GE Grid Solutions Multilin 9450 - 2.7 Demand Integrators

CHAPTER 2: METER OVERVIEW DEMAND INTEGRATORS
EPM 9450/9650 ADVANCED POWER QUALITY METERING SYSTEM – INSTRUCTION MANUAL 2–9
Watt hour (Wh): N = number of samples
VAR hour (VARh): N = number of samples
2.7 Demand Integrators
Power utilities take into account both energy consumption and peak demand when billing
customers. Peak demand, expressed in kilowatts (kW), is the highest level of demand
recorded during a set period of time, called the interval. The EPM 9450/9650 supports the
following most popular conventions for averaging demand and peak demand: Block
Window Demand, Rolling Window Demand, Thermal Demand, and Predictive Window
Demand. You can program and access all conventions
concurrently with the GE Communicator software (see the GE Communicator Instruction
Manual).
Block (Fixed) Window Demand:
This convention records the average (arithmetic mean) demand for consecutive time
intervals (usually 15 minutes).
Example: A typical setting of 15 minutes produces an average value every 15 minutes (at
12:00, 12:15. 12:30. etc.) for power reading over the previous fifteen minute interval (11:45-
12:00, 12:00-12:15, 12:15-12:30, etc.).
Rolling (Sliding) Window Demand:
Rolling Window Demand functions like multiple overlapping Block Window Demands. The
programmable settings provided are the number and length of demand subintervals. At
every subinterval, an average (arithmetic mean) of power readings over the subinterval is
internally calculated. This new subinterval average is then averaged (arithmetic mean),
with as many previous subinterval averages as programmed, to produce the Rolling
Window Demand.
KFactor
hRMS
RMS
x
h
x
h
h
h








2
1
127
2
1
127
Wh
W
t
sec hr
t
N



()
/
3600
1
VARh
VAR
t
sec hr
t
N



()
/
3600
1