© 2008 Siemens Energy & Automation, Inc. All Rights Reserved.
ACCESS 9340 and 9360 Meters PMCM-9340D-0208
Chapter 4—Metering Capabilities 2/2008
EN–50
Input Metering Demand
The meter has five input pulse metering channels, but only one digital
input. Digital inputs can be added by installing one or more option
modules (9340-60-I/O26 or 9340-60-I/O2222). The input pulse
metering channels count pulses received from one or more digital
inputs assigned to that channel. Each channel requires a
consumption pulse weight, consumption scale factor, demand pulse
weight, and demand scale factor. The consumption pulse weight is
the number of watt-hours or kilowatt-hours per pulse. The
consumption scale factor is a factor of 10 multiplier that determines
the format of the value. For example, if each incoming pulse
represents 125 Wh, and you want consumption data in watt-hours,
the consumption pulse weight is 125 and the consumption scale
factor is zero. The resulting calculation is 125 x 10
0
, which equals 125
watt-hours per pulse. If you want the consumption data in kilowatt-
hours, the calculation is 125 x 10
-3
, which equals 0.125 kilowatt-hours
per pulse.Time must be taken into account for demand data so you
begin by calculating demand pulse weight using the following
formula:
If each incoming pulse represents 125 Wh, using the formula above
you get 450,000 watts. If you want demand data in watts, the demand
pulse weight is 450 and the demand scale factor is three. The
calculation is 450 x 10
3
, which equals 450,000 watts. If you want the
demand data in kilowatts, the calculation is 450 x 10
0
, which equals
450 kilowatts.
NOTE: The meter counts each input transition as a pulse. Therefore,
for an input transition of OFF-to-ON and ON-to-OFF will be counted
as two pulses.For each channel, the meter maintains the following
information:
• Total consumption
• Last completed interval demand—calculated demand for the last
completed interval.
• Partial interval demand—demand calculation up to the present
point during the interval.
watts
watt-hours
pulse
----------------------------
3600 seconds
hour
-------------------------------------
×
pulse
second
-------------------
×=
To Next Page
Loading...
