MIL-DTL-3124E(SH)
3.3.3 Parallel operation. Single-phase generators shall not be required to operate in parallel. Three-phase
generators shall operate in parallel with real kilowatt and reactive kilovar load division in accordance with
MIL-G-21410 and MIL-R-2729.
3.3.4 Enclosures. The requirements for enclosures shall be in accordance with MIL-E-2036. Electrical parts
shall be enclosed to provide personnel protection against physical contact with electrically energized or moving
parts. The enclosures shall be one of the following, as specified (see 6.2):
a.
Open.
b.
Dripproof.
c.
Dripproof-protected.
d.
Totally enclosed.
e.
Totally enclosed (fan-cooled).
f.
Totally enclosed (water-air-cooled).
g.
Spraytight.
3.3.5 Ventilation. The ventilation system air inlets shall prevent hot air, developed by the prime mover, from
circulating through the generator. Water-air-cooled generators shall be as specified in 3.3.26.
3.3.6.1 Joints. Adjoining portions of machinery shall be given corresponding marks, where required, to ensure
correct assembly. Forcing bolts shall be provided for breaking babbitted, fitted, and stepped joints, and are not
required for inside bearing caps. "Where required" means anywhere two parts may be incorrectly assembled.
3.3.6.2 Dowels. Generators, other than flange-mounted, shall be doweled against movement by the use of
fitted holding-down bolts. Dowels shall meet the shock conditions specified in 3.4.17. Dowels, ½ inch or more in
diameter (diameters refer to the small end of the dowel), shall be provided with threads and nut for withdrawal.
Taper dowels shall not be larger than 3/8 inch in diameter. Dowels shall be located so as to be removable using a
boxed or open ended wrench without disassembly of adjacent parts.
3.3.7 Armatures (see 6.5.3). Laminations shall be insulated with a C-5 coating in accordance with
ASTM A976. Spacers used for ventilation shall be riveted or welded to the laminations to prevent their coming
loose due to vibration in service. In the assembly of the cores, burrs or projecting laminations in the slot portion o f
the core shall be removed to prevent injury to the coils.
3.3.8 Bearings. Bearings shall be sleeve, ball, or roller type as specified (see 6.2). Other bearing types may be
proposed, but are subject to NAVSEA review and approval. The lubrication system shall prevent oil, oil-laden
vapor, or grease from leaking or migrating from the oil seal bearing housing or split lines under the inclined
operation conditions specified in 3.4.19, and maintain positive seal cavity pressure during operation. Bearings shall
be insulated where required (see 3.3.24.5).
3.3.8.1 Sleeve bearings. Sleeve bearings mounted in a pedestal shall be self-aligning. Bracket-mounted sleeve
bearings need not be self-aligning. Sleeve bearings for generators with a frame size larger than that corresponding
to 100 kilowatts at 1200 revolutions per minute (r/min) shall be split to permit removal and replacement without
taking the rotor out of the frame, removing the coupling from the driving end, or removing the bearing bracket from
the generator. Sleeve bearings for generators with frame sizes corresponding to 100 kilowatts at 1200 r/min and
smaller need not be of the split type under the following conditions:
a.
The bearing shell and oil seal shall be removable and replaceable without removing the bracket.
b.
The bearing shell shall be removable without removing any overhung exciters, armatures, or coupling.
3.3.8.1.1 Lubrication. Sleeve bearings shall be lubricated by the prime mover forced feed lubrication system
(see 3.4.11). Lubricating oil shall be in accordance with MIL-PRF-17331, Symbol 2190 TEP, or MIL-DTL-32353,
Symbol 2190S, as specified by NAVSEA.
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