IEC/TR 61869-103:2012(E) is applicable to inductive and electronic instrument transformers for use with electrical measuring instruments for measurement and interpretation of results for power quality parameters in 50/60 Hz a.c. power supply systems. It gives guidance in the usage of HV instrument transformers for measuring the following power quality parameters; power frequency, magnitude of the supply voltage and current, flicker, supply voltage dips and swells, voltage interruptions, transient voltages, supply voltage unbalance, voltage and current harmonics and interharmonics, mains signalling on the supply voltage and rapid voltage changes.