Allen-Bradley Powermonitor 3000 User Manual page 128

6-2 I/O Operations
Publication 1404-UM001D-EN-E - October 2004
Pulsed Control
Many electric energy meters provide a dry contact output that changes
state at intervals determined by a metered parameter. Pulsed control
lets the Powermonitor 3000 emulate this function. You may select the
following options for the Control source parameter:
1 = Watt-hours forward
2 = Watt-hours reverse
3 = VAR-hours forward
4 = VAR-hours reverse
5 = VA-hours
6 = Ampere-hours
Set the Output width to the desired pulse duration in milliseconds. Set
this parameter to zero (0) if you want the output to toggle instead of
pulse. This operation emulates the KYZ operation of
electromechanical energy meters. For a two-wire KYZ connection, use
only one side of the relay. For a three-wire KYZ connection, use both
sides of the Form C output.
In a two-wire interface, (KY connection), an output event occurs only
when the output contact closes. In a three-wire connection, an event
occurs when either the KY or KZ contact closes. Therefore twice as
many output events occur in a three-wire connection as in a two-wire
connection for the same number of relay transitions.
Set the Output scale for the number of increments of the Control
source parameter it takes to pulse or toggle the selected output.
Follow these suggested steps to calculate the output scale:
1. Determine the maximum value of the selected parameter
expected in an hour period. This is related to the feeder
capacity. For example, a 480 volt, 1200-ampere three-phase
feeder can supply approximately 100 kW or 100 kWh per hour.
2. Divide this maximum parameter value by 3,600 to determine the
maximum value expected per second. In our example, we
round this to 280 Wh per second.
3. Select a maximum pulse rate. This should be between 2 and 5
pulses per second for a two-wire KYZ connection and between
2 and 10 pulses per second for a three-wire connection. Let's
use a three-wire KYZ connection and a pulse rate of 4 pps.
4. Compute the output scale by dividing the result of (2) by the
result of (3) and rounding to the nearest integer. For our
example, we'll set the output scale to 70.