Within any electronic system, the wires and cables are the points of entry
to the components most vulnerable to the electromagnetic environment.
While the processing of electronic information is carried out within the
chassis of electrical and electronic devices, the cabling that conveys data in
electrical from between systems transits through a hostile electromagnetic
environment. The interference signals from the environment, if mixed with the
intelligent signals being conveyed in the wires and cables, will cause
degradation of performance, confusion and sometimes physical damage to the
From a physical standpoint, cables are reliable components that can
withstand some abuse while continuing to function properly. Although physical
protection of cables is beyond the scope of this document, physical protection
may be combined with electromagnetic protection to maintain E3
integrity. E3 problems can cause physical damage when a strong
surge of energy results in heating or arcing within the wire or cable. Nearby
lightning strikes or a High Altitude Electromagnetic Pulse (HEMP) may result
in this type of damage.
The more common E3 cabling problems cause interference to the
signal being passed to sensitive equipment. This results in confusion to the
systems operation. This problem requires cabling protection with the same
degree of care and shielding effectiveness that the equipment chassis has.
The role of the manufacturing engineer, sometimes referred to as the
liaison or production engineer, is as the bridge between the designers and
those who are required to produce the finished product.
Theoretical designs must be producible in a competitive
Within any discipline, there are usually two levels of engineering
1. First there are basic principles and guidelines which are considered
"Best Practices." Both basic principles and Best Practices should be used
whenever possible for design and manufacturing of all systems. Usually
developed by manufacturing engineers, Best Practices become the standard
methods of manufacture by each discipline, or "craft." Often these practices
are not written down but are traditionally passed from journeyman to
apprentice. Some aspects for controlling electromagnetic environmental effects
fall into this category; e.g., methods of terminating shields, methods of
categorizing wires, and determining what particular types of cables and wires
are best used in each unique situation.
2. The second level of engineering principles deals with details specific
to a particular application based upon needs peculiar to that application.
Sometimes, design engineers may not be aware of the standard manufacturing
processes used to implement the particular design being developed, or they may
have evaluated them and found them inadequate for the particular
It is absolutely mandatory that the design engineer and manufacturing
engineer mutually Communicate their individual and specific requirements at
the outset of and throughout a project. This will assure that basic
E3 controls are maintained and that they are maintained in a way so
the equipment is producible at the most competitive price. It doesn't matter
to the client that an inadequate operational parameter discovered in
acceptance testing is attributable to a production flaw caused by
misinterpretation of a design guideline. It still will have to be fixed,
usually at additional expense to the manufacturer. The requirement for
continued communication between design and production engineers throughout a
procurement was the basic principle under which the BMP program was founded.
This section will provide a basic understanding of E3 principles
for cable hardening. This, in turn, should assist in arriving at optimum
methods of reducing coupling from the environment to the cabling and
throughout the airframe, between cables. Later sections of this document will
provide examples of standard "Best Practices" as well as some
application-specific examples that describe proven, successful procedures for
accomplishing EMI control within specific weapons systems.