Varelen Electric Co., Ltd

Liquid Immersed Transformer

  • ♦oil immersed transformer use ester oil is that it is not flammable, superior fire safety
  • ♦Efficient transformer with reduced losses
  • ♦Reduce energy consumption 
  • ♦Green energy, sustainable
  • ♦C5 Marine coating
Liquid Immersed Transformer
oil immersed transformer
Liquid immersed transformers
Oil type transformer
hermetically sealed  transformer

Related product parameters

Why choose Varelen oil immersed transformer? Safe and environmental friendly transformers

1. Magnetic Core

The three-limb iron core is made of oblique cut Grain-oriented, seven-step silicon steel lamination insulated on both sides, guaranteeing low losses and low noise.  It is protected on the surface with a flash-proof varnish in order to prevent the sheet from corrosion and to reduce the noise.

2.Transformer winding

The winding as the centerpiece of the transformer must be especially protected  both against high electrical stress due to external over voltages and against mechanical overloads by short circuits. Huarui transformers are systematically designed to meet these requirements. The windings are made of copper or aluminum. Low-voltage windings are made of strip or flat wire, and the high voltage windings are manufactured from round or profile wire. (diamond-dotted paper) bonds the winding into a compact block while drying and increases the short-circuit capacity additionally.


Main Specification
Transformer Type Oil immersed
Rated capacity up to 25mva
Rated voltage up to 36kv
Frequency 50/60Hz
Phase 3 Phase
Winding material Copper /Aluminum
Tap changer Off-load or on-load
Vector group YNd1d1/ Dyn11

Ambient temperature

-20°C to +40°C
Dielectric fluids Mineral oil / Dimethyl Silicone/ FR3 oil /MIDEL 7131


Oil level gauge

Transformer tank

pressure relief valve

Tap changer

Oil Thermometer



oil immersed transformer drawing


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 specialized tests to meet all customer requirements. We make what matters work for our customers in a safe and reliable way.

distribution 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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