be mechanically and electrically interlocked.
2.4.6.1
Control Panels
**************************************************************************
NOTE: Control panel heaters are desirable for
outdoor cranes, unheated warehouse service cranes or
any other condensing high-humidity application.
Alternating current or dc static crane control for
outdoor cranes need thermostatically-controlled
panel heaters for outdoor panels or any other
application which is colder than 0 degrees C.
Alternating current or dc static crane control may
need both thermostatic control and mainline
contactor control.
**************************************************************************
Control panels shall be fabricated of solid sheet steel designed and
constructed to conform to requirements of NEMA ICS 6 Type [_____].
[Thermostatically-controlled heaters to keep control enclosure temperatures
at or above 0 degrees C shall be provided in each static crane control
panel.] [Control panel heaters shall be energized when mainline contactor
is de-energized, and shall be de-energized when mainline contactor is
energized to prevent anti-condensation.] Control panel doors shall be
hinged, equipped with gaskets and fitted with key-lock handle design,
complete with a single key to open all locks.
2.4.6.2
Main and Auxiliary Hoist Control
**************************************************************************
NOTE: Select a hoist control from the following
paragraphs a through i and coordinate with paragraph
Motors.
**************************************************************************
a.
Hoist motor control system shall provide one speed in each
direction with an electrically-operated, full-magnetic,
across-the-line reversing type starter. Speed contactors shall be
used to prevent the operation of high speeds and low speeds.
b.
Hoist motor control system shall provide two speeds in each
direction with of an electrically-operated, full-magnetic,
across-the-line reversing type starter. Electrical and mechanical
interlocks shall be used to prevent the operation of high speeds
and low speeds.
c.
Hoist motor control shall provide five-speed dc magnetic control
of ac wound rotor motor with eddy-current braking. Eddy-current
brake shall provide an adjustable varying artificial loading of
wound rotor hoist motor on at least two hoisting points and four
lowering points. Operation of hoist shall be prevented upon loss
of eddy-current brake excitation. Eddy-current brake shall be
excited with reduced voltage when hoist control is in the OFF
position. Positive-drive down is required on all lowering points.
On first speed-point hoisting, hook shall not lower with 100
percent of rated load, and the no-load hook speed shall not exceed
30 percent of rated speed. On first speed-point lowering, the
full-load hook speed shall not exceed 15 percent of synchronous
motor speed. A self-excited alternator shall be mounted on the
SECTION 14630A
Page 35
Previous Page
