Combined CT/PT Units


Instrument transformer includes Voltage Transformer & Current Transformer put together in a tank. Combined Instrument Transformer converts distribution class voltage & current to standardized low & easily measurable values which are used for metering for revenue purposes.

When operating the current transformer between 5% of the rated current and the rated continuous thermal current, the voltage transformer shall not exceed the limits of voltage error and phase displacement corresponding to its class

within the specified range of burden and between 80% and 120% of the rated voltage.

Similarly when operating the voltage transformer between 80% of rated voltage and the rated voltage multiplied by rated voltage factor, the current transformer shall not exceed the limits of current error and phase displacement within the range of current corresponding to its class at any value from 25% to 100% of rated burden.

The Combind Instrument Transformer unit is specially designed to provide consistent accuracy over the entire range of current and voltage by calibrated design of built in CT and PT.

Skipper make Combined Instrument Transformers (11 to 33 kV) adhere to the requirements of the quality standards and our quality systems are certified as per ISO 9001-2000. These products are type tested for impulse voltage, short circuit and wet voltage withstand tests at internationally accredited laboratory ERDA in India.


Design Features:

Skipper has made combined instrument transformer both for indoor & outdoor purposes.

Medium Voltage Combined CTPT Units for Outdoor Purpose:

  • Single coil design located in corrosion proof tank
  • Vacuum Impregnated oil paper insulation for coil
  • Mineral & synthetic oil free of PCB
  • Stable accuracy over life time
  • Hermetic sealing & oil expansion by nitrogen cushion
  • In accordance with latest IS:2705 & IS:3156 standards,as well as IEC recommendations
  • Built for long lasting life with very little maintenance required

Sectional View :

ORDERING DATA: The following parameters need to be specified in order to design the product suited to customer specifications:

  • Reference standard
  • Rated Voltage
  • Basic Insulation Level (BIL)
  • Test Voltage
  • Rated Primary Current
  • Rated Secondary Current
  • Rated Primary Voltage
  • Rated Secondary Voltage
  • No.of Secondary winding
  • Classes/ Burden
  • Rated continuous thermal current
  • Rated short-time thermal current
  • Frequency
  • Climatic condition