28 5 WHAT THE 2SX-SERIES SCANNER RECORDS
Another possibility is a voltage sag where the current during the event is
lower than the pre-trigger current (or about the same), and the post-trigger
current is about the same. Here, the monitored load probably did not cause
the event. Some other load pulled the voltage down, and the monitored load
current dropped proportionately with the lowered voltage. When the voltage
came back up, the current rose to its normal level also.
Winscan groups closely occurring Event Change records into super-events.
A super-event is started when an Event starts on any channel. The super-event
lasts until there are no running Events on all channels for at least an entire
second. A complicated voltage disturbance may trigger several closely spaced
or back-to-back Event Changes, but will be grouped into a single super-event
for easier analysis.
Event Change is recorded separately for each voltage channel. If Event
Change memory is filled, Event Change recording stops. All voltage channels
use the same Event Change memory. The amount of memory used for Event
Change is different for various Scanners, but every Scanner with Event Change
can record hundreds, and most over one thousand records.
5.9 Power Outage
The Power Outage report lists the date and time of all outages during the
recording session. An outage is defined by the Scanner to be a voltage sag
below 80 volts, lasting for at least 1=3 of a second. Only channel one’s volt-
age is used to trigger an outage. The beginning and end of the outage are
time-stamped. In the report, the duration is also given, along with the total
number of outages and the total outage time.
If the Scanner has battery ride-through capability, it will continue to record
Histograms, Stripcharts, etc. during the outage. If there is no battery, or if the
battery runs down, the Scanner loses power and stops recording. When power
is restored, the Scanner records the end of that power outage and resumes
recording normally.
A power outage often triggers Waveform Capture, which may help reveal
the cause of the outage.
5.10 Flicker
The Flicker record type is designed to show voltage variations that cause lights
to flicker. The Scanner defaults to the threshold of irritation curve from IEEE
Standard 141. This curve is designed to show only voltage flicker that is
perceived as irritating. When this occurs, a flicker event is recorded with the
