GE MOTOR MANAGEMENT RELAY 469, Инструкция по эксплуатации

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GE Power Management 469 Motor Management Relay 4-75
4 SETPOINT PROGRAMMING 4.12 S11 MONITORING
4
The 469 measures motor demand for several parameters (current, kW, kvar, and kVA). These values may be
of interest for energy management programs where processes may be altered or scheduled to reduce overall
demand on a feeder.
Demand is calculated in the following manner. Every minute, an average magnitude is calculated for current,
+kW, +kvar, and kVA based on samples taken every 5 seconds. These values are stored in a FIFO (first in, first
out) buffer. The buffer size is dictated by the setpoint demand period. The average value of the buffer is calcu-
lated and stored as the new demand value every minute. Demand for real and reactive power is only positive
quantities (+kW and +kvar).
where: N = programmed Demand Period in minutes,
n = time in minutes
Figure 4–21: ROLLING DEMAND (15 MINUTE WINDOW)
Demand
1
N
----
Average
N
n 1 =
N
∑
=
TIME
0
20
40
60
80
100
120
140
160
t=0 t+10 t+20 t+30 t+40 t+50 t+60 t+70 t+80 t+90 t+100
MAGNITUDE