At a glanceSiemens Power Technologies Interna-tional (Siemens PTI) can support oper-ators of high-voltage systems with thefollowing services:

· analysis of the compliance to limitsfor time-varying electric and mag-netic fields in the vicinity of conduc-tors, transmission line routes,switchgears and power plants

· calculation of the inductive interfer-ence between high-voltage over-head lines and secondary equip-ment or pipelines

· proposal of measures to ensureelectromagnetic compatibility ofhigh-voltage switchgears

The challenge

Electromagnetic fields (EMF)Current-carrying conductors generatea magnetic field in their vicinity, andenergized conductors generate anelectrical field.

These electromagnetic fields (EMF) canproduce adverse health effects if theyexceed certain limits. Exposure limitsare described in many scientific studiesand are discussed politically all aroundthe world. The International Commis-sion on Non-Ionizing Radiation Protec-tion (ICNIRP) published guidelines for

limiting exposure to time-varying elec-tric, magnetic, and electromagneticfields. Nevertheless, some countriesdemand compliance to much lowerexposure limits than those required byICNIRP. The operators of electrical sys-tems are committed to verifying com-pliance with the guidelines, providinga documented evidence of conformityto the respective exposure limit values.

Figure 1: EMF-calculation model of a highvoltage station.

Power frequency interferencePower frequency electromagneticfields from overhead lines and cablescan induce voltages on secondary ca-bles or metallic pipelines situated inparallel. On the one hand, these volt-ages can be a risk for people workingon the equipment, and on the otherhand, the equipment itself can bedamaged. Therefore companies shouldcomply with the limiting values.

Transient overvoltages in secondaryequipmentHigh frequency electromagnetic fieldslike those that appear during switchingof circuit breakers or disconnectors cangenerate high transient overvoltagesin secondary equipment. The second-ary equipment can be disturbed oreven damaged due to high voltagepeaks.

Our solution

Electromagnetic fields (EMF)High performance software allowsSiemens PTI to calculate the EMF in theproximity of single conductors, substa-tions or power plants.

Figure 2: Calculated magnetic flux density inthe proximity of a high voltage station.

With these programs, magnetic fieldsare calculated according to the Biot-Savarts law. The evaluation of electri-cal fields is realized considering thecharge simulation method.

For the optimization of single electricalequipment, and within the scope offault investigations, detailed EMFsimulations can be realized with thefinite element method.

For existing installations, the proof ofcompliance with reference levels canalso be provided by measurements onsite.

Interference and electro-magnetic field analysisStudies for the calculation and evaluationof electromagnetic fields and theinterference of secondary equipment andmetallic pipelines

Substation boundary

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If the simulations or the measurementsshow that the limit values are exceed-ed, Siemens PTI can propose correctivemeasures.

Power frequency interferenceFor the simulation of the electromag-netic interference in secondary equip-ment and in pipelines due to high volt-age overhead lines, Siemens PTI canrely on high-performance calculationprograms.

Figure 3: Interference analysis model of over-head line and induced pipeline.

Not only parallel courses betweenhigh-voltage overhead-and secondaryconductors or pipelines can be mod-eled, but also oblique exposures andcrossings.

The interference analysis takes into ac-count the maximum load as well as theshort-circuit currents in the overheadline.

Transient overvoltages in secondaryequipmentThe occurrence of inadmissible, high-transient overvoltages in secondaryequipment during switching opera-tions can be avoided with an EMC-(Electromagnetic Compatibility) com-pliant design. For this purpose SiemensPTI can plan EMC-compliant measures.

The effectiveness can be tested withEMC measurements according toEN60694.

Application example 1

Magnetic field calculationFor a newly constructed 380/110 kVsubstation, the conformity to the ref-erence levels of the German26.BImSchV was required. A three-dimensional model of the station wasbuilt (Figure 1) and the power fre-quency electric and magnetic fieldswere calculated. Figure 2 shows thatthe magnetic flux density in the public-ly accessible area outside of the stationis significantly below the referencelevel of 100 µT. The electric fieldstrength is below the reference level of5 kV/m.

Application example 2

Pipeline interferenceA gas pipeline was constructed parallelto an existing 380 kV overhead line(Fig. 3). The inductive interference ofthe pipeline due to maximum load andshort-circuit currents in the overheadline was analyzed. The calculationsdemonstrated that in case of an earthfault, the limit value of 1000 V wouldbe exceeded significantly. Correctivemeasures were planned and coordi-nated with the cathodic protection ofthe pipeline to meet the demandedinterference standards (Figure 4).

Figure 4: Calculated interference voltage pipe-line – earth

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Published bySiemens AG 2017

Energy Management DivisionFreyeslebenstrasse 191058 Erlangen, Germany

For more information, please contact:power-technologies.energy@siemens.com

AL=N, ECCN=EAR99Subject to changes and errors. The infor-mation given in this document only con-tains general descriptions and/or perfor-mance features which may not alwaysspecifically reflect those described, orwhich may undergo modification in thecourse of further development of theproducts. The requested performance fea-tures are binding only when they are ex-pressly agreed upon in the concluded con-tract.