Allen-Bradley 1404-M4, User Manual

Page: 170 / 356

Publication 1404-UM001D-EN-E - October 2004
8-20 Advanced Features
•
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