32 5 WHAT THE 2SX-SERIES SCANNER RECORDS
voltage channel, as well as low and high thresholds. Only the first trigger for
each threshold is recorded.
5.11.3 Typical Settings and Suggested Uses
The Abnormal Voltage report is used to determine whether the voltage drifted
outside the thresholds during the recording session. Since the LED indicators
stay lit after a trigger, they can be used to see at a glance whether a Scanner
needs to be downloaded due to line voltage problems. Usually the Abnormal
Voltage report is used to get a quick read of whether there was any line voltage
drift- if so, then other record types such as the Stripchart and Significant
Change are used for more information.
The default threshold settings are at 5% and 10% of the nominal voltage
(for example, 6 and 12 volts for the 120 volt nominal). The high threshold
must be larger than the low threshold. The two custom nominals are preset
at 106 and 230 volts, but should be changed if a different nominal is in use.
The default trigger duration is five seconds, and can be set as small as one
second, or as large as 255 seconds.
5.12 Loose Neutral
The Loose Neutral report shows whether the typical symptoms of a loose
neutral have occurred. This report is intended for single phase services, with
voltage channels one and two connected from line to neutral. Only a two-
channel Scanner, or a Scanner set to use two channels, can record a Loose
Neutral. The symptom of a loose neutral condition is for one voltage leg
to rise in voltage, and the other to fall, with the sum of the two voltages
remaining close to twice the nominal voltage. For example, if the voltages
start at 119 and 121 volts, then move to 105 and 135 volts, a loose neutral is
a likely cause: one leg went up, one went down, and the sum is close to twice
the nominal (240 volts).
This happens when the load is not balanced, and the neutral is discon-
nected. If this condition is met for long enough, the Loose Neutral report is
triggered.
5.12.1 Trigger Logic
The Loose Neutral logic uses three parameters: duration, range, and differ-
ence. These parameters are used to judge whether one voltage leg has risen,
and one fallen, while the sum remained the same. The difference is a voltage
that specificies the minimum difference between the two legs. For example,
