A filter shall be provided for each power, data, and signal line
penetrating the enclosure. These lines shall include, but are not limited
to, power lines, lines to dummy loads, alarm circuits, lighting circuits,
and signal lines such as telephone lines, antenna lines, HVAC control, and
fire alarm. Filters [and ESAs] shall be enclosed in metallic cases which
shall protect the filter elements from moisture and mechanical damage. All
external bonding or grounding surfaces shall be free from insulating
protective finishes. All exposed metallic surfaces shall be suitably
protected against corrosion by plating, lead-alloy coating, or other means.
The finish shall provide good electrical contact when used on a terminal
or as a conductor, shall have uniform texture and appearance, shall be
adherent, and shall be free from blisters, pinholes and other defects. The
filter [and ESA] assemblies shall also meet the requirements of UL 1283.
Insertion loss in the stop band between the load side of the filter and the
power supply side shall be not less than the EM shielding attenuation
specified. The filter used for 400 Hz shall be provided with power factor
correcting coil to limit the reactive current to 10 percent maximum of the
full load current rating. Each filter unit shall be capable of being
mounted individually and shall include one filter for each phase conductor
of the power line and the neutral conductor. The signal filters shall
include one filter for each conductor.
2.6.1
Enclosure
**************************************************************************
NOTE: The intent of this paragraph is to preserve
the integrity of the filter and to shield the input
and output circuits from each other. Usually, this
is accomplished by mounting the filters in an
EM-modified NEMA Type 1 enclosure with separate
compartments for the input and the output terminals.
If a weatherproof or hazardous area type enclosure
is needed, it must be specified.
**************************************************************************
Filter units shall be mounted in an EM modified NEMA Type [1] [_____]
enclosure in accordance with NEMA ICS 6 and meet the requirements of UL 1283.
Enclosures shall be made of corrosion resistant steel of 1.9837 mm 14 gauge
minimum thickness with welded seams and galvanized bulkhead cover plates.
The enclosure nonconductive surfaces shall be finished with a
corrosion-inhibiting primer and two coats of baked or finish enamel. The
input compartment shall house the individual line filters and the input
terminals of the filters and mounting for the surge arrestor. Live parts
shall be spaced in accordance with NFPA 70. Filter leads shall be copper.
Filter enclosures shall be shielding effectiveness tested in accordance
with IEEE Std 299 and Table I of this specification. [Test leads and
coaxial connectors through the enclosure shall be provided for HEMP
testing.] [The imbedded configuration shall be used for filter enclosures
as required by MIL-STD-188-125-1.]
2.6.1.1
Filter Unit Mounting
Each filter unit shall be mounted individually in an enclosure containing
one filter for each penetrating conductor. One end of the individual
filter case shall be attached to the rf barrier plate between the two
compartments to provide a rf tight seal between the rf barrier plate and
the filter case. The terminals of the filters shall project through
openings in the rf barrier plate into the inner terminal compartment. The
SECTION 13095A
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