S9407-AB-HBK-010 Datasheet, PDF (133/276 Pages) Glenair, Inc. – HANDBOOK OF SHIPBOARD ELECTROMAGNETIC SHIELDING PRACTICES

S9407-AB-HBK-010, Rev. 2
6.9 SPACING AND SHIELDING REQUIREMENTS FOR SUSCEPTIBLE CABLES TO OTHER
INTERFERENCE SOURCES
Special consideration must be given to susceptible cables that are to be routed near
interference sources such as power distribution panels, fluorescent lights, motor generator sets,
motors, transformers, controllers, and equipment cabinets.
6.9.1 Susceptor Categories S1 Through S4
Figure 6-8 provides the spacing and shielding requirements for susceptible cables to
interference sources for the categories and group numbers listed. It is provided as guidance to afford
protection to susceptible cables for the general case. The group numbers (of categories S1, S2, and
S4) not listed in figure 6-8 are permitted zero inches of spacing without shielding.
6.9.2 Susceptor Categories R4 Through R8
Three inches of spacing are required between susceptible cables in these categories and
interference sources listed in paragraph 6.9. When the 3-inch spacing cannot be achieved, shielding
with flexible or rigid metal conduit is required. Cables in this category are permitted zero inches of
spacing when 20 dB of shielding is provided.
6.10 GUIDELINES FOR EMC CABLEWAY DESIGN
The following general guidelines may be used in cableway design to implement the
requirements of this section. Although there are many different cable categories and groups identified
in Section 6, in practice only two separate cableways may be necessary to provide the required
spacing to prevent radiator cables and equipment from inducing EMI into susceptor system cables.
6.10.1 Guidelines for Susceptor Cableway Design
The most sensitive susceptor cables will usually require a cableway separated from radiator
cableways, external shielding conduit or both to prevent EMI. The following information is obtained
from the cable spacing charts, figures 6-6 and 6-8.
a. Susceptor cables in categories S1, S2, S3 and S4 may be routed together with no
spacing required between them.
b. If there are radiator cables (see figure 6-6) or interference sources (see figure 6-8)
within 64 inches from the susceptor cable-way, an analysis shall be conducted in
accordance with paragraph 6.8 to determine the spacing required between the radiator
cable and equipment and susceptor cables for the specific situation involved. Route the
susceptor cableway to obtain the necessary spacing. Those susceptor cables with
requirements for zero spacing from radiator cables may be routed in a radiator
cableway.
c. If the required spacing of figures 6-6 and 6-8 is not practical, recalculate the spacing
requirements with the susceptor cables installed in flexible conduit.
d. If the required spacing of figures 6-6 and 6-8 is still not practical, recalculate the spacing
requirements with the susceptor cable installed in flexible conduit inside an additional
short piece of rigid or flexible conduit in a partial shielding application, see paragraph
6.7.1.
6-20