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Current transformer CXM (25 - 170 kV)

Intended for bi-directional metering over wide currents

Current transformer CXM is an oil-filled, top core design for bi-directional metering. The transformer has oil insulated shield-graded construction intended for outdoor installations.  A  gas cushion on top of the oil hermetically seals the unit to prevent free-breathing of outside moisture-laden air.  

The CXM has demonstrated excellent accuracy stability over the extremely wide current range (from 0.5 to 400% of nominal current), while also maintaining reliable performance in service with a low field failure rate which is below the industry average.  This high accuracy, wide current range design has been installed all over the western hemisphere, from desert to arctic climates, for metering wide load current swings with precision not available from standard current transformers.


  • Revenue metering for independent power producers for bi-directional power flows
  • Revenue or allocation metering for tie-points that can go through zero current
  • Extreme revenue metering accuracy for large critical loads

Why Hitachi Energy?

  • Hitachi Energy has some of the world's most extensive experience in offering high accuracy wide range metering current transformers, and have refined the design for best performance to meet demanding applications.
  • Excellent application engineering support to define the best ratio and continuous thermal current solution based on min. and max. currents to be accurately measured
  • Can supply the necessary high short-circuit strength for generation sites
  • Designed for diverse environmental conditions - from polar to desert
  • Ability to match various accuracy and design solutions - from critical applications to low current levels, all in the same accuracy class
  • Dielectrically stringent production includes hermetically sealed design with 100% partial discharge testing

Brief performance data

Installation Outdoor
Design Head (top core) type
Insulation Oil-paper
Highest voltage for equipment 25 - 170 kV
Max. primary current Up to 3,400 A (up to 170 kV)
Short-circuit current Up to 120 kA/1 sec
Insulators Porcelain (standard)
Silicon rubber (by request)
Creepage distance ≥ 25 mm/kV (longer by request)
Service condition  
  • Ambient temperature
40 ºC to +40 ºC (standard)
  • Design altitude
Maximum 1000 m (standard)
  *Other temperatures and altitudes are possible
Accuracy Meets and exceeds the IEEE C57.13 high accuracy metering and burdens 0.15sB1.8

IEC CI 0.2s also available on request

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