Operation of the unit requires a three-phase,
A portion of the generated ac power is rectified
60-hertz, 220- or 440-volt ac external power
to supply 28-volt dc at 750 amperes continuously.
source. It is used both aboard ship and ashore.
The unit is self-contained and requires no
The unit is not self-propelled and must be
external electrical or mechanical sources of power.
towed or manually moved. The four-wheel trailer
It may be towed at speeds up to 20 mph. The
is equipped with tie-down rings, pneumatic tires,
efficiency of the NC-10C is not affected on
and a tow bar in front for towing or manual steer-
inclines up to 15 degrees maximum in any direc-
ing. A mechanically actuated hand brake, located
tion from horizontal. Climatic conditions of
on the front of the unit, is connected to
operation are from 18F to 120F ( 22C to
drum/shoe type of brakes on the rear wheels.
50C) and under relative humidity up to 100
Maximum towing speed is restricted to 5 mph.
percent. It will operate efficiently at altitudes from
The MMG-1A weighs 4,120 pounds. It is 7 feet
sea level to 8,000 feet.
10 inches long, 4 feet 2 inches wide, and 3 feet
The general hazards of high voltage, hot
6 inches high.
cables, noise, noxious gases, and exhaust heat are
Stowage compartments are located at the rear
all applicable to the NC-10C. There is also no
lockout circuit to prevent moving the unit with
of the unit for 30-foot ac and dc output cables.
The 30-foot input power cable is stowed in a
the cables still plugged into the aircraft.
compartment at the left front side of the unit.
MOBILE MOTOR-GENERATOR SETS
Control panels and a utility power connector
(MMGs)
panel are located under fold-open panels on the
right front side of the unit. A portable floodlight,
Mobile motor-generator sets perform the same
which can be attached to a mounting bracket atop
function as the mobile electric power plants, but
the unit, is stored in a door compartment at the
they are not self-contained and require an external
front of the unit.
source of electrical power for operation. The
MMG-1A and MMG-2 are primarily used in
MMG-2 Motor Generator Set
hangars on shore stations, or on the hangar decks
The MMG-2 is physically quite small and
of aircraft carriers where the running of an
compact. See figure 3-7. It is a trailer-mounted,
internal combustion engine would be objection-
electric motor-driven generator set used to
able and where external power (220-440/60 Hz)
provide 120/208-volt, 400-Hz ac power, and
is readily available.
28-volt dc power for use in ground maintenance,
MMG-1A Motor Generator Set
calibration, and support for all fighter/interceptor
The MMG-1A, shown in figure 3-6, is a small,
types of aircraft equipment.
compact, trailer-mounted, electric motor-driven
MOBILE AIR-CONDITIONERS
generator set used to provide 115/200-volt, three-
Mobile air-conditioners are designed to
phase, 400-hertz ac, and 28-volt dc power for
cool, ventilate, dehumidify, and filter the air used
ground maintenance, calibration, and support for
in aircraft cabins and compartments. Although
various types of aircraft systems and equipment.
mobile air-conditioners are usually associated
Figure 3-7.-MMG-2.
Figure 3-6.-MMG-1A.
3-6