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Current Transformer IMB (36 - 800 kV)

Flexible design enables customer-tailored solutions

IMB oil-minimum current transformers are based on a tank type (hairpin) design and available with porcelain or silicone rubber insulators.

Hitachi Energy current transformers are tailor-made. The combination of different tank sizes, expansion systems, primary windings etc.,makes it possible to meet most customer requirements from 36 kV up to 800 kV.

More than 170,000 units have been delivered and installed all over the world - from desert to arctic climates by Hitachi Energy. Comprehensive service records show that the failure rate of IMB current transformers is up to four times lower than the industry average.


  • Revenue metering 
  • Protective relaying
  • System control and indication of power flow

Why Hitachi Energy?

  • For revenue metering and protection in high voltage networks, the oil-paper insulated current transformers IMB has the highest base in the world. 
  • Due to the low center of gravity, the IMB is very suitable for areas with high seismic activity. 
  • It is designed for a wide range of conditions, from polar to desert climate
  • The flexible tank type design allows large and/or many cores
  • The unique quartz filling minimizes the quantity of oil and permits a simple and reliable expansion system. The quartz filling also provides a mechanical support to the cores and primary winding. 
  • Hitachi Energy's vast experience and expertise enables in finding the optimum solutions as per site requirements.

Brief performance data

Installation   Outdoor
Design   Tank (Hairpin) type
Insulation   Oil-paper-quartz
Highest voltage for equipment kV 36 - 800
Max. primary current  A Up to 4000
Short-circuit current kA/1 sec Up to 63
Insulators   Porcelain
On request silicon rubber
Creepage distance mm/kV ≥ 25
Longer on request
Ambient temperature ºC 40 to +40
Design altitude m Maximum 1000 (Standard)
Others on request
Accuracy   Meets all IEC and IEEE metering and protection classes

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