Allen-Bradley Powermonitor 3000 User Manual page 170

8-20 Advanced Features
Publication 1404-UM001D-EN-E - October 2004
• Auto-threshold set margin: range 1.0 to 100.0 per cent, default
20.0
• Voltage trigger threshold: range 0.1 to 1000.0, default 10.0
• Current trigger threshold: range 0.1 to 1000.0, default 10.0
Threshold Configuration
The Powermonitor 3000 compares voltage or current transients against
a threshold that you may set manually or command to be set
automatically. You select either voltage channels or current channels
with the Detection mode parameter.
When you issue the Auto-threshold set command, the Powermonitor
3000 first determines if there is sufficient signal amplitude on the
selected voltage or current channels to set the threshold. If the signal
amplitude is greater than 10% of full-scale, the Powermonitor 3000
begins timing the Auto-threshold set duration. During this time, it
monitors the selected channels, calculates an average transient index,
and decrements the Auto-threshold duration time remaining
parameter. At the end of this time, it combines the average transient
index with the Auto-threshold set margin and stores the result as the
Voltage trigger threshold or Current trigger threshold.
Threshold settings relate to both magnitude and duration of a
transient, so they are representative of the energy contained in a
transient. In most cases, use the automatic threshold calculation as a
starting point, by issuing an Auto-threshold set command. Then
manually adjust the selected threshold if you want to increase or
decrease the sensitivity.
The Powermonitor 3000 will not monitor for or capture transient data
until a threshold setting has been configured.
Reading Transient Analysis Metering Data
The Powermonitor 3000 M8 model presents 12 cycles of transient
metering results for each of up to 6 transient captures in Table A.44.
Transient analysis metering data is not available via Modbus
communications. This read-only table of 14 floating-point elements
contains the following metering results and capture statistics:
• Capture number: transient capture number associated with the
metering results. Range 1 to 6
• Cycle number: which cycle in the capture is returned in this
read. Range 1 to 12