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Doc# E151701 12-7
12: Meter Calculations
Electro
Industries/GaugeTech
™
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12.2: 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 Nexus® 1262/
1272 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 CommunicatorPQA® software (see the
CommunicatorPQA
®
,
MeterManagerPQA
®
, and EnergyPQA.com
®
Software User 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 subinter-
vals. 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.
Example: With settings of 3 five-minute subintervals, subinterval averages are com-
puted every 5 minutes (12:00, 12:05, 12:15, etc.) for power readings over the previ-
ous five-minute interval (11:55-12:00, 12:00-12:05, 12:05-12:10, 12:10-12:15,
etc.). Further, every 5 minutes, the subinterval averages are averaged in groups of 3
(12:00. 12:05, 12:10, 12:15. etc.) to produce a fifteen (5x3) minute average every 5
minutes (rolling (sliding) every 5 minutes) (11:55-12:10, 12:00-12:15, etc.).
Summary of Contents for Nexus 1262
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