ask if the plant engineer can take you out to look things over. You may find, for example, ground rods installed at motors, which is typically a sign of improper bonding. Also, listen for transformer hum.
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.