Siemens ACCESS 9340 - Demand Power Calculation Methods; Block Interval Demand

© 2008 Siemens Energy & Automation, Inc. All Rights Reserved.
PMCM-9340D-0208 ACCESS 9340 and 9360 Meters
2/2008 Chapter 4—Metering Capabilities
EN–45
Demand Power Calculation Methods
Demand power is the energy accumulated during a specified period
divided by the length of that period. How the meter performs this
calculation depends on the method you select. To be compatible with
electric utility billing practices, the meter provides the following types
of demand power calculations:
• Block Interval Demand
• Synchronized Demand
• Thermal 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 ION Setup. See the ION Setup online help to perform
the set up using the software.
Block Interval Demand
In the block interval demand method, you select a “block” of time that
the meter uses for the demand calculation. You choose how the
meter 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 meter
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 meter
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 meter displays the demand value for the last completed
interval.
Figure 4–4 below illustrates the three ways to calculate demand
power using the block method. For illustration purposes, the interval
is set to 15 minutes.