CT accuracy is determined by its certified accuracy class which is stamped on the nameplate. eg, CT accuracy class of 0.3 means that CT is

certified to be accurate within 0.3 % of its rated ratio value for a primary current of 100 percent of the rated ratio.

 CT with a rated ratio of 200/ 5 with an accuracy class of 0.3 would operate within 0.45 % of its rated ratio value for a primary current of

100 amps i.e. for a primary current of 100A it is certified to produce a secondary current between 2.489 amps and 2.511 amps.

Accuracy is specified as a %age of range and is given for maximum burden as expressed in VA. The total burden includes the input resistance of the meter and the loop resistance of the wire and connections between CT and the meter. Example: Burden {{0}}.0 VA. Maximum Voltage drop=2.0 VA / 5 Amps= 0.400 Volts.

Maximum Resistance=Voltage / Current=04.00 Volts / 5 Amps=0.080 Ohms.

If input resistance of meter is {{0}}.010Ω, then 0.070Ω is allowed for loop resistance of wire, and connections between CT and meter.