63230-300-212 Chapter4—Metering Capa bilities
April 2001 DemandReadings
57
© 2001 Schneider Electric All Rights Reserved
Demand poweris the energy accumulated during a specifiedperiod divided
byt helength of that period. How the circuit monitor performsthis calculation
dependson the method you select. Tobe compatible withelectric utility billing
practices,the circuit monitor provides the following typesof demandpower
calculations:
•Block IntervalDemand
•SynchronizedDemand
The defaultdemand calculation is set to sliding block with a 15 minute
interval. Youcan set up any of the demand powercalculation methods from
the display or from SMS. For instructionson how to setup the demand
calculationfrom the display, see “Setting Up the MeteringFunctions of the
Circuit Monitor”on page16. See the SMS online help to perform the set up
using the software.
In the blockinterval demand method, you select a “block”of time that the
circuitm onitoruses for the demand calculation. Youchoose how the circuit
monitor handlesthat block of time (interval). Three differentmodes are
possible:
•Sliding Block. In the sliding blockinterval, you select an intervalfrom 1 to
60 minutes (in 1-minuteincrements). If the interval is between 1 and 15
minutes, the dem and calculati on
updatesevery 15 seconds.Iftheinterval
is between 16and 60 minutes, the demand calculation
updates every60seconds. The circuit monitordisplays the demand value for the last
completed interval.
•Fixed Block. In the f ixed block interval, you select an in terval from 1 to 60
minutes (in 1-minuteincrements). The circuit monitor calculatesand
updates the demand at theend of each interval.
•RollingBlock. In the rolling block interval,you select an interval and a
subinterval. Thesubinterval must divide evenly into the interval. For
example,you might set three 5-minute subintervals for a 15-minute
interval. Demandis
updated at each subinterval. The circuitmonitor
displaysthe demand value for the last completed interval.
Figure4–3 below illustrates the threeways to calculate demand powerusing
the blockmethod. For illustration purposes, the interval is set to 15 minutes.
Demand Power
CalculationMethods
BlockInterval Demand