Transforming Energy for America


Every transformer is tested prior to shipping using state-of-the-art equipment in accordance with customer specifications and the requirements of: IEEE/ANSI, CEI/IEC, CAN/CSA.

Large Power Testing Capability Features:

  • Test area able to accommodate extra-large power transformers and auto-transformers
  • Maximum Rating: 1,400 MVA 3Ø and 300 MVA 1Ø
  • HV Maximum Voltage: 765 kV
  • Maximum BIL: 2050 kV
  • Maximum Applied Potential: 500 kV 5A
  • In-house oil testing: DGA, moisture, PF, DBDV, IT, acid
Factory Acceptance Tests

Routine Tests:

  • Preliminary
  • Losses
  • Dielectrics
  • Control Wiring and CTs
  • Operation of Devices

Design / Other Tests:

  • Temperature Rise
  • Audible Sound Level
  • Single Phase Excitation

Special Tests:

  • Sweep Frequency Response
  • Overload Test
  • Overvoltage Test
  • Leakage Reactance
  • 1/3 Octave Band

Insulating Oil Analysis:

  • Moisture Content
  • Neutralization Number
  • Interfacial Tension
  • Color
  • Power Factor
  • Dielectric Breakdown
  • Dissolved Gases in Oil

Test Categories:

  • Preliminary Tests
  • Insulation Resistance of Windings
  • Magnetic Circuit
  • Insulation Power Factor and Capacitance
  • Windings
  • Bushings
  • Voltage-Turns Ratio
  • Winding DC Resistance


  • No Load Loss
  • Excitation Current
  • Load Loss
  • Impedance Voltage
  • Zero Sequence Impedance


  • Lightning Impulse
  • Switching Impulse
  • Applied Voltage
  • Induced Voltage with Partial Discharge Measurement


IEEE C.57 12 00, IEEE C.57 12 90, CSA 9

IEC 60076-01, IEC 60076-02, IEC 60076-03, IEC 60076-10

Medium Power Testing Capabilities

Routine tests as per IEEE C57.12.90-2015 performed on all transformers
  1. Transformation Ratio or Voltage Ratio
  2. Verification of the Vector Group by Turn Ratio Meter
  3. Winding Resistances Up to 50A
  4. Insulation Resistance Up to 10 kV Meggar
  5. Insulation Resistance to Ground for Core (up to 10 kV DC)
  6. Capacitance and Tan Delta as per Doble Method Up to 10 kV AC Voltage
  7. Lightning Impulse Withstand Test Up to 550 kV
  8. Applied Voltage Tests Up to 300 kV
  9. Short-Circuit Impedance and Short-Circuit Losses
  10. No-Load Loss and No-Load Current
  11. Induced Voltage Withstand Tests
  12. Partial Discharge at 1.58x of Rated for 1 Hour With Corona Detection (Class II Transformer)
  13. Control Function & Wiring
  14. Dissolved Gas Analysis
Special/Type/Optional Tests may be performed when requested as per IEEE C57.12.90-2015
  1. Temperature Rise Test
  2. Overload Temperature Rise Test
  3. Infra-Red Thermal Image
  4. Zero-Sequence Impedance on Three-Phase Transformers
  5. Switching Surge Impulse Test Up to 550 kV class
  6. Acoustic Noise Level
  7. Harmonics of the No-Load Current
  8. Sweep Frequency Response Analysis (SFRA) Doble5400
  9. Oil Breakdown Voltage
  10. PPM (Water Content in the Oil)
  11. Dew Point (Only “Routine” for Transformers Shipped Without Oil)

All of our plants keep records of all tests results, and certified test reports are provided to the customer for every transformer shipped.

Witness Testing Of Transformers

VTC welcomes hundreds of customers and consultants to our plants every year who personally witness the testing of their units. Customer rooms with wi-fi are available to work and relax during test transitions and employee breaks. Experienced test engineers and application engineers are available to walk customers through the plants explaining our processes and manufacturing equipment.