In Electrical System, sometime without identification of Phase Sequence it is impossible to proceed further. The Phase Sequence Indicator is used to determine the Phase Sequence R, Y & B of 3 Phase Voltage. It is important that Phase Sequence is known properly prior to energizing electrical motor & other equipment, as incorrect connection could cause damage to the equipment. The correct operation of measuring instrument like 3 Phase Energy Meter, 3 Phase Power Meter and Automatic Control of devices also depend on the Phase Sequence.