IEC 60688:2012 applies to transducers with electrical inputs and outputs for making measurements of a.c. or d.c. electrical quantities. This International Standard is intended to specify the terminology and definitions relating to transducers whose main application are in industry; to unify the test methods used in evaluating transducer performance; and to specify accuracy limits and output values for transducers. The output signal may be in the form of an analogue direct current, an analogue direct voltage or in digital form. In this case, that part of the transducer utilized for communication purposes will need to be compatible with the external system. This standard applies to measuring transducers used for converting electrical quantities such as current, voltage, active power, reactive power, power factor, phase angle, frequency, harmonics or total harmonic distortion, and apparent power to an output signal. This standard is not applicable for instrument transformers that comply with IEC 60044 series; transmitters for use in industrial process applications that comply with the IEC 60770 series; performance measuring and monitoring devices (PMD) that comply with IEC 61557-12.