METHOD OF MONITORING INTERNAL PARTIAL DISCHARGES METHOD OF MONITORING INTERNAL PARTIAL DISCHARGES IN POWER TRANSFORMER AND APPARATUS FOR MAKING THE IN POWER TRANSFORMER AND APPARATUS FOR MAKING THE SAME SAME

摘要

PCT No. PCT/SE96/00558 Sec. 371 Date Dec. 6, 1996 Sec. 102(e) Date Dec. 6, 1996 PCT Filed Apr. 29, 1996 PCT Pub. No. WO96/35128 PCT Pub. Date Nov. 7, 1996In a method for monitoring of partial discharges in an electric power transformer (1) under normal operating conditions, the magnetic field at a high-voltage bushing (2) on the power transformer is sensed with an inductive sensor (6) comprising at least one coil (6a, 6b) arranged at the bushing, and the electric field at the bushing is sensed with a capacitive sensor (5). The output signals from said sensors are supplied to a signal processing unit (3) in which each one of the output signals is filtered in a separate bandpass filter (101, 102), whereupon the filtered output signals from said sensors are multiplied by each other. An output signal (PDI) from the signal processing unit is formed in dependence on the result of said multiplication for the purpose of detecting internal partial discharges in the transformer.