Quantcast Transients and Harmonics Protection

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MIL-HDBK-1038
electrification systems; an equipment grounding conductor is required to be
included as one of the conductors in rigid conductor systems.
A copper ring/collector assembly is required to be provided on newer
cranes to ground each hoist drum.  The ring is required to be electrically bonded
to the drum.  The collector is required to be stationary and connected to the
equipment grounding conductor by means of a No. 8 AWG copper wire.
For lightning protection on portal, floating, and container cranes,
bonding conductors are required to be provided across all gudgeons and the boom
and strut hinge pins; the minimum size of these conductors is to be 2/0 AWG.
Also, the upperworks of a portal or floating crane is required to be electrically
bonded to the portal base utilizing 2/0 AWG conductors and a collector ring having
a minimum cross-sectional area of 70 square millimeters.
On outdoor bridge cranes, the runway and bridge-to-trolley
electrification system conductors serving as equipment grounding conductors are
required to have a minimum cross-sectional area of 70 square millimeters.
5.5.5.21 Transients and Harmonics Protection.  Transients protection for each
adjustable frequency or flux vector controller is required to be provided,
consisting of metal oxide varistors (MOVs) connected line-to-ground close to the
line terminals of the controller.  A monitoring circuit is required to be
connected to indicate a blown MOV.  The circuit is required to disable the control
circuit of the affected drive.
With motors of 50 horsepower or greater, minimum harmonics protection for
a flux vector controller is required to be provided, consisting of an isolation
transformer and a detuned harmonic filter.  The filter is required to consist of a
capacitor bank connected in series with a reactor; they are required to be tuned
to have a low impedance at a series resonance frequency between 270 and 290 Hertz.
The filter is required to be connected across-the-line between the transformer and
the controller.
Minimum harmonics protection for adjustable frequency controllers, and
for flux vector controllers for motors smaller than 50 horsepower, is required to
be provided, consisting of a reactor connected in series with the input of the
controller.
5.5.5.22 Standing Wave Protection.  For motor branch circuit conductor lengths
exceeding 100 feet, reactors are required to be connected in series with the
output of flux vector controllers and adjustable frequency controllers.
5.5.5.23 Lighting Fixtures.  In mercury exclusion areas, fluorescent and high
intensity discharge lamps (which contain elemental mercury) must be installed
within sealed lenses or refractors which serve as a second means of containment
for the mercury.  Otherwise, incandescent lamps are required to be used to
illuminate crane passageways and space while metal halide or tungsten halogen
(quartz) lamps are required to be used in floodlights and spotlights.
On outdoor cranes, exterior footwalks are required to be illuminated to 5
footcandles.  In the machinery houses on portal, floating, and container cranes,
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