Do you have the expertise to properly conduct the tests needed to make good maintenance decisions? If not, these are some common areas of error that will crop up:

  • Ground testing. This often results in useless information due to erroneous testing procedures. One common mistake is conducting three-point ground testing with the utility power connected, thus bringing the neutral into the measurement. The results have no validity for the purposes of ground testing.
  • Motor testing. What's burning up windings or causing electronics to fail? Sticking a DMM on motor drive output terminals won't give you a complete picture. For that, you need a power analyzer as well as training so you know what to look for and what you're looking at when you find it.
  • Breaker condition. Few facilities have the in-house expertise to correctly, safely, and efficiently ascertain breaker condition. Study the manual for any big breaker, and you'll see why.
  • Harmonics evaluation. A harmonic analyzer or power analyzer can provide useful data. But do you know the conditions under which some data means more than other data or what actually constitutes an actionable problem?

We'll look at a solution to these problems in our next issue.