motor to stop prior to reversing direction. If
excessive load swing cannot be tolerated during the
start of the bridge or trolley, include sentence on
reduced voltage starting.
a. Select drip-proof enclosure for indoor usage,
except in a hazardous atmosphere.
b. Select totally enclosed nonventilated enclosure
for outdoor use and indoor use in a hazardous
atmosphere.
c. Select totally enclosed fan cooled enclosure for
motors operating at rated speed for long periods.
d. Select forced ventilated enclosure for Class E
service.
**************************************************************************
Motor enclosures shall be [totally enclosed, non-ventilated (TENV)]
[totally enclosed, fan cooled (TEFC)] [totally enclosed, air-over frame
(TEAO)] [drip-proof] [drip-proof forced ventilation].
2.4.4.5
Hoist Motor Insulation and Time Rating
**************************************************************************
NOTE: For hoist motors, select Class F insulation
based on a rated temperature rise of 105 degrees C
by resistance above a 40 degree C ambient for CMAA
70 Class A, B, C cranes and CMAA 74 cranes with ac
or dc magnetic control and a mechanical load brake.
CMAA 70 cranes include top running bridge and gantry
type multiple girder electric overhead traveling
cranes. CMAA 74 cranes include top running and
under running single girder electric traveling
cranes utilizing an under running trolley hoist.
For hoist motors, select Class F or H insulation
based on a rated temperature rise of 105 (Class
F)/125 (Class H) degrees C by resistance above a 40
degree C ambient for CMAA 70 Class A, B, C cranes
and CMAA 74 cranes with ac or dc magnetic control
and electrical control braking.
For bridge and trolley motors, select Class F
insulation for MHI CMAA 70 Class A, B, C cranes and
CMAA 74 cranes with ac or dc magnetic control.
For all motors, select Class F or H insulation with
a rated temperature rise of 105 (Class F)/125 (Class
H) degrees C by resistance above a 40 degree C
ambient for CMAA 70 Class A, B, C and CMAA 74 cranes
with ac or dc static controls.
For all motors, select Class F or H insulation based
on a rated temperature rise of 105 (Class F)/125
(Class H) degrees C by resistance above a 40 degree
C ambient for CMAA 70 Class D and E cranes.
SECTION 14630A
Page 32
Previous Page
