TM 5-811-1 AFJMAN 32-1080
gives off sufficient vapor to form an ignitable
The voltage at which an arrester will stop conduct-
mixture with the air.
ing after discharge.
An outdoor transformer utilized as part of an
A residential development, or a mixture or resi-
underground distribution system, with enclosed
dential and small commercial establishments,
compartment(s) for high voltage and low-voltage
characterized by few pedestrians at night. This
cables entering from below, and mounted on a
definition includes areas with single family homes,
town houses, and/or small apartment buildings.
Secondary unit substation
Portland cement concrete road surface. Asphalt
A unit substation with secondary rated less than
road surface with a minimum of 15 percent of the
aggregates composed of artificial brightener.
Low-voltage system. Also see utilization voltage.
Asphalt road surface with an aggregate composed
Selective energy system
of a minimum 60 percent gravel. Mixed (diffuse
A selective energy system uses all the electric
energy that the installation system can generate
plus additional electric energy obtained from con-
ventional sources. Selective energy systems may
Asphalt road surface (regular and carpet seal) with
dark aggregates (e.g., trap rock, blast furnace
incorporate waste heat recovery systems.
slag); rough texture after some months of use
(typical highways). Slightly specular.
The root-mean-square phase-to-phase or phase-to-
neutral voltage at the point where the electrical
Asphalt road surface with very smooth texture.
system of the supplier and the user are connected.
Ungrounded systems, which do not carry a neutral
The maximum load consumed or produced by a
as such, and solidly grounded systems with neu-
unit or group of units in a stated period of time. It
trals that do not have at least four ground connec-
may be the maximum instantaneous load or the
tions per mile are example of "single-grounded
maximum average load over a designated period of
systems." See also ungrounded.
tion or substation.
any part of the circuit between the generator and
the distribution primary circuits.
An in-line pole.
Primary unit substation
A unit substation with secondary rated above 1000
Total energy system
V. For CEGS purposes, and articulated primary
A total energy system supplies energy require-
unit substation has both high voltage and low-
voltage sections mechanically coupled to the trans-
other uses from a single source making maximum
former, while a standard primary unit substation
use of available waster heat. Such a system is
has only the low-voltage section mechanically cou-
independent of other energy sources and is gener-
pled to the transformer.
ated and controlled by the user.
Medium-voltage. Also, see distribution voltage.
A common industry term for a wye-connected
system with its common point connected to earth
a t the source through a high-independence,
The maximum crest value of voltage that appears
current-limiting connection. Ungrounded systems
across an arrester's terminals under specified con-
are one form of single-grounded systems.
ditions of operation.