7. EFC-400: Software for Simulation ofElectromagnetic Fields

Produced by High-Voltage Lines and Electric PowerSystems

Although most existing limits for electric and magnetic field strength are onlyrecommendations, utilities in some countries have already begun using these valuesto evaluate their power systems. Legislation is up and coming in many countries, andthe current guidelines will most likely become law in the near future. The EuropeanUnion plans to stipulate limits which the individual European countries can then eitheraccept "as is", or set even more restrictive limits. In Germany, new field strengthlimits took effect on January 1, 1997. Utility companies are now required to considerelectromagnetic radiation as part of their environmental compatibility tests. Existingfacilities must conform to the same law within three years. In the United States, moststates have adopted limits as well. Today, legislation in most countries is based onthe recommendations of the International Radiation Protection Association (IRPA).

In view of all this legislative activity, companies operating in the power sector must beable to compute and display the electric and magnetic field distribution for existingand planned equipment. WG's new simulation software package (EFC-400) is theideal tool for such advanced simulation work. EFC-400 runs under Windows,producing professional-quality results with simple operation and fast processingspeed.

The software libraries include different tower types, cables, insulators, buildings andindividual elements so that users can simulate non-standard towers and otherobjects. User-defined entities can then be added to the EFC-400 libraries, making iteasy to simulate power line routes. The towers forming a route can be inserted intoimported terrain profiles or maps (vectorized) with a simple mouse-click. EFC-400 isbased on the same principles and uses the same formats as CAD software andgeographical information systems (GIS), thereby reducing the learning time for usersfamiliar with such concepts.

Each time a parameter is changed (e.g. cable sag, mast spacing), the fielddistribution can be recomputed and displayed. The power line route can also bemanipulated as a whole (with functions such as shift, rotate, insert, etc.). The cablesare automatically adjusted with each change.

While magnetic fields penetrate almost all media unchanged, electric fields aregreatly influenced by towers, buildings, vegetation, etc. The software takes intoaccount the ground cable and mast influences and also simulates buildings toprovide an excellent approximation of the actual field strength.

EFC-400 computes the field distribution in the range 0 to 500 Hz. To comply withmost norms and guidelines, the existing background field strengths must be takeninto account. Accordingly, the software handles multiple field sources with properphase and includes them in the overall simulation. The simulation can thusencompass railway power systems (e.g. 16 2/3 Hz), high-voltage lines at 50/60 Hz or

d.c.-based street car or subway lines. During the test phase, the software was alsodeemed suitable for simulating fields produced by transformer facilities. With thesoftware's 500 Hz upper limit, the on-board power systems in airplanes and shipscan be simulated. Most of these systems operate at 400 Hz.

EFC-400 is a versatile tool which utility companies will find ideal for their planningrequirements. The software makes it easy to compute electric and magnetic fieldstrengths for verifying conformance to limits, assuring electromagnetic compatibilityand assessing human safety factors.

The result presentation facilities are also very powerful. Field strengths are computedand displayed with respect to the actual topography. Measurement data (e.g.produced by EFA-3 Field Analyzer) can also be projected into the topography.Queries received from consumers or other parties are also easily handled since EFC-400 can output results for single cases in protocol format. Users can thus generateall-encompassing data as required by authorities during the approval process.

Werner Kumbier