Method for repetitive measurement of the electrostatic charging tendency of liquid dielectrics

The construction of an apparatus for the measurement of the electrostatic charging tendency (ECT) of a dielectric liquid is described. A sealed reciprocating piston arrangement permits a liquid to be repetitively passed through a charge separating element. The use of a gold element is shown to minimize the effects of moisture and control temporal effects. The system is evaluated by testing samples of transformer oil drawn from the field. In general, the new system ranks the oils in the same way as a conventional assessment against a paper filter, although anomalies have been found which are an impediment to adoption.