Varelen Electric Co., Ltd

Oil Filled Transformer

Easily adopt to the grid, easy connection process

Low noise solution

Oil Filled Transformer
fluid immersed transformer
Oil cooled transformers
oil immersed transformer solutions

Related product parameters

Main Specifications
Transformer Type oil imemrsed type 
Rated power up to 20mva
Rated voltage up to 36kv
Frequency 50/ 60Hz
Phase single or three phase
Oil preservation Hermetically Sealed/ Conservator/ Free Breathing
Tap changer off-load or on-load
Winding material Aluminum/ Copper
Cooling ONAN /ONAF
Dielectric liquids Mineral oil / Dimethyl Silicone/ FR3 oil
Vector groups Dyn11, Yyn11 (according to customers requirements)
Coolers corrugated wall or radiator


Oil level gauge

Transformer tank

pressure relief valve

Tap changer

Oil Thermometer




For each transformer are prepared and issued a test report, in accordance with IEC 60076.  except for routine tests, we also offer type tests and specialised tests to meet all customer requirements. We make what matters work for our customers in a safe and reliable way. 

oil immersed transformer testing

Routine test

  •  Measurement of winding resistance
  •  Measurement of voltage ratio and check of phase displacement
  •  Measurement of short-circuit impedance and loss
  •  Measurement of no-load loss and current
  •  Dielectric routine tests
  •  Tests on on-load tap-changers, where appropriate
  •  Leak testing with pressure for liquid-immersed transformers(tightness test)
  •  Tightness tests and pressure tests for tanks for gas-filled transformers
  •  Check of the ratio and polarity of built-in current transformers
  •  Check of core and frame insulation for liquid immersed transformers with core or frame insulation


 Type test

  •  Temperature-rise type test
  •  Dielectric type tests
  •  Determination of sound level for each method of cooling for which a guaranteed sound level is specified
  •  Measurement of the power taken by the fan and liquid pump motors
  •  Measurement of no-load loss and current at 90% and 110% of rated voltage

 Special Test

  •  Dielectric special tests
  •  Winding hot-spot temperature-rise measurement
  •  Determination of capacitances windings-to-earth, and between windings
  •  Measurement of dissipation factor(tanδ) of the insulation system capacitances
  •  Determination of transient voltage transfer characteristics
  •  Measurement of zero-sequence impedance(s) on three-phase transformers
  •  Short-circuit withstand test
  •  Measurement of d.c. insulation resistance each winding to earth and between windings
  •  Vacuum deflection test on liquid immersed transformers
  •  Pressure deflection test on liquid immersed transformers
  •  Vacuum tightness test on site on liquid immersed transformers

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