30 5 WHAT THE 2SX-SERIES SCANNER RECORDS
The Flicker report is used both to confirm a customer complaint about
flickering lights, and to measure progress in mitigating a problem. If no Flicker
events were recorded, then no voltage variations occured which exceeded the
allowed limits, and the problem may have been solved. Since flickering light
perception is so subjective, merely showing a customer a Flicker report which
shows no flicker according to a standard curve may lessen the complaint by
showing that the voltage variations are within standard limits.
If Flicker memory is filled, Flicker recording stops. The amount of memory
used for Flicker is different for various Scanners, but every Scanner with Flicker
can record hundreds, and most over one thousand records.
Flicker is not meaningful on neutral to ground voltage channels: only
channels that are used to power lighting generate meaningful Flicker data.
Thus, flicker is only recorded for the line-to-neutral voltage channel on the
2SX-Series Scanner.
5.11 Abnormal Voltage
The Abnormal Voltage record type shows if the average line voltage moved
past a low or high threshold from the nominal voltage. On some Scanners,
the low threshold exceedence is indicated by a green LED on the front panel,
and the high threshold exceedence by a red LED. When the trigger occurs,
the event is timestamped to the nearest second. There is a separate LED and
report for each voltage channel.
5.11.1 Trigger Logic
The triggering logic uses a low and high threshold, a nominal voltage, and
a trigger duration. The thresholds are added and subtracted to the nominal
voltage to find triggering points. If the voltage crosses a triggering point for
longer than the trigger duration, an Abnormal Voltage event occurs.
The Scanner is initialized with a list of potential nominal voltages (such
as 120, 240, etc.), with low and high voltage thresholds for each. The actual
nominal is picked by the Scanner during the two minute countdown. The
average voltage during the countdown is compared to each of the nominals;
the closest one becomes the nominal voltage for the entire recording session.
There are five standard nominals in the software setup (120, 208, 240, 277,
and 480 volts), and two custom nominals. The custom nominals can be set
to any voltage. It is possible to enable and disable the standard and custom
nominals. For example, if you wanted to force the Scanner to use 230 volts
as the nominal, the standard nominals should be disabled, and both custom
nominals set to 230. If the standard nominals were not disabled, there would
