Transformer maintenance consists mostly of testing, although it includes other activities (e.g., housekeeping-related). The three categories of transformer testing are:

1. Acceptance. Normally, you perform acceptance tests following initial installation. The test results provide baseline maintenance data. But if a transformer has not operated for a while, it requires acceptance testing again. The normal definition of "a while" is three days or more, but you might use a shorter timeframe if conditions warrant (e.g., the sprinkler system operated).

2. Routine. These are data collection activities, such as recording temperatures, and don’t require de-energization.

3. Periodic. The complete menu of these tests requires a deep skill set, and thus they are typically outsourced to a testing firm.

In the next several parts of this series, we'll examine these further.