Instrument voltage transformers (VT) NMTSM are designed to transmit measurement information signals to measuring instruments, protective devices, automation, signaling and control in voltage networks from 3.3 to 42 kV AC with a frequency of 50 or 60 Hz and.

NMTSM voltage measuring transformers are designed for outdoor installation. The advantage of this series of transformers is the long creepage distance (up to 31 mm/kV), which allows these transformers to be used in the most polluted places.

According to the principle of operation, they are inductive, single-phase, single-pole, grounded. Voltage transformers (VT) have a cast housing made on the basis of an epoxy compound. The insulation material of voltage transformers has excellent arc, ozone and ultraviolet protection characteristics, while it has high mechanical strength, so that the transformers can work for more than 30 years without any maintenance. The creepage distance and discharge distance of NMTSM voltage transformers are designed for high levels of air pollution.

Additionally, measuring voltage transformers, at the request of the customer, can be equipped with a ferroresonance protection device.


  • Rated primary voltage from 3.3 to 42 kV
  • Rated secondary voltage 100.100/√3, 110.110/√3 ,120.120/√3
  • Number of secondary windings up to 3
  • Winding accuracy class for measurement 0.2; 0.5
  • Winding accuracy class for protection 3P;6P
  • Voltage factor 1.5 or 1.9
  • Ambient conditions: temperature from -45° to +55°
  • Compliance with IEC and IEEE standards or equivalent standards


  • Lack of any maintenance throughout the entire period of operation
  • Fire and explosion-proof design
  • Long creepage distance
  • Possibility of installation in any plane
  • High loads for all accuracy classes
  • Low partial discharge (PD)
  • Resistance to aggressive environmental conditions
  • The hydrophobic material exhibits excellent outdoor performance and also minimizes the possibility of arcing.
  • No ozone depleting gases

Voltage transformers (VT) of the NMTSM series were developed for operation at transformer substations, at traction substations of railways, hard-to-reach objects where equipment maintenance is not required, at enterprises with high pollution of electrical equipment.

Transformers meet the requirements of IEC, ANSI, IEEE, GOST standards.

Measuring voltage transformers NMTSM are a good alternative to obsolete and obsolete current transformers with oil insulation.

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