Question

c) The circuit diagram for a Schering Bridge is shown in Figure Q4c is used to make measurements on a sample of insulation at 50 Hz. Both ends of the sample and the standard capacitor are connected to the high voltage side of the bridge. At balance conditions, the following readings were recorded; R3 = 10002 C2 = 500 pF, R4 = 2002, C4 = 223 nF. i) Calculate the tand of the sample dielectric. ii) Calculate the parallel equivalent capacitance and resistance of the sample dielectric. iii) If a voltage of 2 kV is applied across the sample dielectric, calculate the power loss in the sample dielectric.

Answer 1

AL the Bridge Balance, ZiZ4 Za Zz 2z = Read Let Z = r+ w WC Zu RH 1 + juGuru From 0: (v+ zhve) (it Jucariu iwa (iuca) (e+ jucx)(u) = (Swe) (14 junky) iwc, Ry – w CzRucr imaginary jwcR3 - wcCurs Ry De - By comporting Yeal and parts on both sides CoRy = CR, >> C= C. RH = 500 200 loco PF CICO PF WERY - *4:54 laco 223 X 10 V = R3 500 X LO 446 k-2 * For parallel RC combination : - WRC Wrc Loss tangent (tans) = :) 94(50) x 096 x to'xOTO 1.3 tane CSI with comme

1) C = 100 pF. Y = 446k 2 for V= 2kv (rms) Powerloss in the dielectric Sample = V° (2xFc). Tons (2000) (2000) x 26 x 50 x 100 x 10 x 9137 Press 8 968 W CS scanned with CamScanner