Electrical measurements on circuits requiring current and potential transformers

Modern requirements make it necessary to measure alternating current, volts, and watts on circuits where the magnitude of these quantities and the safety of the operator require that some means be provided so that the instruments used are not directly connected to the circuit. In certain special measurements it may be found accurate and convenient to use resistances to multiply the indications of the instrument, these resistances being used as shunts to the current coil or in the potential coils of voltmeters or wattmeters.