Delete frame size selection if not needed for the
project.
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Hoist motors shall be provided with insulation which has a [Class F] [Class
H] rating based on an [105] [125] degree C motor temperature rise above 40
degrees C ambient, with frame size selection based on continuous ratings.
2.4.4.6
Bridge and Trolley Motor Insulation and Time Rating
Bridge and trolley drive motors shall be provided with an insulation which
has a [Class F] [Class H] rating based on [105] [125] degrees C motor
temperature rise above 40 degree C ambient with frame size selection based
on continuous rating.
2.4.4.7
Micro-Motors
Micro-motors for [main hoist] [auxiliary hoist] [bridge] [and trolley]
drives shall be [direct current industrial type, shunt wound motors]
[industrial type, single-speed; single-winding; ac squirrel cage motor]
operation and shall conform to the requirements of NEMA MG 1. Micro-motor
shall be totally enclosed, fan cooled (TEFC), with Class F or H insulation.
Motor voltage rating shall comply with system supply voltage rating
specified.
2.4.5
Electric Brakes
2.4.5.1
Brakes
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NOTE: Delete this paragraph if hydraulic braking
system is not required.
If electric brakes are used, a drift point may be
provided so the brakes will release after the motor
is de-energized, thereby allowing the motion to
coast and reducing swing of the load. A drift point
can also allow the trolley to center itself over the
load before actually starting to lift.
For pendant control cranes and cab controlled cranes
where hydraulic braking is not desired, select
spring-applied electrically-released brakes. For
cab operated cranes, electric-hydraulic brakes
should be specified for bridge or trolley brakes
except in the case of constant speed/speed regulated
(at a particular controller setting) type controls.
Electric-hydraulic brakes should be limited to ac
magnetic or secondary saturable reactor and dc
magnetic controls for ac wound rotor motors and dc
series/compound wound motors respectively.
Electric-hydraulic brakes should be limited to
bridge brakes on bridge mounted cabs and trolley
brakes for trolley mounted cabs.
Electric-hydraulic brakes should not be specified
for the following:
SECTION 14630A
Page 33
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