Electricity and thermal meter linearising correction circuit - has analogue-to-frequency converter and nulls and differentiates pulse rate

摘要

A correction circuit for electricity and heat meters with electronic measurement arrangements is for linearisation of arrangements performing multiplication (3) or differencing, conversion of analogue to pulsed digital signals and counting. It enhances the measurement reliability by avoiding the effects of offset and drift. During a monitoring mode one or more input values or derived signals are manually or automatically nulled and the analogue to frequency converter (7) pulse rate stored. During the subsequent measurement phase the measurement pulse rate is nulled. The measurement path output (fm-fo) is the difference of the measurement (fm) and nulled (fo) pulse rates. Alternatively, two parallel identical measurement paths are used. One is operated in monitor mode and the other in measurement mode.