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 (k) When did the minimum power factor occur? What caused it?
(1) How does the power factor compare with the one on which the previous
power bill was based?
(m) What is the voltage drop between the main power bus and the various
major consumers.
If the profile peaks radically at only a few points, then demand leveling
could lead to a reduction in demand charges. An exception to this may exist
because of peaks caused by individual pieces of equipment, or allied pieces,
that must operate together. It may be preferable for the equipment use to be
shifted to a reduced-demand charge period. If the demand profile is
reasonably level, it may indicate that reduction of demand charges can only be
obtained through planned reduction in total consumption.
1.3 Specific Load Profiles. The next step in a demand survey is to record
electrical power consumption by substation, building, and department. This
enables the facility engineer to associate some of the causes of the
undesirable conditions with more specific load profiles. Some information
obtained from recording instruments at the building level will provide answers
to the following questions.
(a) Did the building equipment start on time in the morning and after
lunch?
(b) What is the load at noon and night?
(c) How long did it take for the building and each department to reach
full power load after startup?
(d) To what extent was quitting time anticipated at noon and in the
evening? Were machines left running idle?
(e) What is the idle load in the building?
(f) Does the building have a peak load that corresponds to the total
facility peak? What causes it? Could a change in scheduling reduce the power
demand?
(g) Is there evidence of pyramiding loads which cause excessive or
pulsating peaks?
(h) Does anything in the record offer explanations as to the waste of
power?
(i) What proportion of the demand charge and energy consumption should be
allocated to this building?
(j) What is the power factor?
9-41
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