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waveform can be determined using the vertical scale. If a harmonic analysis is displayed, the RMS
current is also listed.
When viewing current inrush logs, the highest ½ cycle RMS level of each event is displayed. An event
starts when the inrush trigger is exceeded and ends either when 10 cycles have passed or when a ½
cycle does not exceed the trigger level (whichever is longer). Current dip logs display the lowest ½
cycle RMS level of each event. Each event starts with the trigger and ends in 10 cycles or when a ½
cycle does not fall below the trigger level (whichever is longer).
When viewing swell/sag RMS graphs, the RMS of each ½ cycle is graphed and the most extreme
measurement, with its timestamp, is presented at the top.
When viewing transient waveforms, the instantaneous values of the current are graphed, as with
consumption waveforms. But the summary value at the top is the Ipk value above the trigger, with its
timestamp.
If trending data is being recorded and ATPOL II is operating in phase-neutral voltage measurement
mode, the average RMS current of each phase and neutral for each second will be displayed and
recorded each second. If in phase-phase voltage measurement mode, the average RMS current of
each phase for each second will be displayed and recorded each second.
The measurements of current presented on ATPOL II can also be displayed in PSM by using the
remote control feature.
In addition, our Report Generator software will present maximum, minimum, and average current of
each phase and neutral during any one or two intervals of time set by the user. If two time intervals are
chosen, it will report the percent change and the actual change between the two intervals. For
instance, if a comparison report is chosen and I
1
average is 48.0 A during the first interval and 47.8 A
during the second interval, then the report would show:
Before After Units Change
%
Change
Current, Phase 1, Avg.
48.0
47.8 amps
-0.2
-0.4%
The total harmonic distortion (THD) and K factor of currents is displayed using the THD function,
discussed later in this chapter.
Imbalance Measurements
In a perfectly balanced three phase system, the voltages are of equal magnitude and the currents of the
three phases are of equal magnitude. In most situations, however, the voltages and currents are not
balanced. An imbalance can be a nuisance or can actually cause damage, depending on the driven
load. Therefore it is important to measure voltage and current imbalance.
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