TM
5-811-1/AFJMAN
32-1080
distribution systems, the preferred distribution
will be used. The configuration proposed will be
voltage is the same as the existing distribution
commensurate with the degree of reliability re-
voltage. Use of 15 kV nominal-class systems is
quired by the mission or use of the facility. The
additional cost required to install loop or selective
preferable to 5 kV nominal-class systems unless
system studies indicate a clear advantage over the
systems will be justified. Individual components
15 kV system. Use of solidly grounded, multiple-
such as loop or selective switches at transformers
grounded systems is preferred over
will be considered where the project will need
single-grounded or ungrounded systems. For Air
increased reliability in the future. Special cases,
F o r c e , the preferred CONUS distribution is
involving large demands or high reliability re-
12,470Y/7,200 volt, three-phase, with delta pri-
quirements, may make the installation redundant
mary and wye secondary transformer connections.
sources of supply advisable. Hospital primary cir-
Voltages for facilities outside of the United States
cuit arrangements will be in accordance with the
are specified in AFM 86-3.
requirements of MIL-HDBK 1191, Medical and
Dental Treatment Facility Criteria, and other
1-7. Design Procedures.
Medical Facilities Design office criteria.
d. Short-circuit and coordination studies. Short-
Electrical power supply and distribution features
will be planned/delineated concurrently with plan-
circuit and protective devices coordination studies
will be in accordance with IEEE Std 242 and TM
ning stages of new installations and/or new facil-
5-811-14. Both linear and nonlinear loading will
ities on existing installations. The design process
be considered. Selection of protective devices and
starts with the DD Form 1391, Military Construc-
switchgear for a new electrical system will be
tion Project Data. This form provides information
based on a short-circuit protective device coordina-
necessary to categorize the power requirements of
tion analysis. For additions or modifications to an
the project. Two vital pieces of information are
existing distribution system, the analysis will in-
contained in the form: the scope of the project
clude all of the protective devices affected in the
which includes restoration, new facility, or new
existing system. All protective devices will be
i n s t a l l a t i o n (these all require different ap-
properly coordinated to provide selective tripping.
proaches); and the mission classification which
e. Expansion. Electrical power supply and distri-
includes mission essential, or mission support.
bution systems will be designed so that expansion
(Each is authorized a different degree of impor-
will be possible. Refer to IEEE Std 141 for addi-
tance in the hierarchy of power supply contigura-
tional and more detailed information regarding
tions and equipment.) The next part of the design
the expansion of electrical systems.
process involves estimating the power load re-
quirements; defining the measures to be employed
1-8. Evaluation and Selection of Energy Sys-
to meet the criticality requirements; and defining
tems.
the project power source requirements. At this
a. Selection of electrical energy sources for new
point a majority of the design bases can be
installations. The most economical electrical en-
formulated from the previous assessments and
ergy source will be selected based on criteria and
results, and final design features and configura-
tions can be developed.
guidelines contained in agency criteria.
(1) Feasibility study. Where necessary to de-
a. New installations. Electrical power supply
termine the most economical supply system, a
and distribution systems for new installations will
life-cycle-cost analysis will be performed in accord-
conform to prevailing utility company practices for
ance with methods discussed in 10 CFR 436,
that geographical area insofar as they do not
FEDERAL ENERGY MANAGEMENT AND
conflict with criteria, standards, and policy con-
tained within this manual.
PLANNING PROGRAMS. Choices include supply
b. Existing installations. Design for electrical
from a private, government owned generator
plant, co-generation, solar energy, or combination
power supply and distribution systems for new
facilities on existing installations will be coordi-
of options.
(2) Potential energy sources. In preparing fea-
nated with the Facility Engineer or the Base Civil
sibility studies, the potential energy sources com-
Engineer to assure compatibility with the electric
pared will include coal, oil, and purchased electric-
utility master plan. Designs will be compatible
with existing construction insofar as it does not
ity. Where applicable, refuse-derived, geothermal,
or biomass-derived fuel will be considered. Factors
conflict with criteria, standards, codes, and policy
contained within this manual.
affecting the choice of energy source will include
c. System configurations. Only radial, loop, or
availability, reliability, land right-of-way require-
selective configurations as illustrated in figure l-l
ments, station or plant site needs, first costs for
1-2
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