4.8
SEL-734 Meter Instruction Manual Date Code 20090730
Metering
Demand Metering
DMSI-minute total. The rolling demand meter then averages a number of the
DMSI-minute totals to produce the rolling demand meter response. In the
Figure 4.3 example, the rolling demand meter averages the three latest
DMSI-minute totals because setting DMTC = 15 and DMSI = 5 (15/5 = 3).
The rolling demand meter response is updated every DMSI (5 minutes), after
a new DMSI-minute total is calculated.
The following is a step-by-step calculation of the rolling demand response
example in Figure 4.3 (bottom).
Time = 0 Minutes
Presume that the instantaneous energy has been at zero for at least 15 minutes
before “Time = 0 minutes” (or the demand meters were reset). The three
5-minute intervals in the sliding time-window at “Time = 0 minutes” each
integrate to zero.
Rolling demand meter response at “Time = 0 minutes” = 0.0/3 = 0.0 per unit.
Time = 5 Minutes
The three 5-minute intervals in the sliding time-window at Time = 5 minutes
each integrate into the 5-minute totals in Table 4.3.
Rolling demand meter response at Time = 5 minutes = 1.0/3 = 0.33 per unit.
Time = 10 Minutes
The three 5-minute intervals in the sliding time-window at Time = 10 minutes
each integrate into the 5-minute totals in Table 4.4.
Table 4.2 Demand Meter Settings and Settings Ranges
Interval Length (DMTC Minutes)
DMSI 1 5 10 15 30 60
Subinterval Length
(minutes)
1 5 10 15 30 60
1551530
2 3 10 20
1615
512
310
6
5
Ta b l e 4 . 3 Ti m e = 5 M i n ut e s In t e r va l s
5-Minute Totals Corresponding 5-Minute Interval
0.0 per unit –10 to –5 minutes
0.0 per unit –5 to 0 minutes
1.0 per unit
0 to 5 minutes
1.0 per unit total
Ta b l e 4 . 4 T i m e = 1 0 M i n u t e s In t e r va l s (Sheet 1 of 2)
5-Minute Totals Corresponding 5-Minute Interval
0.0 per unit –5 to 0 minutes
1.0 per unit 0 to 5 minutes
Courtesy of NationalSwitchgear.com
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