How do CT and PT work in the energy measurement?
Current Transformers (CT) and Potential Transformers (PT) are used to lower the magnitude of the current and voltage to be measured. Say 100Amp current is flowing in a circuit and you want to measure it. If you connect an ammeter to measure the current the ammeter has to be built to handle that current. Or say if you want to measure current and voltage in a high voltage circuit at 220kV, you need properly insulated meters to withstand that voltage. The meters will be very big for that purpose. The CT and PT is used to solve this problem. The CT and PT works on the principle of transformer and lowers the current and/or voltage at a lower value which can be safely and easily measured. For energy measurement connect the CT and PT secondary to the terminal of the energymeter. However you need to select the proper CT and PT and if you are measuring 3phase power you need to connect the CT and PT as per the requirement.
