Oil insulated Current Transformers

IOSK oil paper insulated rent trsansfrrent transformers are of the head type. Each unit is designed in accordance with the latest IEC and IEEE/ANSI standards.

General Features

  • Excellent insulation stress control using a fine graded bushing (less weight, less oil volume, increase safety and reliability)
  • Maintenance free
  • Safety (strong limitation of internal overpressure, shielded secondary windings, hermetically sealed)
  • Special core class ratings TPS, TPX, TPY and TPZ are available
  • Low reactance bar-type primary permits high short circuit currents and high primary current
  • Essentially unaffected by stray external magnetic fields
  • Excellent seismic performance due to optimized designs (low weight) and porcelain (cementing) and flanges (welding)
  • Exclusive use of corrosion resistant materials (aluminum base and head)



  • Available from 40.5 kV up to 550 kV
  • High quality mineral oil insulation, PCB free, biological decomposition
  • Porcelain or composite insulator
  • Hermetically sealed stainless steel metallic bellows
  • Head type design – low primary losses, low weight and minimum oil volume
  • Rated primary currents up to 5000 A
  • Rated secondary current 0,5 A to 5 A
  • Maintenance free during a long lifetime of more than 30 years
  • High accuracy CT (0.1 %) over wide extended range of primary current
  • Uniformly distributed secondary windings guarantee accurate transformation at both rated and high currents
  • Explosion resistant by
    • High reliability insulation system
    • Fine graded bushing
    • Bushing tube and connection to withstand high short circuit current
    • Shielded secondary windings