User's Manual

Operation: Base Metrology
20 CENTRON® OpenWay™ Meter Technical Reference Guide
Continuous Cumulative Demand Values
Continuous Cumulative Demand is the sum of the maximum demand and the cumulative
demand at any point in time. At the end of each demand interval, if a new maximum
demand is reached, continuous cumulative demand will also be adjusted to reflect this new
maximum demand value. A demand reset will clear the maximum demand value, but will
not affect the continuous cumulative demand. Continuous cumulative demand may be used
for block, rolling and thermal demand types.
Present Demand
Present Demand is the value that would be used if an EOI were to occur when the data is
being viewed. It is calculated by dividing the accumulated energy in the current interval by
the time of a full interval. For block demands, present demand starts at zero for each interval
and ramps up to the demand value at the EOI. For rolling demands, the energy from the
oldest subinterval is discarded and the present demand is calculated using the energy in the
remaining subintervals and the energy in the current subinterval. At the beginning of a new
subinterval, it drops by the demand of the oldest subinterval and ramps up to the demand
value at the next EOI.
Present demand is not affected by a demand reset.
Previous Demand
Previous Demand is the demand from the most recently completed demand interval. When a
demand interval ends, the present demand is transferred to the previous demand. When
using rolling demand, this quantity is updated after each subinterval.
Peak Demand (Maximum Demand)
Peak Demand is the largest demand value that has occurred during any demand interval
since the last demand reset. At the end of a demand interval, the present demand is
compared with the current maximum demand register. If the present demand is greater, it is
transferred to the maximum demand. The maximum demand is reset to zero on a demand
reset. The date and time of the maximum demand are also recorded. Maximum demand is
used for block, rolling, and thermal demand types.
Demand Thresholds
The table below describes parameters that define the configuration of demand thresholds. A
threshold is a value against which a meter quantity is compared. If the quantity is beyond
the threshold, an alarm is generated.
Draft