MIL-PRF-19004B
3.16
Electrical equipment for fans.
3.16.1 Motors. Motors shall be as specified in 3.16.1 through 3.16.8. Motors
shall conform to IEEE STD 45, NEMA MG 1 and MG 13 as applicable and as
augmented herein.
3.16.1.1
General requirements for motors.
Service:
Fan type CC - grade A shock qualified
Fan type X-CC - commercial motor
HP:
Table II
Design:
Squirrel cage induction
Duty:
Continuous
Voltage and phase: 440-V, 60 Hz, 3-phase
Insulation:
Class F or better with Class B temperature rise.
(IEEE STD 429)
Bearing:
See 3.16.3, 3.16.5
Speed:
Table II (see 3.16.4)
Enclosure:
Spraytight, or explosion-proof as specified in
6.2
3.16.2 Conduit box. A conduit box shall be provided on the motor.
It shall
meet tightness requirements of motor enclosure.
3.16.3 Bearings. Motors shall be equipped with sealed grease-filled
bearings. Bearings shall be in accordance with ANSI/ AFBMA precision
classification of ABEC-5 in accordance with ANSI/AFBMA STDS 4, 9, 10, 13, and
20. Means shall be provided to ensure that grease is always available to the
bearing and to prevent the leakage of oil or grease along the shaft. Special
bearings for quiet operations when specified (see 6.2) shall be in accordance
with ANSI/AFBMA 4, 9, 10, 13, and 20 and MIL-B-17931.
3.16.4
Speed.
Speed and horsepower shall be limited to Table II.
TABLE
II.
Speed and horsepower of 440 V,3 phase, 60 Hz motors, type CC and
X-CC fans.
Fan
No. of
Maximum
Maximum
size
windings
hp
Speed
rpm
¼
1
¼
Single
1800
½
1
¾
Single
1800
1
1
1
Single
1800
1½
1
1
Single
1800
2
1
1½
Single
1800
3
2
3
Full and
2/3
1800/1200
4
2
4
Full and
2/3
1800/1200
5
2
5
Full and
2/3
1800/1200
6
2
5
Full and
3/4
1200/900
8
2
7½
Full and
3/4
1200/900
10
2
10
Full and
3/4
1200/900
3.16.5 Bearing temperature rise. Bearing temperature rise shall not exceed
63 °F in 149 °F ambient as measured on bearing outer ring. For quiet
bearings, temperature rise shall not exceed 45 °F in 149 °F ambient as
measured on bearing outer ring.
3.16.6 Drains. All spraytight motors shall be provided with not less than
four condensate drain holes fitted with plugs. The holes shall be positioned
around the motor end bell(s).
8
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