SF6 Gas Insulated Current Transformers.
The current transformer is SF6 gas insulation, inverted frame, with the top of T type aluminum case which there are secondary winding(s) and primary winding(s) inside. The bushing is composite materials with silicon rubber umbrellas or high strength porcelain. The secondary terminal leads which through the metal tube are connected with the secondary terminals box which at the base. There is a pressure relief device at the top of the case, when the pressure is more than 0.8MPa (1.0 MPa only for 500 kV) if the current transformer is discharge inside, the relief device will be broken to release the pressure and send an alarm information. There is a SF6 density monitor fix at the base, it can indicate the SF6 pressure which inside the current transformer (its indicated value is the SF6 pressure at 20℃), and it will provide an information when the SF6 pressure is drop down to the minimum service pressure of the current transformer, to remind the user replenish the SF6 gas to the rated pressure.
一、Service Conditions
a. Ambient air temperature: maximum 40℃, minimum -40℃, average value of the ambient air temperature does not exceed 30℃ measured during a period of 24h.
b. Altitude: The altitude does not exceed 1000m (this is the routine requirement, if there is any different requirement, we can provide the products with 2000m, 3000m, 4000m or 5000m altitude according to the clients’ requirements)
c. The average value of the relative humidity does not exceed 95% at 25℃ measured during a period of one month
d. The maximum wind speed does not exceed 34m/s
e. Earthquake intensity does not exceed 8 degree
f. There have to be no gas that may seriously affect the insulation and conductive ability of electric equipments, steam, ash, salt, chemical deposit, pollution and corrosive or explosive material.
二、Main Technical Parameters
4.1 Rated primary current is 50A~4000A
4.2 Rated secondary current is 5A or 1A
4.3 Rated frequency is 50Hz or 60Hz
4.4 Rate output 20VA~50VA (If any other rated output required, We can satisfy it.)
4.5 Accuracy class and t heir combinations: Steady accuracy classes are 0.2S, 0.2, 0.5S, 0.5, 5P, 10P, PR and PX;transient accuracy classes are TPS, TPX, TPY and TPZ. There are 1~6 pcs secondary winding(s) in a CT.
4.6 Rated operating pressure of the SF6 gas is 0.40MPa (0.50 MPa only for 500 kV); Minimum operating pressure of the SF6 gas is 0.35MPa (0.45 MPa only for 500 kV).
4.7 Instrument security factor (FS) of measuring class is 5 or 10.
4.8 Accuracy limit factor (ALF) of protective class is 5, 10, 15, 20, 30 or 40.
4.9 Rated continuous thermal current Icth is 1.2In.
4.10 For rated short-time thermal current Ith (r.m.s.) and rated dynamic current Idyn (peak).
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