Measurement of tgδ and C of single-phase electrical apparatus with capacitive insulation under operating voltage

The authors describe a method of measuring tgδ (loss tangent) and C (capacitance) of a single-phase apparatus with capacitive insulation by using an ordinary Schering bridge which takes the secondary voltage of a same-phase power transformer as the voltage of the standard arm and suppresses interference. Examples are given to illustrate how to analyze the results of measurement. The proposed method is safe and reliable, since testers need not come into contact with the high-voltage side of the apparatus, and a series of safety measures are taken. Because errors and interference are eliminated, the measuring data is stable and the accuracy high