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Combined current/voltage transformer type KA

Outdoor, oil-filled, substation class wound type single phase metering unit

KA outdoor rated substation class oil-filled current/voltage transformers are wound type single phase metering transformers intended for revenue metering. These current/voltage transformers are built-to-order to customer specifications. KA transformers can meet many revenue metering applications with up to four independent cores from 46 kV up to 245 kV. This combined housing is available with ANSI 70 gray porcelain insulator considered as the standard product, with silicone rubber (SIR) polymer as an option. Hermetic sealing of the design is accomplished using a fatigue resistant stainless steel bellows on the dome to prevent free-breathing outside moisture-ladened air.

The KA provides reliable performance in service due to the conservative insulation system used at the lower distribution voltages.


  • Revenue metering
  • Check or indication metering

Why Hitachi Energy?

For revenue metering on critical loads, this conservative oil-paper insulated current/voltage transformer is extremely reliable for this application with the same reliability service record as the separate current and voltage transformers. The stable accuracy performance provides 0.3 percent accuracy metering for many revenue installations. Given the flexible construction, the design is very adaptable for meeting the most demanding applications. Hitachi Energy offers our users unique advantages as follows:

  • Excellent application engineering support to ensure the optimum solutions
  • Designed for environmentally diverse conditions
  • Designs specific to critical applications for single phase revenue metering
  • Distribution style format offers durable self-healing oil insulation for lower voltage use
  • Dielectrically stringent production features hermetically sealed design with 100% partial discharge testing

Brief performance data

Installation Outdoor
Design Wound type (top core CT and line to ground connected inductive VT)
Insulation Oil-paper
Highest voltage for equipment 46 - 245 kV
Maximum primary current Up to 4,000 A & up to 2,000/1200:1 VT ratios
Short-circuit current Up to 120 kA/1 sec & VF=1.9x-8Hrs
Insulators Porcelain (silicone rubber SIR optional)
Creepage distance ≥ 25 mm/kV (longer on request)
Service condition  
  • Ambient temperature
-40ºC to +40ºC (standard)
  • Design altitude
Maximum 1000 m (standard)
  *Other temperatures and altitudes are possible
  •  CT
Meets all IEEE wide range high accuracy metering class (0.3% or 0.15%)  

IEC CI 0.2s on request  

(4000A maximum)
  •  VT
Meets IEEE 0.3%ZZ and 3000VA thermal

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