CT is classified into Class 0.1, Class 0.2 (standard transformers) and Class 0.5, Class 1.0 and Class 3.0 (general transformers) by non-error (straightness) and phase angle change rates, and is used for Electronic Integrated Power Meter (0.2 to 1.0), Electronic Motor Protection Relay (EOCR, EMPR) and other current sensors (1.0 to 3.0) according to precision