Digital ac monitor

Apparatus for determining the value of a plurality of ac power parameters of a plurality of ac analog circuits each of which have separate analog electrical waveforms propagating in the circuit comprising:

• (a) sampling means for periodically sampling, during a first period of time for each circuit in succession, the analog current and voltage of the waveforms of each circuit a plurality of times during each cycle of the waveforms and over at least several cycles of the waveforms;
• (b) converting means for converting the ac current and voltage samples to digital signals proportional to the current or voltage value of the samples;
• (c) storage means for storing such digital signals;
• (d) computing means for calculating and averaging certain non-derived values of power parameters of the circuits directly from such digital signals during intervals between the taking of samples and storing such values, and, for adding the calculated values into running sums and storing said sums during a later time period for each circuit, and during a later period of time, averaging the stored sums selected for outputting;
• and
• (e) output means for interfacing said computing means with a data communications system whereby certain values can be selected for calculation and outputted.

The method of determining the value of a plurality of ac power parameters of a plurality of ac analog circuits each of which have separate analog electrical waveforms propagating in the circuit comprising the steps of:

• (a) periodically sampling, during a first period of time for each circuit in succession, the analog current and voltage waveforms of each circuit a plurality of times during each cycle of the waveform and over at least several cycles of the waveforms;
• (b) converting, during said first period of time, the ac current and voltage samples to digital signals proportional to the current or voltage value of the samples;
• (c) storing such digital signals during said first period of time;
• (d) calculating and averaging certain non-derived values of power parameters of the circuits directly from such digital signals during intervals between taking of samples and storing such values, and, during a second later variable time period for each circuit deriving the values of additional power parameters from such stored values and, for adding the calculated values into running sums and storing said sums during a third later time period for each circuit, and during a fourth later time period, averaging the stored sums selected for outputting.