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Title: Digital ac monitor

An apparatus and method is provided for monitoring a plurality of analog ac circuits by sampling the voltage and current waveform in each circuit at predetermined intervals, converting the analog current and voltage samples to digital format, storing the digitized current and voltage samples and using the stored digitized current and voltage samples to calculate a variety of electrical parameters; some of which are derived from the stored samples. The non-derived quantities are repeatedly calculated and stored over many separate cycles then averaged. The derived quantities are then calculated at the end of an averaging period. This produces a more accurate reading, especially when averaging over a period in which the power varies over a wide dynamic range. Frequency is measured by timing three cycles of the voltage waveform using the upward zero crossover point as a starting point for a digital timer.
Authors:
 [1] ;  [2]
  1. (Natick, MA)
  2. (Lincoln, MA)
Publication Date:
OSTI Identifier:
866275
Report Number(s):
US 4672555
US patent application 06/662,392
DOE Contract Number:
AC02-76ET20279
Resource Type:
Patent
Research Org:
MASSACHUSETTS INST OF TECH
Country of Publication:
United States
Language:
English
Subject:
digital; monitor; apparatus; method; provided; monitoring; plurality; analog; circuits; sampling; voltage; current; waveform; circuit; predetermined; intervals; converting; analog; current; voltage; samples; digital; format; storing; digitized; current; voltage; samples; stored; digitized; current; voltage; samples; calculate; variety; electrical; parameters; derived; stored; samples; non-derived; quantities; repeatedly; calculated; stored; separate; cycles; averaged; derived; quantities; calculated; averaging; period; produces; accurate; reading; especially; averaging; period; power; varies; wide; dynamic; range; frequency; measured; timing; cycles; voltage; waveform; upward; zero; crossover; starting; digital; timer; voltage waveform; dynamic range; electrical parameter; wide dynamic; digital form; electrical parameters; predetermined interval /700/324/702/