HV Current Transformer Selection Guide(1)
Protection & Measurement of HV Current Transformers
- Conditions of Use
|1-1 25 ~ 40 ℃|
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;
- 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).
- 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: