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CHAPTER 1: AC POWER MEASUREMENT CONSUMPTION, DEMAND AND POOR POWER FACTOR
EPM 5300 SERIES ADVANCED POWER METERS – INSTRUCTION MANUAL 1–5
1.3 Consumption, Demand and Poor Power Factor
CONSUMPTION:
W = instantaneous power T = time in hours
The total electric energy usage over a time period is the consumption of WH.
Typically, the unit in which consumption is specified is the kilowatt-hour (KWH): one
thousand watts consumed over one hour. Utilities use the WH equation to determine the
overall consumption in a billing period.
DEMAND: Average energy consumed over a specified time interval. The utility determines
the interval, typically 15 or 30 minutes. The utility measures the maximum demand over a
billing period. This measurement exhibits a deviation from average consumption, causing
the utility to provide generating capacity to satisfy a high maximum consumption demand.
The highest average demand is retained in the metering system until the demand level is
reset.
POOR POWER FACTOR: Results in reactive power consumption. Transferring reactive
power over a distribution network causes energy loss. To force consumers to correct their
Power Factor, utilities monitor reactive power consumption and penalize the user for Poor
Power Factor.
T W=WH ×