The requirements of CT for the purpose of metering and protection are different. While for the metering purpose the accuracy within certain limits are very important where as in case of protection use, the CT should be able to give a reasonably proportionate secondary current for a variation of primary current which is many times the rated primary current. The Accuracy Load Factor (A.L.F) is the ratio of primary current upto which the CT gives reasonably proportionate secondary current to the rated current. A.L.F is a number which gives the idea that upto how many times of the rated primary current, the CT gives reasonably proportionate secondary current. It is very essential for protection purposes, which is the requirement at faulted system condition with large fault current.