User's Manual

74 Demand Metering
You can switch which type of calculation will be performed. If energy usage decreases
because of forward and reverse configuration, the present demand is calculated to be 0.
 Previous Demand. Previous demand is the demand value for the last complete or partial
demand interval. The previous demand is updated every time a sub-interval expires, and
the demand value returned represents the accumulated energy for the main interval
divided by the interval time.
 Maximum (Peak) Demand Maximum demand is the largest demand value
calculated since the last demand reset. At every sub-interval for rolling
demand or at every main interval for block demand, the previous demand
value (i.e. the maximum demand calculated for the previous interval) is
compared with the maximum value calculated for the present interval (i.e.
the interval that has just elapsed). If the previous maximum demand value is
greater than the present maximum demand value, the maximum demand for
the present interval will be updated to be the value of the previous maximum
demand value. In this way, the maximum value will be kept as each interval
(or sub-interval) passes.
In this way, the maximum demand is an average power calculation over the
configured interval of time. The beginning and end of an interval are both
synchronized to the top of each hour. This average mechanism avoids
recording momentary spikes but catches general peaks in trends. At each
demand reset, the maximum demand is reset to 0. Each maximum demand value
is recorded with the corresponding date and time of occurrence.
 Cumulative Demand. Cumulative demand is the summation of all previous maximum
demand values that were present at the time of their respective demand resets. At each
demand reset, the cumulative demand is incremented with the value of the new maximum
demand.
 Continuous Cumulative Demand. Continuous cumulative demand is the summation of
cumulative demand and the maximum demand value since the last demand reset.
Continuous cumulative demand is correctly calculated if cumulative demand is disabled
and continuous cumulative demand is enabled.
 Coincident Sources. The meter can store up to two coincident values, chosen from the
available measured and calculated values, along with each maximum demand value.
When the maximum demand values are updated, the coincident values are also updated at
the same time.
Demand Resets
A demand reset marks the end of a demand billing cycle. The following tasks are
performed for each demand reset:
 Update all calculations evaluated at demand reset.
 Save the current demand values to previous (latest) demand reset table and
historical demand reset table. The meter can hold one or more copies of
demand reset data before the oldest data is overwritten. This figure is user-
configurable.
 Reset current maximum demand and coincident values.
Demand resets can be scheduled into the meter with NES System Software, or with
the Provisioning Tool. Resets can be configured to occur daily, weekly, monthly, or at
any other daily interval up to once every 63 days (i.e. every second day, every third
day, and so on). The exact time of the reset is configurable. If the meter is powered