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PowerLogic™ PM5100 series user guide Chapter 8—Measurements and calculations
© 2014 Schneider Electric All Rights Reserved 63
IEEE mode
In IEEE mode, the PF sign is determined by the type of load (inductive or capacitive)
contributing to the reactive power component of apparent power. PF sign is positive (+)
for capacitive loads (leading power factor). PF sign is negative (-) for inductive loads
(lagging power factor).
Related topics
• To change the HMI mode, see “Setting up regional settings” on page 35.
• To learn how the meter calculates power factor, see “Power factor” on page 61.
Demand
Demand is a measure of average consumption (typically power or current) over a fixed
programmed time interval.
The meter measures instantaneous consumption and can calculate demand using
various methods.
Related topics
• For instructions on configuring demand using the front panel, see “Demand setup”
on page 40
Power demand calculation methods
Power demand is calculated by dividing the energy accumulated during a specified
period by the length of that period. How the power meter performs this calculation
depends on the method and time parameters you select (for example, timed rolling
block demand with a 15-minute interval).
To be compatible with electric utility billing practices, the power meter provides the
following types of power demand calculations:
• Block interval demand
• Synchronized demand
• Thermal demand
You can configure the power demand calculation method from the front panel or using
ION Setup.
Block interval demand
For block interval demand method types, you specify a period of time interval (or block)
that the power meter uses for the demand calculation. Select/configure how the power
meter handles that interval from one of these different methods:
• Timed Sliding Block: Select an interval from 1 to 60 minutes (in 1-minute
increments). If the interval is between 1 and 15 minutes, the demand calculation
updates every 15 seconds. If the interval is between 16 and 60 minutes, the
demand calculation updates every 60 seconds. The power meter displays the
demand value for the last completed interval.
• Timed Block: Select an interval from 1 to 60 minutes (in 1-minute increments). The
power meter calculates and updates the demand at the end of each interval.
• Timed Rolling Block: Select an interval and a subinterval. The subinterval must
divide evenly into the interval (for example, three 5-minute subintervals for a
15-minute interval). Demand is updated at the end of each subinterval. The power
meter displays the demand value for the last completed interval.