In order to perform PF tests on transformer oils and fluids with the PF test
set, a special cell is provided with the test set. The cell is essentially a capacitor
which utilizes the insulating liquid as the dielectric. In order to make
this test, a sample of the insulating fl uid or oil should be obtained from the
transformer by opening the sample valve. Remember to fl ush approximately
one-quart of oil or fluid into a bucket to clean any contaminants from the
valve housing. Once this is done, then fi ll cell with oil sample to just above
the raised center of the cell to prevent any sparking due to insuffi cient
amount of oil. This cell holds approximately one-quart of fl uid. Make connections
of the cell as shown in Figure 3.15. The test voltage should be 2.5
or 10 kV depending upon the PF test being used. The test voltage should be
raised gradually to the desired level. Readings should be taken, and PF
value calculated in the normal manner as is done with the solid insulation