Electrical Testing
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Tip of the Week: Power Quality, Part 2

If you think you may have problems related to equipment failure, here are steps to take to begin addressing some of the issues.

If you suspect power quality problems that are due to equipment failures and other symptoms, how do you respond? It is unlikely you have the required expertise in house, and you probably have to go through a process before you can bring in a firm with that expertise.

While that process is in progress, what can you do to start addressing at least some of these issues?

• Perform voltage measurements on all feeders, then on all branch circuits. Measure line to ground and line to line, RMS. You’re looking for low voltage, high voltage, and voltage imbalance. The sheer scope of the work may require hiring an electrical services firm. While awaiting approval, take the measurements for your critical equipment.

• Inspect for grounding and bonding errors. If you see a ground rod on the load side, that’s a red flag that something is wrong. This rod serves no electrical purpose, and is probably substituting for proper bonding.

• Check all transformers (except auto-transformers) for proper grounding; the National Electrical Code (NEC) considers them to be separately derived sources.

One way to turbocharge this process is to start keeping a spreadsheet of the problems as they occur if they seem related to power quality.

If you note key information, you can sort in a way that will enable you to conduct a Pareto analysis. This will, for one thing, reveal patterns that can lead to quicker resolution.

Include these fields:

• Whether the supply is a branch circuit or feeder.

• Nominal voltage.

• Building or area where load is situated.

• Affiliated production line, if applicable.

• Type of equipment served (use standardized codes, such as 1 for production motor with drive, 2 for production motor without drive, 3 for lights, 4 for HVAC, 5 for computers, etc.).

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