Voltage Transformer Testing

Testing Procedures

  • Insulation Resistance test.
  • Voltage Transformer Ratio & Polarity test.
  • Winding Resistance test.
Download: VT Test Format

Equipment Required

  1. CPC 100 for VT Ratio & Polarity test.
  2. Insulation Resistance tester: Megger mit1020. 
  3. Multimeter.
  4. Micro ohm meter: Drlo10
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CPC 100
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Insulation Tester
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Multimeter
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Micro ohm Meter

Insulation Resistance Test

  • Use Megger mit1020 to measure insulation resistance.
  • Insulation Resistance Tests to be done:
    • Primary winding - Ground      (Apply 1kV for 1 minute)
    • Primary winding - Secondary winding      (Apply 500V for 1 minute)
    • Secondary winding - Secondary winding      (Apply 500V for 1 minute)
    • Secondary - Ground      (Apply 500V for 1 minute)

VT Ratio & Polarity Test

  • Use Omicron CPC100 to test VT ratio & polarity.
  • ​Connection on CPC100 will be same as the shown figure.
  • Repeat the test for the other phases and the other secondary cores.

Winding Resistance Test

  • Use multimeter to measure the primary winding resistance (Normally in k ohm).
  • Use the micro ohm meter to measure the secondary winding resistance ( Normally in m ohm).