Tests on transformers are regulated by IEC 60076-11 standards and are divided into ROUTINE, TYPE and SPECIAL tests.


  • measurement of winding resistance
  • measurement of voltage ratio and check of phase displacement
  • mesurement of short-circuit impedance and load loss
  • measurement of no-load loss and current
  • separate-source AV withstand voltage test
  • induced AV withstand voltage test
  • partial discharges measurement
  • dimension check



  • lightning impulse test
  • temperature-rise test
  • sound level measurement



  • short circuit resistance test
  • winding hot-spot temperature-rise measurements
  • determination of capacitances windings-to-earth and between windings
  • measurement of dissipation factor (tan δ) of the insulation systems capacitances
  • measurement of zero-sequence impedance (s) on three-phase transformers
  • short-circuit withstand test
  • measurement of d.c. insulation resistance between each winding to earth and between windings
  • measurement of frequency response (Frequency Response Analysis or FRA); the test procedure shall be agreed between manufacturer and customer
  • detection of harmonic content in no load current
  • thermographic detection of hot-spots
  • in-rush surges test
  • test on vibration floor (seismic)