series device data sheets will contain the phrase
"tested using extended range buffer networks" and
will satisfy the stated performance under full load
at frequencies below 100 kHz. The "X" series
filters will also be tested in accordance with
MIL-STD-220. The "X" series filters can also be
differentiated from "W" devices by the fact that
they are usually two to three times greater in
weight.
Fire alarm, signal, energy monitoring and control
system, telephone, and control lines require filters
that pass a specific frequency, voltage, and number
of conductors. Fire alarm circuits with ground
fault indicators will show a ground fault when
connected through a filter and should be avoided. A
fiber optic connection through the shield is
recommended. Conductors penetrating the shield
perimeter shall be kept to a minimum. Systems
penetrating the shield will have special
requirements in their specifications for
compatibility between system signal and control
circuits and the EM filters.
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2.6.2.1
Filter Construction
Individual filters shall be heavy-duty type sealed in a steel case. After
the filter is filled with an impregnating or encapsulating compound, the
seams shall be welded. When a solid potting compound is used to fill the
filter, the filters may be mechanically secured and sealed with solder.
Hermetically sealed impregnated capacitors shall be used, or the complete
filter assembly shall be vacuum impregnated. Individual filter cases shall
be fabricated of not less than 2 mm 14 gauge thick steel and finished with
a corrosion-resistant plating,or one coat of corrosion-resistant primer and
two coats of finish enamel. The filter shall be filled with an
impregnating or potting compound that is chemically inactive with respect
to the filter unit and case. The compound, either in the state of original
application or as a result of having aged, shall have no adverse effect on
the performance of the filter. The same material shall be used for
impregnating as is used for filling. Filter terminals shall be copper that
can withstand the pull requirements specified and measured in accordance
with paragraph ELECTROMAGNETIC FILTERS.
2.6.2.2
Ratings
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NOTE: Indicate maximum current, voltage, and pass
band frequency ratings on the drawings. If no
drawings are furnished with the specifications,
specify the ratings here.
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[Filters shall be provided in the current, voltage, and frequency ratings
indicated on the drawings.] [Filter current shall be [_____].] [Filter
voltage shall be [[120] [208] [277] [480] volts, 60 Hz] [[230] [250] [400]
volts, 50 Hz].] [The pass band frequencies [_____] Hz to [_____] Hz shall
be suitable for use with the [50] [60] [_____] [and] [400] [_____] Hz power
source and signal line filters as indicated.]
SECTION 13095A
Page 30
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