Gas-insulated (SF6) voltage transformers 110..750 kV

High-voltage inductive instrument voltage transformers (VT) of the JDQXF series are designed and intended for transmitting measurement information signals to measuring, protection, automation, alarm and control devices of AC electrical circuits in high-voltage networks from 110 to 245 kV with a frequency of 50 or 60 Hz. The operating principle of transformers is based on the phenomenon of electromagnetic induction. Voltage transformers (VT) are designed for a service life of at least 30 years (and with proper operation even more). The internal gas insulation (sf6) is hermetically sealed from air, and all external parts are made of corrosion-resistant material.

By design, voltage measuring transformers are of a reference type with a bottom arrangement of windings in a grounded metal case. The high voltage terminal is installed on the top of the insulating column of the transformer, and SF6 gas (sf6) is used as the internal insulating medium. Voltage transformers can have up to five secondary windings. Depending on the purpose, the voltage transformer windings are used for measurement and protection; depending on the customer’s needs, the secondary terminals of the voltage transformer can be manufactured for different loads and accuracy classes. The secondary terminals of the windings are located in a contact (terminal) box located at the base of the transformer. To prevent unauthorized access to the secondary windings, the terminal box cover located inside the terminal box is sealed. For safety, voltage transformers are equipped with valves to relieve excess pressure that may occur in emergency situations. To indicate the SF6 gas pressure in transformers, two-channel pressure gauges are provided.


  • Rated high voltage from 110 to 245 kV
  • Secondary circuit voltage 100/√3V, 110/√3V, 115/√3V, 120V*
  • Number of secondary windings up to 5
  • Accuracy class of windings for measurement 0.1;0.2;0.5;1;3;
  • Winding accuracy class for protection 3P; 6P
  • External insulation polymer
  • Gas level indicator
  • Ambient conditions: temperature -50° to +55°
  • Partial discharge level: ≤10 pC
  • Complies with IEC and IEEE standards or equivalent standards


Consistent accuracy throughout the entire service life.

  • No oil
  • Fireproof building structures.
  • Explosion-proof structures
  • Special designs provide environmental protection from the effects of ferroresonance.

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.

750kV 500kV 400kV 330kV 275kV 230kV 220kV 161kV 150kV 138kV 132kV 115kV 110kV 88kV 69kV 66kV 63kV 46kV 33kV High-voltage SF6 gas insulated voltage transformer, high- voltage instrument voltage transformer, HV SF6 VT. Voltage transformer