Load Factor - Allen-Bradley Powermonitor 3000 User Manual

8-16 Advanced Features

Load Factor

Publication 1404-UM001D-EN-E - October 2004
The Powermonitor 3000 M6 and M8 models provide a Load Factor Log
which calculates and stores a group of plant demand metrics that
indicates how stable (or, conversely, how dynamic) a load is over a
period of time, usually one month. Use communications to configure
load factor operation and read the results. The Display Module does
not support an interface to the load factor log.
Load factor is the average demand divided by the peak demand for
the month. If the load is constant, load factor is 100%. The
Powermonitor 3000 calculate load factor for real, reactive and
apparent power and current, and stores the last 12 results in the Load
Factor Log in non-volatile memory. You may configure the
Powermonitor 3000 to automatically calculate and store load factor on
a particular day each month, or you may manually generate a
command using communications to save the load factor result and
reset the calculation. You will find information useful in reducing
peak demand when you look at load factor and peak demand values.
The peak demand period is stored in the Mix/Max Log, which has a
date and time stamp that indicates when the peak occurred. Using this
information, you may be able to identify plant activities that caused
the peak. You may be able to prevent or reschedule activities, or
install a demand management system. Either option may realize
significant savings in demand charges. You can use the load factor
values to estimate demand cost savings potential. The lower the load
factor, the higher the potential for savings by managing your electric
power demand.
The Powermonitor 3000 stores the load factor in 13 records. Record 0
stores in-progress calculations and will be cleared on a power cycle.
Records 1 through 12 are a first-in, first-out array saved in non-volatile
memory, with the highest record number containing the most recent
record. In manual clear/reset mode, when you issue a clear/reset
command, the contents of record 0 is written to the highest-numbered
record and (if necessary) the remaining records are shifted down, with
the oldest being deleted. In auto clear/reset mode, you select a day of
the month for this process to occur automatically.
Within each record, the Powermonitor 3000 stores peak, average and
load factor values for real power (watts), reactive power (VARs)
apparent power (VA) and average current (amps). Peak values are the
largest such value that has occurred since the last automatic or manual
clear/reset occurrence. The in-process record (record 0) is updated at
the end of each demand interval. If no demand interval has expired
since the last unit power-up, the record will return all zeroes.