IEEE Std 2746-2020 pdf download – IEEE Guide for Evaluatng AC Interference on Linear Facilites Co-Located Near Transmission Lines.
4.1.3 Conductive Conductive coupling in ac electrical systems is the method of energy transfer of which most engineers are familiar. When time-varying electric fields are present in energized transmission lines, a voltage gradient and electrical current are established within the conductors. If inadvertent physical contact is made between one of the energized conductors and another conductive object, (commonly referred to as an electrical fault), the conductive coupling can result in significant energy transfer and cause severe damage. If the voltage gradient is high enough to exceed the breakdown voltage of the surrounding material, an ionized current conducting channel can be formed, which is referred to as an arc fault. In the context of ac interference on co-located facilities, coupling involving a grounded object (line-to-ground fault) is the most prevalent concern, as the earth becomes part of the return path for the fault current and can energize other objects also in contact with the soil. Unbalanced faults, especially single-line-to-ground faults, which occur near the co-located linear facility or beyond the shared corridor, typically represent the greatest risks to personnel and equipment. Some common modes of triggering a ground fault include encroaching foliage, lightning-induced fashovers, animals, and equipment failures. Co-located linear facilities, equipment, and other objects susceptible to the effects of conductive coupling include shield wires and OPGW cables, above-grade metallic objects, metallic fencing, handrails, and other adjacent overhead lines. Below-grade metallic objects, such as pipelines and grounding systems, can be directly affected by the voltage gradients in the soil.
4.2 General considerations for ac interference analysis AC interference analysis is a complex combination of several effects, as addressed above. In all but the simplest cases, the use of software is necessary to completely analyze these interference effects, incorporating a large amount of site-specific data. The following subsections discuss the general considerations for ac interference analysis, specifically related to aspects regarding the transmission line and items common to most interference studies. Specifics related to pipelines and railroads are found in Clause 5 and Clause 6, respectively. An example of a simple ac interference project is described in Annex B, while Annex C provides example results from a complex ac interference project.