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HV Current Transformer Selection Guide(1)

Protection & Measurement of HV Current Transformers


High Voltage Current Transformer

High Voltage Current Transformer

  1. Conditions of Use


1-1          25 ~ 40


≤1000 m

Seismic Intensity


Pollution Level

Indoor grade   ≤ 2 Level

Outdoor grade  ≤ 3 Level

1-1  Indoor Use: 

  • The environment air has no obvious dust, smoke and corrosive gas, steam or salt and other impurity;
  • The humidity conditions: 24 h the average relative humidity ≤ 95% less;
    High Voltage Current Transformer

    Used For Metering &Protection Current Transformers

  • Within 24 h of water vapour pressure is an average ≤ 2 kPa;
  • A month, the average relative humidity ≤ 90%
  • Within one month of vapor pressure on average ≤ 8 kPa

1-2  Outdoor Use:

  • During the period of 24 h, the measured average environment temperature ≤ 40 ℃
  • The sunshine radiation of 1000 W/m2 (sunny noon) should be considered;
  • The ambient air may be dust, smoke, corrosive gas, steam or salt;
  • Wind pressure ≤ 700 Pa (the equivalent of 34 m/s);
  • Should be considered a condensation and precipitation.

1-3  Special Conditions of Use (otherwise consider)

 2. Technical Characteristics
  • The manufacturing company name and location name or the name (export), and other marks, easy to identify manufacturing unit production serial number and date;
  • Transformer type and name, using standard code, measuring licensing logo and measuring license batch number;
  • The rated voltage and maximum voltage Um (for example, rated voltage 35 kV, the highest voltage 40.5 kV);
  • Rated frequency (for example: 50 hz);
  • The polarity relationship between the polarity: all marked terminals P1 and S1 and C1, with the same polarity in the same instant of time.
  • Rated current, the first rated current (example: 500 A), the secondary rated current (5 Aor 1 A),
  • The rated insulation level;
  • Rated voltage rating factor and the corresponding rated time;
  • Insulating heat level;
  • Performance parameters of the secondary winding;
  • Between the secondary winding and ground insulation rated short-time power frequency withstand voltage of 3 kV, and between the secondary winding of the insulation resistance shall be not less than 100 M Ω.
  • Winding turn-to-turn insulation should be able to withstand the rated short-time power frequency withstand voltage of 4.5 kV (peak).
    HV Current Transformers

    HV Current Transformers

  • Equipment types: indoor or outdoor;
  • Structure: oil-immersed or fully enclosed casting type
  • Instrument security coefficient, FS ≤10
  • Thermal stability and dynamic stability;
  • The thermal stability of current selection of the following (short circuit within the duration of 4 s):


  • Dynamic stable current for the thermal stability of current 2.5 times.
  • Rated output values:


HV Current Transformer Selection Guide(1)

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