Loss Measurement on Complete Equipment/Schering Bridge with Faraday Cage

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Loss Measurement on Complete Equipment/Schering Bridge with Faraday Cage

  • It is used to measure dielectric loss.
  • It is particularly suitable for the insulation specimen whose one side is permanently earthed.
  • There are two methods subjected for such measurements.

(A) Inversion of the ‘Schering bridge using Faraday cage.
(B)  Use of artificial earth fully screened bridge.

(A) Inversion of the Schering bridge using Faraday cage

H. V. Bridge with Faraday Cage
Figure A
  • This bridge is used on high voltages.
  • Faraday’s cage houses, ratio arm, operating device and null-detector at very high potential.
  • There is provision of high insulation to the cage for the full test voltage with a neat design.
  • Only difficulty is in inverting physically the high voltage standard capacitor CN. So it is to be provided with mounting on fully insulated platform.

(B) Use of artificial earth fully screened bridge

  • This is useful only on low voltages.
  • Not successful if voltage is 5 kV or more.
  • Screening H.V. lead becomes essential.
  • In this measurement an artificial earth is employed.
  • This artificial earth differ in potential from a true earth by the voltage developed across each of the low voltage the low voltage arms of the bridge. This is shown in the figure below.
Artificial earth, fully Screened Bridges
Figure B

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