A new analysis of the influence from external EMI sources onmultiple underground cables
Han Fang; Gao Yougang
Electromagnetic Compatibility, 1989. IEEE 1989 National Symposium on
Volume , Issue , 23-25 May 1989 Page(s):303 - 308
Digital Object Identifier 10.1109/NSEMC.1989.37197
Summary:A theoretical analysis is presented for currents along, and
voltages between, sheath and core conductors induced by external sources
of electromagnetic interference (EMI) in multiple-conductor underground
cables. The mutual coupling among the cables of either infinite length
or finite length is taken into account. The terminal effects from the
boundary conditions of finitely long cables and the effect of grounding
on the coupling are analyzed. The analysis is based on the model
presented previously by the author (see J. Electrot., No. 1, 1989).
Using this model, the general solutions to currents and potentials along
the cable sheaths are first derived, and then the current in each core
conductor, and the voltage between the sheath and core conductor are
determined. For finitely long cables, the above model is valid if
ordinary boundary conditions, i.e. the arbitrary terminal impedance
between the sheath and the earth, are taken into account. These
so-called terminal effects can either strengthen or restrain the
influence from external EMI sources depending on their phase
superposition. It is shown that the terminal effect may become less
important when the cable lengths get longer. Thus, the results for
infinitely long cables can be achieved when the cables are sufficiently
long. Examples are analyzed for some special EMI sources such as
conductive and current energizations. Satisfactory solutions to these
influences are derived
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