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Electrical Troubleshooting Quiz — April 2, 2019

April 1, 2019
How to solve for the high rate of compression motor failures and thus reduce costly production interruptions

The plant air system periodically “goes down” (can’t maintain pressure) because one of the compressor motors fails. While the electricians are good at replacing the failed motors, the plant engineer wants you to solve the high rate of failures and thus reduce costly production interruptions.

He’s already checked the loading cycles, dryers, accumulators, and other items/issues that fall strictly under the compressor system itself. He’s even hired a contractor to use ultrasonics to find and fix leaks. He says all this work should eliminate from consideration that the compressor motors are just overworked.

What can you do to eliminate causes from your electrical perspective?

Start by checking the ventilation in the compressor room; louvers, fans, and filters are all failure points. Then, install temperature monitoring in the room and vibration sensors on the motors.

Next, look at the power supply. Compressor rooms are typically located along the perimeter because of noise. This means longer runs so check for voltage drop. Do you have all three phases and are their voltages in balance? If you have more than 2% voltage imbalance, bring it down. Conduct a power quality analysis; low power factor, excess third harmonics, and other issues can cause motor overheating.

Grounding in place of bonding means undesired current will flow through motor bearings. Thus, ensure you have a low-impedance equipment grounding conductor (EGC) [NEC Sec. 250.118], remembering it’s really an equipment bonding conductor. Ground rods at the motors do nothing.

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.

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