ACR Electronics PowerWatch, Reference Manual, Page: 56 / 88

PowerWatch©
49
2007 ACR Systems Inc.
can occur on the hot-neutral lines or on the neutral-ground lines. Sags are
only measured on the hot-neutral lines.
Outage Events An Outage Event is a 0 voltage sag (for example, event #16
listed above).
High and Low Frequency Events Frequency events are recorded when the
frequency is outside the preset frequency thresholds.
Loss of Synchronization Excessive harmonics or noise on a power line
may cause severly distorted voltage waveforms. While not common, these
distorted waveforms could result in "extra" zero crossings on the AC line.
PowerWatch synchronizes itself to the consecutive positive and negative zero
crossings of the AC line (every 8.33 milliseconds). Should the voltage
waveform be so highly distorted that unexpected zero crossings are detected,
PowerWatch will report a loss of synchronization relative to the measured
voltage waveform.
Extreme Column
The Extreme column displays the maximum value measured during the event.
End Time/Duration/Degree Column
This column displays the duration of an event, or the time that the event
ended, or, in the case of a single impulse, the event's position on the sine
wave (in degrees).
Information is displayed according to the length of the event.
·
Events of less than one second are displayed in number of cycles.
·
Events of one to 119 seconds are displayed in seconds. Outages
up to 16 seconds are recorded in 0.5 cycle resolution, otherwise the
outage resolution is eight seconds.
·
Events of between two minutes and 24 hours are displayed in
hours, minutes and seconds for example, 07:51:24 (7 hours, 51
minutes, and 24 seconds).
·
Events that last longer than 24 hours display the end time (date and
time).
If an event was still in progress when data was downloaded from the VDR, the
event will be designated as an open event in this column. PowerWatch can
display one each of three open event types simultaneously. Open events are
assigned the number zero in the Event # column.
Ó 2007 , ACR Systems Inc.