Suppression of Noise and Elimination of Reflection Effect in Partial Discharge Measurements for Long Cables
1986 年 106 巻 5 号 p. 472-476
詳細
1986 年 106 巻 5 号 p. 472-476
Studies on the effectiveness of partial discharge detection circuit in noise suppression have been carried out for long cables. The new ballanced detection circuit with an electrooptical (E/O) converter and an optical fibre is compared with the conventional one using a coupling capacitor in series with the detection impedance. The new circuit detects discharge pulses differentially between symmetrically installed two cables at terminals, therefore most of the interfering noises are effectively reduced.
The effect of traveling discharge pulses reflected at the ends of long cables on discharge detection sensitivity can be evaded in the new circuit. This is confirmed at factory test when two parallel cables are connected through twice the characteristic impedance at the remote ends. The test results indicate nearly constant detection sensitivity, independent of the location of discharge in a long cable.
