ITRON Centron, Техническое справочное руководство

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Operation: C12.19 C1SD, C1ST, and C1SL Versions
CENTRON® Meter Technical Reference Guide 51
The following quantities can be selected for thermal demand: W d, W r, W net, and W uni.
The thermal demand option has only one demand interval available. This interval length
(response time) is 15 minutes. When you enter into Test Mode, this interval length is fixed
at one minute.
Thermal demand is not available if TOU is enabled.
Cumulative Demand Values
Cumulative Demand is the summation of previous maximum demands after each demand
reset. When a demand reset occurs, the maximum demand values are added to the existing
corresponding cumulative demand values, and the sums are saved as the new cumulative
demands. These values will not increase until the next demand reset. This feature not only
protects the user from false or erroneous readings, but also provides the customer with extra
security against tampering. Cumulative demand may be used for block, rolling, and thermal
demand types.
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. For thermal demand
types, the previous demand value is equal to the present demand.