Inductive voltage instrument transformers 35..420 kV

Measuring inductive voltage transformers (VT) with paper-oil internal insulation of the VEOT series are large-scale voltage converters and are designed to transmit a signal of measuring information to devices for measuring, protecting, automatic, signaling and controlling electrical circuits in a network with a voltage of 35 to 420 kV. They have one primary and up to 6 secondary windings for measurement and protection.

Voltage transformers (VT) are insured for a term of operation of at least 30 years (and for the sake of proper operation, more) without any maintenance. The oil is hermetically insulated against a stainless steel bellows knot, and all external details are made of corrosion-resistant material.

By design, measuring voltage transformers (VT) are of the base type with the lower windings in a metal case. The primary winding is made of high quality copper wire, the interlayer insulation is made of oiled paper. The windings are insulated with oil-paper insulation and placed in an oil-filled tank. At the top of the insulating column is the primary winding terminal in an alloyed aluminum housing with an oil conservator.

The outputs of the secondary windings of the voltage transformer are placed in a terminal box located on the housing at the base of the transformer and closed with a sealed cover. A plate with technical data is attached to the cover of the secondary terminals. The working position of transformers in space is vertical.


  • Rated primary voltage from 35 to 420 kV
  • Rated secondary voltage 100/3.100/√3, 110/3.110/√3 ,120/3.120/√3
  • Number of secondary windings up to 6
  • Winding accuracy class for measurement 0.2; 0.5
  • Winding accuracy class for protection 3P;6P
  • Voltage factor 1.5 or 1.9
  • Oil expansion with stainless steel bellows
  • External insulation porcelain or polymer
  • Oil level indicator
  • Ambient conditions: temperature from -45° to +55°
  • Compliance with IEC and IEEE standards or equivalent standards


  • High quality oil-paper insulation
  • Minimum amount of oil
  • High seismic resistance of the structure
  • Hermetically sealed stainless steel oil expansion compensators, which ensures complete tightness of the transformer.
  • Resistance to external magnetic fields
  • Consistent accuracy over time
  • Anti-corrosion materials
  • Does not require maintenance for a long period (at least 20 years)
  • Minimum amount of oil
  • High fire and explosion safety

The description contains the characteristics of transformers that are produced in series. By agreement with the customer, it is possible to manufacture non-standard transformers.