Interface Standards for Shipboard Systems
Section 300A
Electric Power, Alternating Current
Types of shipboard electric power to be supplied
from the electric power system are as follows:
Type I -Type I power is 440 or 115 volts (V), 60 hertz (Hz)
ungrounded and is the standard shipboard electric
power source. Type I power shall be used unless a
deviation is granted.
Type II - Type II power is 440 or 115 V, 400 Hz ungrounded and
has only limited application. Use of type II power
requires the submittal and approval of a deviation
request.
Type III - Type III power is 440 or 115 V, 400 Hz ungrounded having
tighter tolerances as compared to types I and II.
Type III power has restricted use and its use requires
submittal and approval of a deviation request.
Special power classification. Types of shipboard electric power
supplied only for avionic shops and aircraft servicing are as follows:
Type I - Type I power is 115/200 V, 60 Hz, 3 phase, 4 wire, Wye
grounded. This power is only provided for avionic shops.
Type III - Type III power is 115/200 V, 400 Hz, 3 phase, 4 wire
Wye grounded. This power is only provided for avionic
shops and for aircraft servicing.
Types of power are as follows:
(a) Type I, 60 Hz power: the ship service power distribution system
supplied by the ships generators is 440 V, 60 Hz, three-phase,
ungrounded. The ships lighting distribution system supplied
from the ship service power distribution system through transformers
is 115 V, 60 Hz, three-phase, ungrounded. The 115 V,
60 Hz, three-phase, ungrounded circuits are also available
through transformers to supply other user equipment, (for
example, electronic equipment). Single-phase power is available
from both the 440 V and the 115 V systems. The ship service
power and lighting distribution systems are designated as type
I. See 1.3.1 for special power type.
(b) Type II and III, 400 Hz power: The ship service power supplied
by 400 Hz motor generator sets or solid state converters is 440 V
three-phase, 400 Hz, ungrounded. The 400 Hz power is of two
kinds, designated as type II and III. Subject to approval of
a deviation request, the use of type II is preferred over type
111 but, if more precise characteristics are mandatory, type 111
power may be supplied. Table I specifies the characteristics
of types II and III power.
See Naval use Environment, or the Military Specifications page.
