For Current transformers the tolerance for each class is as follows:

For class 0.5s, if:
I < 0.01 x In - Percentage ratio error 1.5%
0.01 x In < I < 0.05 x In - Percentage ratio error 0.75%
0.05 x In < I < 0.20 x In - Percentage ratio error 0.5%
0.20 x In < I < 1.00 x In - Percentage ratio error 0.5%
1.00 x In < I < 1.20 x In - Percentage ratio error 0.5%

For class 1, if:
I < 0.05 x In - Percentage ratio error 3%
0.05 x In < I < 0.20 x In - Percentage ratio error 1.5%
0.20 x In < I < 1.00 x In - Percentage ratio error 1.0%
1.00 x In < I < 1.20 x In - Percentage ratio error 1.0%

For more information please refer to the standards IEC 61869-2 (2102)

Released for: Schneider Electric Ireland