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As most utilities perform DC resistance tests on Busbar and switchgear which has CTs within the test loop, and because you are applying DC current to the primary, the level of magnetization occurring is actually a Volt Seconds affect. You have 1 turn and the voltage across that turn has a...

A Canadian manufacturer, Rex Manufacturing located in the Toronto area does make large resin cast trasformers up to 10 MVA, and they do perform all the standard ANSI tests including PD as part of the full testing regiment. They have been in business for quite a while and so have some decent...

The principle of using a reference capacitor with a HV Insulation PF Test Set (Doble is your term) is not comlex. The first step has the test set measuring the reference capacitor and recording the capacitance value (many times, one records this value once and imprints it on the capacitor for...

This is an often asked question in the electrical maintenance field. As a provider of test equipment (we are a competitor to Doble) and with 30 years of testing experience, "Doble" (PF Insulation) does not give consistent results on dry type transformers. I have seen insulation PF of 5% on a new...

PD is typically a factory test which is difficult to replicate as a field test because of the sensitivity of the measurement (5pC is a very small amount). A high voltage or medium voltage station emits tremendous noise, all of which is seen by PD measuring equipment. I have sold Biddle PD...

When one determines a test voltage for a this type of test, one should know that the test you performed is an insulation resistance test. This is a quality determination test, which should not change dramatically with voltage, unless you approach the maximum voltage spec of the cable. In your...