TM
5-811-1/AFJMAN
32-1080
CHAPTER 1
GENERAL
1-1. Purpose.
functional flow diagrams, space requirements, se-
curity requirements, etc.) to determine the power
This manual provides Department of the Army
supply configurations required to achieve the nec-
and Air Force policy and guidance for design
essary degree of reliability, durability, maintain-
criteria and standards for electrical power supply
ability, efficiency, and economy.
and distribution systems.
a. Reliability. System reliability describes and
1-2. Scope.
quantifies the ability of a system to consistently
provide power to a facility. The designer will
The design criteria and standards contained within
request using agency to provide the allowable
are the minimums acceptable for Department of
frequency and duration of both forced and mainte-
the Army and Air Force installations for efficiency,
nance outages. The designer will evaluate the
economy, durability, maintainability, and reliabil-
supply source reliability data (outage records) and
ity of electrical power supply and distribution
determine the system configuration required to
systems. Where special conditions and problems
meet the required availability. For supply scenar-
are not covered in this manual, applicable industry
ios where the allowable outage frequency and
standards will be followed. Modifications or addi-
duration requirements cannot be met with a
tions to existing systems solely for the purpose of
single-source design, the designer will develop
meeting criteria in this manual will not be autho-
mathematical and supporting cost models for
rized. The criteria and standards herein are not
multiple-source or redundant-feed distribution sys-
intended to be retroactively mandatory. The word
tems to achieve the required availability, utilizing
"will" identifies guidance. The word "shall" identi-
IEEE Std 493 methods. An alternative comparison
fies policy and is used when writing legal, contrac-
assessment will be developed to evaluate the reli-
tual, requirements such as statements of work,
ability choices utilizing IEEE Std 493 methods.
specifications or any other documents that require
b. Durability. Electrical systems and electrical
compliance from the commercial/industrial sector.
equipment will be designed for the design life of
Clarifications of baseline design criteria, standards,
the facility: 25 years for permanent construction,
policy, and guidance should be obtained through
6 to 24 years for semi-permanent construction, and
normal Army and Air Force channels, from HQU-
5 years for temporary construction.
SACE CEMP-ET, Washington, DC 20314-1000 or
SQ AFCESA/ENE, 139 Barnes Drive, Suite 1,
tems will incorporate features which provide ac-
Tyndal AFB, FL 32403-5319.
cess space for maintenance in accordance with the
1-3. References.
NEC and NESC, and means to replace equipment
and field installed wiring without significant dem-
Appendix A contains a list of references used in
olition and reconstruction of parts of the facility.
this manual.
d. Economy. Agency criteria and AR 11-18 es-
1-4. Standards and Codes.
tablish the economic consideration requirements
which will be assessed for each facility. For Air
Applicable electrical industry codes, standards, or
Force, refer to AFR 173-15.
publications referenced will apply to equipment,
materials, and construction covered herein. The
1-6. Electrical Power Systems.
minimum requirements of the latest version of
NFPA-70, the National Electrical Code (NEC),
Electrical power systems for Army and Air Force
and ANSI C2, the National Electrical Safety Code
installations can be composed of subtransmission
(NESC), will be met and exceeded when more
lines to main substations; distribution lines to
stringent requirements are specified and/or dic-
distribution substations; utilization lines to distri-
tated.
bution transformers; and generators to provide
emergency, stand-by, and/or prime power for mis-
1-5. Power Supply Design Criteria.
sion essential/critical loads. Generally, for Army
The designer will review the project requirements
base-wide distribution changeouts, the preferred
documents (Project Development Brochure, DD
CONUS voltage is 13.2 kV or 13.8 kV three-phase,
Form 1391 (FY, Military Construction Project
three-wire, with delta primary and wye secondary
Data), project requirements outline, source data,
transformer connections. When extending existing
1-1
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