S9407-AB-HBK-010 Datasheet, PDF (125/276 Pages) Glenair, Inc. – HANDBOOK OF SHIPBOARD ELECTROMAGNETIC SHIELDING PRACTICES

S9407-AB-HBK-010, Rev. 2
6.8 PROCEDURES FOR CALCULATING CABLE-TO-CABLE SPACING AND SHIELDING
The basic approach for achieving proper cable spacing and shielding is presented in the
following steps.
a. Determine the amount of cable-to-cable spacing (physical separation) required between
radiator cables and susceptor cables to eliminate coupling.
b. If adequate spacing between cables is not practical on shipboard, install the susceptor
cables in flexible shielding conduit. With this shielding, reduced spacing is required
between the conduit containing the susceptor cables and the radiator cable or
equipment. Note that shielding of susceptor cables verses the radiator cable is
preferred because:
• There are fewer susceptor cables.
• Once shielded, they are protected from relocations or
subsequent installations of nearby radiators.
• Susceptor cables may be run together in the same conduit, resulting in a potential
cost reduction.
• Installing the maximum shielding required on susceptor cables reduces the need to
shield both susceptor and radiator cables.
• Shielding radiator cables in flexible conduit may cause conduit saturation with
subsequent loss of shielding effectiveness.
c. Where the combination of cable-to-shielded "S" cable spacing is inadequate, keep the
"S" cable enclosed in flexible shielding conduit and enclose the "R" cable in flexible or
rigid shielding conduit. NOTE: Radiator cables having certain "R" designators require
shielding in rigid shielding conduit. (See paragraph 6.7.2.).
d. The following documents may provide assistance in determining the cable spacing and
shielding requirements. They may be obtained by requesting a copy from the EMC
Branch, Code 3431 of the Naval Underwater Systems Center, Division Newport,
Newport, RI 02841-1708, telephone [phone] or autovon (920)5540.
(1) NUSC Technical Memorandum 871161, Dated 2 September 1988, classified
CONFIDENTIAL, provides a listing of equipment design-performance sensitivity
required for the categorization of input signal cables for various government
furnished equipments.
(2) NUSC Technical Memorandum 811123 of 15 December 1981 provides a
computer program for the HP 85 computer to assist in calculations for cabling
and shielding requirements.
This approach is described in detail in the procedures listed below.
The following two procedures, when properly applied, give the spacing required for cables
without shielding and, if necessary, the shielding conduit required for adequate protection of
susceptible cables. Procedure 1 (paragraph 6.8.1) covers susceptor categories S1, S2, and S4.
Procedure 2 (paragraph 6.8.2) covers susceptor categories S3 and R4 through R8.
CHANGE 1 of Revision 2
6-12