IEEE 1793:2012 pdf free download – IEEE Guide for Planning and Designing Transition Facilities between Overhead and Underground Transmission Lines
3.1.2 Community considerations
There are a number of community issues to be considered in siting a transition facility. These include thefollowing:
– Noise: Noise sources at transition facilities can include shunt reactors，pressurizing and coolingequipment (for pipe-type cables),switching noisc， and corona and gap discharge related noise.Standard noise evaluating techniques for substations can be used to evaluate reactor andpressurizing plant/cooling plant noise.Switching noise tends to be very infrequent, and is generallynot a significant siting issue. Corona and gap discharges can gencratc audible noise andelectromagnetic interference (EMI). Selection of appropriate hardware for the operating voltagewill generally reduce or eliminate corona and gap discharges.Corona and gap discharges candevelop during service as a result of surface deposits or hardware damage. It may be necessary toevaluate the anticipated audible noise levels and the potential to interfere with communicationsignals during the design of high voltage transition facilities.
– Aesthetics: A transition facility may have the appearance of a single transmission pole or tower, orit may look like a substation. In siting a transition facility,viewscapes may need to be evaluated totry to assess and/or reduce visual impact.Screening， such as plantings or architectural features(walls，fences，etc.) may be required. It may not be possible to fully screen a transition facility,since the overhead line and dead-end tower should have appropriate electrical clearances from anyscreening.Depending on the voltage of the line,the height of the dead-end structures within atransition station can reach in excess of 30 m (100 ft). Visual screening should be evaluated forboth effectiveness and for long term electrical clearance issues(particularly for plantings).
– Electric and magnetic fields (EMF): Overhead lines generate both electric and magnetic fields.Underground lines generatc only magnetic fields due to the electric field being contained by thecable’s shielding.At an overhead to underground transition facility, electric fields will primarily begenerated from the overhead lines and cxposed buswork, if any.Magnetic fields will be generatedby the overhead lines, the underground cables and auxiliary equipment, such as shunt reactors.Because of the complex geometry at a transition structure，magnetic field calculations can becomplex. Techniques used to evaluate EMF at substations may be necessary to evaluate EMF attransition facilities.EMF may be a significant factor in the regulatory and environmental processfor site selection. There may be standards or guidelines for EMF levels on local, regional, andnational levels,and therc are some international guidelines. Local jurisdictions may haverestrictions on EMF levels generated by power lines in the vicinity of schools,daycare centers,hospitals,playgrounds,and residential areas. The International Commission on Non-lonizingRadiation (ICNIRP) has published voluntary guidelines for EMF Occupational Exposure. Thesevoluntary guidelines have been adopted by the World Health Organization (WHO). The AmericanConference of Governmental Industrial Hygienists (ACGIH) has published occupational thresholdlimit values for 60-Hz EMF. Compliance with the restrictions of local jurisdictions, the ICNIRPguidelines or ACGIH thresholds may be a necessary part of the siting process.
– Other community issues: There may be other community issues that could affect the siting of atransition facility. These may be possible to identify during the siting studies, or they may ariseduring the licensing of the line and/or the transition facility.