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Current transformer CA (230 - 800 kV)

Outdoor, oil-filled top-core current transformer with oil-filled stainless steel bellows and paint-free housings

CA type outdoor rated oil-filled current transformers are based on a head type (top core) design. All our current transformers are built-to-order to customer specifications. CA current transformers can meet many applications for metering and protection with a number of dome sizes for up to six independent cores from 230 kV up to 800 kV. This current transformer is available with either porcelain or silicone rubber insulators, with ANSI 70 gray porcelain insulator considered as the standard product. Hermetic sealing of the design is accomplished using a stainless steel bellows to prevent free-breathing outside moisture-laden air, and also allows the unit to ship in the horizontal position.

The CA has demonstrated reliable performance in service with a very low field failure rate that is much lower than the industry average. This design has been installed all over the western hemisphere from desert to arctic climates.


  • Revenue metering
  • Control
  • Indication
  • Relay protection

Why Hitachi Energy?

For revenue metering and protection in high voltage networks, the oil-paper insulated current transformer CA has a long, reliable service reputation in the industry and is versatile for meeting the most demanding applications.  Hitachi Energy offers our users unique advantages as follows: 

  • Excellent application engineering support to ensure optimum solutions 
  • Designed for diverse environmental conditions
  • Designs specific to critical applications such as wide range metering, capacitor bank monitoring and other demanding uses
  • Head type design allows for higher current application without special coolers and expense 
  • Short primary transition in the dome lends itself to high short-circuit capability
  • 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 230 - 800 kV
Max. primary current  Up to 5,000A
Short-circuit current Up to 123 kA/1 sec
Insulators Porcelain (silicon rubber SIR optional)
Creepage distance ≥ 25 mm/kV (longer on 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 all IEEE metering and protection classes
(0.3%, 0.15%, C100, C200, C400 and C800)

IEC also available on request

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