Current Transformer

The outdoor type 25kV current transformer (CT) is used for installation in 132/ 25kV Railway traction sub-station for operation of protective devices, metering and indication purpose. It fully complies with RDSO specification number ETI/ PSI/ 90 (06 95).

The current transformer is suitable for outdoor use and performs well in moist, tropical climate and in areas subject to heavy rainfall, pollution, marine atmosphere and severe lightening.

Skipper manufactures Current Transformers as per RDSO specifications which are capable of withstanding

heavy vibrations with rapidly varying time periods in the range of 15ms to 70ms and with amplitude in the range of 30 micron to 150 micron and instantaneous peak going up to 350 micron.

These current transformers used in the railway traction system find application in feeder and transformer protection.

Feeder Protection: Following protections are possible with Skipper RDSO current transformers

  • Distance protection
  • Wrong Phase coupling protection
  • Instantaneous over current protection
  • Telemetry of feeder current
  • Telemetry of maximum demand
  • Telemetry of power factor
  • Restricted earth fault protection
  • Over current protection

Transformer Protection

  • Overcurrent protection
  • Restricted earth fault protection

All Skipper, railway application, 25kV current transformers comply to IS:2705

Constructional Features:

The current transformer has a single core with wound primary. The windings are made up of copper. The primary winding is split into two sections insulated from each other and suitably terminated as per the specifications so as to facilitate the change of transformation ratio by making series or parallel configurations as stipulated with the help of suitable links of suitable section made up of copper flat. Tapping on the secondary winding is are provided to match the transformation ratio requirements.

The core is built up of high permeability, low loss, cold rolled grain oriented, non ageing, electrical silicon steel laminations confirming to IS 3024.

The current transformer is of sealed construction with nitrogen cushion above the insulating oil to prevent any ingress of moisture.

The CT core and windings are dried suitably under vacuum to ensure the values of Insulation resistance and power factor as needed.