Browse Prior Art Database

EMI/ESD Resistant Bulkhead Entrance for Shielded Cable

IP.com Disclosure Number: IPCOM000121265D
Original Publication Date: 1991-Aug-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Dee, J: AUTHOR [+3]

Abstract

When cabling between boxes in a computer environment, noise problems typically result from electromagnetic interference (EMI) and electrostatic discharges (ESD). The resultant noise can cause the loss of data, and in some cases may damage integrated circuitry. Cables designed to work in such environments are usually made by shielding the signal conductors. Applications using long cables (>20 feet) typically drive the signals differentially so that coupled noise between signals can be eliminated. Again these differential signal pair conductors are surrounded by a shield to eliminate EMI and ESD problems.

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EMI/ESD Resistant Bulkhead Entrance for Shielded Cable

      When cabling between boxes in a computer environment,
noise problems typically result from electromagnetic interference
(EMI) and electrostatic discharges (ESD).  The resultant noise can
cause the loss of data, and in some cases may damage integrated
circuitry.  Cables designed to work in such environments are usually
made by shielding the signal conductors.  Applications using long
cables (>20 feet) typically drive the signals differentially so that
coupled noise between signals can be eliminated.  Again these
differential signal pair conductors are surrounded by a shield to
eliminate EMI and ESD problems.

      In order for the shield to protect the underlying signal
conductors, a very low impedance connection between this shield and
the box frame must be maintained.  To provide a low impedance path at
high frequencies, the DC resistance between the shield and the frame
should be limited to a maximum of 10 milli-ohms.

      The connection between the cable and the box should also
provide adequate strain relief since an interbox cable would be in a
raised floor environment.

      This bulkhead entrance design (see the figure) provides for a
low impedance path from the shield to the frame, strain relieves the
cable, and allows the signal conductors to pass through the frame
without the use of a connection point.

      The cable passes through the connector body where a strain
relief is...