Schweitzer Engineering Laboratories SEL-734, Instruction Manual

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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
Sub
int
erv
a
l L
e
ng
th
(m
in
u
te
s
)
1 5 10 15 30 60
1 5 5 15 30
2 3 10 20
1 6 15
5 12
3 10
6
5
Table 4.3 Time = 5 Minutes Intervals
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
Table 4.4 Time = 10 Minutes Intervals (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