MIL-HDBK-1003/11
Section 3:
INFORMATION REQUIRED FOR DESIGN
3.1 Introduction. This section defines the data that must be developed to
establish engineering design bases and to evaluate between various design
and ownership alternatives.
3.2 Electrical Loads. Electric loads should be determined carefully to
size electric generating plant components properly. The duration and
variation of electric loads should be determined to provide inputs to
required life-cycle cost analyses and for various clauses when tailoring
NAVFAC guide specifications, (refer to Section 1) for procurement purposes.
3.2.1 Electric Load Determination. To determine the electric load that the
plant must satisfy, utilize the load estimating data described in NAVFAC
DM-4.01, Electrical Engineering, Preliminary Design Considerations. For
retrofit projects, the local utility may be able to supply load duration
curves from actual metering records.
3.2.2 Typical Electrical Load Curves.
Figure 1 is an example of a typical
electrical load curve.
3.2.2.1 Growth Curve. In Figure 1(a), note the normal trend of growth in
electric demands and the additional loads (steps) when new buildings or
processes are added. Development of this data and preparation of the growth
curve is useful in timing additions to power plant generating capacity.
3.2.2.2 Average 24-Hour Load Curves. The average of daily electrical
demands in Figure 1(b), showing 24-hour variation in seasonal demands, is
very important. Such curves are useful in determining load factors, the
duration of certain demands, and in dividing the total electric load among
plant units. This information is a necessary factor in life-cycle cost
analyses to be conducted when selecting among alternative designs and
equipment configurations.
3.2.2.3 Annual Load Durations Curves. Plot the duration in hours, of each
load during a year for both present and future load conditions. The type of
curve shown in Figure 1(c) is useful in determining load factors and in
sizing electric generating plant equipment. Information from this curve is
also used in required life-cycle cost analyses. Durations of plant electric
loads at full load, three-quarters load, and at one-half load is a required
input for tailoring NAVFAC guide specifications.
3.3 Duty and Capacity Requirements for Electric Generating Plants. Sources
and duty types of electric generating plants are defined in Section 2.
Table 2 summarizes capacity requirements as related to each duty type.
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