Schneider Electric 4000 manual Demand Power Calculation Methods, April Demand Readings

63230-300-212	Chapter 4—Metering Capabilities
April 2001	Demand Readings

Demand Power Calculation Methods

Block Interval Demand

Demand power is the energy accumulated during a specified period divided by the length of that period. How the circuit monitor performs this calculation depends on the method you select. To be compatible with electric utility billing practices, the circuit monitor provides the following types of demand power calculations:

•Block Interval Demand

•Synchronized Demand

The default demand calculation is set to sliding block with a 15 minute interval. You can set up any of the demand power calculation methods from the display or from SMS. For instructions on how to setup the demand calculation from the display, see “Setting Up the Metering Functions of the Circuit Monitor” on page 16. See the SMS online help to perform the set up using the software.

In the block interval demand method, you select a “block” of time that the circuit monitor uses for the demand calculation. You choose how the circuit monitor handles that block of time (interval). Three different modes are possible:

•Sliding Block. In the sliding block interval, you 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 circuit monitor displays the demand value for the last completed interval.

•Fixed Block. In the fixed block interval, you select an interval from 1 to 60 minutes (in 1-minute increments). The circuit monitor calculates and updates the demand at the end of each interval.

•Rolling Block. In the rolling block interval, you select an interval and a subinterval. The subinterval must divide evenly into the interval. For example, you might set three 5-minute subintervals for a 15-minute interval. Demand is updated at each subinterval. The circuit monitor displays the demand value for the last completed interval.

Figure 4–3below illustrates the three ways to calculate demand power using the block method. For illustration purposes, the interval is set to 15 minutes.

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