MIL-H-80055B
3.5.1 Motor starter. Unless otherwise specified (see 3.7.2 and 6.2.1),
the motor starters shall be of the full voltage, across the line magnetic
type with overload protection, reset button, and a start and stop push
button control. Enclosure shall be of general purpose NEMA Type I. The
starters shall have a rating suitable for use with the MG set. On some
sizes, as an optional feature, the MG start-stop push button station may
be included as part of control station (see 3.7.2).
* 3.5.2 MG set, Unless otherwise specified (see 6.2.1), the MG set
may be either a vertical or horizontal type and shall be totally enclosed
and water cooled with motor and generator rotor on the same shaft. The
motors shall be a three phase, 60 Hz, squirrel cage induction type; and
the generators shall be a single phase, 3 KHz or 10 KHz as specified. The
motor Insulation shall be NEMA Class B, F, or H, and the generator insula-
tion shall be NEMA Class H. Bearings shall be grease or oil type, ball or
roller construction, and selected in accordance with bearing manufacturer's
recommendations covering application, speed, loading, and minimum life
expectancy of 30,000 hours. To minimize the danger of the generator rotor
rubbing the generator stator, design of the MG set shall include provisions
for the air gap clearance between rotor and stator to increase as operating
temperatures increase, and for an air gap clearance of .010 to .035 inch at
full load operating temperatures. Design of the MG set shall include ease
of maintenance of all components as well as features to minimize damage to
rotor or the stator due to bearing failure. The MG shall be vibration iso-
lated from its base or from the floor. Lifting eyes shall be furnished and
installed for transporting the MG set or for disassembly of same. The entire
shaft assembly including generator rotor, motor rotor, and integral fan shall
be dynamically balanced.
3.5.3 Control station. Unless otherwise specified (see 6.2.1), the
control station shall be complete with a steel enclosure, the thickness
of which shall not be less than 14 gage steel. The enclosure shall be
NEMA Type 12 and shall include the following generator controls and
monitoring instruments: ammeter, voltmeter, watt meter, and power factor
(KVAR) meter calibrated in percentages; and a generator field excitation
supply, including rectifier and field relay. Heat "on-off" control with
indicating lights shall be included. Output control through generator
field shall be provided by continuously variable autotransformer. A
control transformer to convert line voltage for control and field supply;
indicating lights to indicate control power, station ready, cooling water
on, field on, and overload shall be included in the control station. All
meters and controls shall be centrally located on the front panel of the
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