Switchgear and Transformer Testing

At NPD we have an extensive background in switchgear testing and fault investigations. We offer a range of tests including IR, AC withstand testing, DLA/ DDF testing and PD testing. Recent studies in the UK have suggested that up to 85% of all disruptive failures in HV insulation are related to partial discharge activity. It follows that partial discharge testing is now recognised as a vital test to determine the condition of HV insulation and prevent eventual catastrophic failure, especially with less tolerant materials such as polyurethane and epoxy. Using these results we can give guidance on where to concentrate maintenance or replacement of parts, which will reduce cost and time waste due to uneccessary maintenace or replacement of switchgear which may have years of life to come. We can also offer contact resistance testing, CB trip timing and oil analysis as part of our maintenance packages.

We can perform transformer diagnostic tests including DDF on bushings (C1. C2 tests), winding DDF, winding IR, winding polarisation index (PI), DC ratio and resistance and oil analysis.

Switchgear tests:

  • Offline partial discharge testing
  • DLA/ DDF testing
  • Power frequency withstand tests
  • Insulation resistance
  • Contact resistance
  • Minor maintenace

Transformer tests:

  • DDF bushing testing C1 and C2
  • DDF winding tests HV to LV
  • Winding insulation resistance and polarisation index
  • Oil analysis
  • Current transformer primary HV tests (CT)
  • Voltage transformer primary HV tests (VT)