Commissioning / routine / diagnostic

Electrical test recommendations for transformers

A primary part of commissioning a transformer involves testing it after its installation in the field.  This amounts to a rigorous examination of the transformer intended to:

1) uncover problem(s), if any, with the transformer’s components, as a transformer is exposed to great stresses on its journey to site and is vulnerable to moisture ingress during installation and other unplanned maladies,
2) validate that the transformer tests the same as it did when last tested at the manufacturer’s facility,
3) establish a baseline with which to compare results of future tests.  For many tests, this will be almost essential to diagnose problems effectively in the future.

The electrical tests recommended for commissioning a transformer include:


Routine Screening

Transformers should be tested periodically through their lifetime.  However, limitless testing is not a good use of budget and manpower and not necessary.  Some tests are well suited as screening tools while others make sense only under suspicion of specific problems.  For example, unless there is reason to be concerned about winding deformation, a leakage reactance test is probably not necessary.

Megger provides thoughtfully equipped transformer test instruments for routine screening needs.  The electrical field tests recommended for routinely testing a transformer include:



The list of electrical tests that should be used to diagnose a transformer is all inconclusive.  Here it makes sense to intelligently choose, or at a minimum order, the tests to be performed based on symptoms of the transformer, operating and test history, etc.

Megger can help with this. The electrical field tests available to diagnose a transformer include: