Electrical Troubleshooting Quiz — March 2, 2021
Everything that Line Seven can produce gets sold, so any downtime is revenue lost forever. The line has been upgraded many times since it was installed a decade ago.
A few years ago, it started losing control cards and other electronics inside its main control cabinet. The turnaround on replacing some components was three weeks if no spares were in stock.
In one run of particularly bad luck, all spares of a control module were used within 48 hours. Consequently, an overheat protection function was added. It shuts down the unit and alerts maintenance. This still meant downtime, so a cooling fan was added. The fan created a dust accumulation problem in the cabinet, so an intake filter and a thermal switch were added.
The cabinet recently began a series of overheat protection shutdowns. Can you solve this?
Cabinet cooling touches on many issues. Find answers to these questions:
- Is ambient temperature high enough to reduce effective cooling, or can a source of cooler air be ducted in?
- Does the filter have sufficient flow-through rate?
- With all the modifications, have things been installed in a way that provides a poor air circulation path inside the cabinet?
- Does the fan supply adequate airflow to achieve the desired cooling?
You also need to check:
- Branch circuit power supply. Low voltage, harmonic distortion, and other power quality problems can cause heating.
- DC power source(s) in the cabinet. Check inputs and outputs using a scope.
- Poor terminal connections and failing components. Perform an infrared scan to see what is emitting the heat.
- Bonding. Is undesired current flowing through metal parts, heating them up?
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.