As per IS: 2705:

• General particulars – 11 kV-33 kV
• Highest system voltage (HSV) – 12 kV (rms)-36 kV (rms)
• Power frequency dry/wet withstand voltage on primary winding for one minute – 28 kV (rms)-70 kV (rms
• Lightning impulse withstand voltage (1.2 x 50 ?s) – 75 kV (rms)-170 kV (rms)

• Rated transformation ratio as per customer requirement (in amp)
• Rated primary current – up to 2000 A
• Rated secondary current – 1 A, 5 A, 0.577 A
• Short time thermal current (Ith) – as per customer requirement, in general CT is to be specified with STF of 100 for 1 sec or STC (Ith) equal to the system fault level whichever is lower, KA (rms)
• Ith duration – 0.5 to 3.0 second
• Short time dynamic current – 2.5 x Ith kA (peak)
• Number of cores – up to 5 cores
• Output burden – up to 60 VA, 0.8 pf lagging
• Accuracy class – for metering 0.2S, 0.2, 0.5S, 0.5, 1.0 and 3.00, for protection 5P, 10P, 15P and PS;
• IAF, ALF, knee point voltage, exciting current and resistance – as per customer requirement /design constraints
• Type of construction – dead/bottom tank or live/top tank