User's Manual

Demand Metering Theory of Operation
5-6 Theory of Operation TM-iX0A-0805
Outage Recognition
The meter can detect temporary interruptions in service. For Demand calculations, meters
without Real-Time-Clocks (RTCs) “recognize” all interruptions in service as outages. Meters
with RTCs can be configured to only “recognize” outages if they last more than the configured
number of seconds. The Outage Recognition Time is configurable using iConFig.
Demand Forgiveness Time
Demand Forgiveness Time is the configured amount of time immediately following a recognized
power outage that Demand calculations are suspended. The Demand Forgiveness Time is
configurable using iConFig.
Self Read
During a Self Read, the meter captures the current billing data and then stores it in the associated
Self Read registers.
Self Reads are events that can be configured to be:
• Scheduled to occur at specific times or intervals
• Performed when other events occur (i.e., during a Demand Reset)
• Performed when triggered by an external command
Coincident Values
Coincident demand refers to a demand value that occurs at the same time as another demand
reaches its peak value. For example, an electric utility may want to record the kVAR demand at
the time of a maximum kW demand. This requires that kVAR demand be stored and reported
during the same interval as the maximum kW demand. Similarly, coincident power factor refers
to a power factor that occurs at the same time as a demand value reaches its peak value. For
example, an electric utility may want to record the average power actor at the time of a
maximum kVAR demand. This requires the average power factor be stored and reported during
the same interval as the maximum kVAR demand.
Primary/Secondary Metering
Primary Metering applies to transformer rated meters. Measured energy values are scaled
according to the current transformer (CT) and primary transformer (PT) ratios of the current
and/or voltage transformers connected to the meter. The resultant values reflect the energy as if
the meter was on the primary side of the transformers.
With Secondary Metering, the energy values are not scaled (i.e., the actual energy flowing
through the meter is measured).