Title :
A digital three-phase watthour meter
Author :
Seppa, H. ; Talja, P. ; Blomberg, O. ; Kallunki, M. ; Vehvilainen, S.
Author_Institution :
Metrol. Res. Inst., Tech. Res. Center of Finland, Espoo, Finland
Abstract :
A microprocessor-controlled three-phase digital watthour meter is described. The wattmeter is based on a sampling method and on an analog-to-digital (A/D) conversion; only one 10-b A/D converter, integrated in a microprocessor, is used. The resolution of the converter is improved by superimposing noise on current and voltage signals, and its uncertainty is reduced via an external resistive voltage divider. A wide current range is achieved by passing voltage signals. proportional to input currents, through a programmable-gain amplifier. The overall uncertainty of the meter is less than 0.1%. A block diagram of the wattmeter is presented.<>
Keywords :
analogue-digital conversion; computerised instrumentation; digital instrumentation; microcomputer applications; watthour meters; digital three-phase watthour meter; external resistive voltage divider; noise; programmable-gain amplifier; sampling; uncertainty; Analog-digital conversion; Calibration; Circuits; Microprocessors; Resistors; Sampling methods; Signal resolution; Voltage; Watthour meters; Wattmeters;
Conference_Titel :
Precision Electromagnetic Measurements, 1990. CPEM '90 Digest., Conference on
Conference_Location :
Ottawa, Ontario, Canada
DOI :
10.1109/CPEM.1990.110040
