The CDEGS software package (Current Distribution, Electromagnetic Fields, Grounding and Soil Structure Analysis) and its various subpackages have been designed to analyze problems involving electromagnetic fields, electromagnetic interference, and grounding with a global perspective, starting literally from the ground up.
Quite often, however, our customers are not sure which package or engineering modules they need.
The following technical papers and documents should help you to refine the selection of the most appropriate software package for your needs. If you have not already done so, please use our Software Selection Wizard to determine the optimum package that best fulfills your requirements. For a quick estimate of the appropriate software package you can also use the quick decision tree shown below. If you are still unsure, please contact us.
This paper examines a few methods used in grounding analysis and illustrates the advantages, limitations, and the applicability of these methods. Computation results using these methods are presented and compared. The various cases modeled in this paper include grounding networks of different sizes, grounding networks with buried metallic structures such as steel pipes, and high frequency cases. The discussions and conclusions given in this paper can be used as a reference when deciding which method should be used to carry out an accurate and efficient grounding analysis.
The range of applications that can be handled by the low frequency grounding analysis software packages (such as Autogrid Pro, AutoGround, MultiGround and AutoGridDesign) that use the MALT computation program module and the other software packages that support higher frequencies (such as MultiGroundZ or MultiFields) that use the MALZ or HIFREQ computation program modules overlap: they can all be used to compute the touch and step voltages around a grounding grid buried in a uniform or arbitrary soil structures (MALT and MALZ can handle multilayered or arbitrary soil structures, as we all know) as well as the GPR and impedance of the grid. This raises the following questions:
This article discusses those questions both qualitatively and quantitatively, using buried grids of various sizes as an example. Section 2 describes the assumptions and limitations of the various programs in general terms. Section 3 then describes the physical system that was studied to compare the three programs quantitatively. Finally, Section 4 presents some numerical results.
Three independent tools are available in the SES software packages to carry out an AC interference study: SESTLC, ROW (TRALIN/SPLITS) and HIFREQ. To help select the best program for your study, it is important to be aware of the advantages and limitations of the different tools.
The objective of this article is to have an overall look at those three tools and illustrate their advantages, limitations, and applicability.
This paper studies the electromagnetic interference problems arising in corridors shared by transmission lines, pipelines, and railways, etc. A new circuit model method for analyzing interference problems is introduced. This method can be used to compute the combined inductive, capacitive, and conductive interference level efficiently and accurately. Practical examples are examined and results obtained using the new method are presented and compared with those obtained using the conventional circuit model method and the exact electromagnetic field method. It is shown that the new circuit model can be applied to problems which cannot be solved using the conventional circuit model.
AC interference caused by high voltage power lines on non-energized utility lines (such as pipelines, rail tracks, etc.) sharing a common corridor with the electric lines is a serious concern because it can result in electric shocks and can threaten the integrity of the utility lines. This paper compares and discusses two different methods devoted to AC interference studies. A circuit approach and an electromagnetic field approach are used to carry out a parametric analysis for various configurations of the network, grounding systems, fault current contributions and locations, and soil structures. In the circuit approach, inductive and capacitive interference components are computed first and independently from the conductive components. The overall interference is then obtained by adding all components. Two methods are used to model ground impedances with the circuit approach. The coupled-ground method accounts for the coupling between grounds and the classical method ignores the coupling by assuming that each grounding system is very far from all others. On the other hand, the electromagnetic field theory approach models the complete network and the inductive, capacitive and conductive interference effects are simultaneously taken into account. Computation results based on the various approaches and methods are then compared and discussed. Noticeable differences are found in some cases between the various approaches.
This paper proposes a new method, the Strip Simulation Method, for computing the electric field on the surfaces of conductors for power transmission systems. This method can also compute the electric field at any observation point in space. The effects of earth surface also have been taken into account. The computation results have been compared with those obtained using the well known successive image theory. The comparison of the results obtained for bundles of four conductors show that when the ratio of the conductor radius to the distance between conductors is greater than 1, the two methods give similar results. When it is smaller than 1, the Successive Image Method tends to overestimate the minimum gradient on the conductor for bundles with more than 2 conductors and the proposed method gives accurate results. A practical case of a transmission line has been studied in this paper. The electric fields on the conductor surface and at the earth surface have been computed. In this case, the proposed method and the image method give consistent results.
An efficient method for computing magnetic fields generated by transmission lines is presented. The method uses a two-dimensional computation approach and gives both conductor based and phase based line parameters as well as the magnetic field. The computation results for a typical case are compared with those obtained using an independent three-dimensional analysis software and it was found that the results are in good agreement.
SES offers two software products that calculate voltages transferred from energized power lines to non-energized metallic conductors, such as de-energized power line circuits under maintenance, pipelines, railways, communications cables, fences, etc. In both cases, the software accounts for magnetic field inductive coupling, electric field capacitive coupling and through-earth conductive coupling. These two products, MultiFields and Right-of-Way Pro, are compared in this short article.
Measurement of the grounding system impedance of a substation or power plant is often required immediately after construction, in order to verify that the design calculations correctly predict the performance of the system. Years later, new measurements are sometimes required to check that the performance of the grounding system has not deteriorated. This type of measurement, however, which is typically carried out using the fall-of-potential method, is plagued by a number of potential problems: conductive coupling between the grid under test and the remote current return electrode, especially for soil structures with low resistivity over high; inductive coupling between current and voltage test leads; inductive coupling between test leads and grounding grid conductors; inductive coupling between test leads and power line static or neutral wires; additional grounding provided by power line static and neutral wires, which lowers the apparent impedance of the grounding grid. This paper presents a methodology for measuring ground impedances that minimizes the effects of inductive coupling, conductive coupling, and power line grounding. A parametric analysis is carried out to illustrate how measurement error changes as a function of grid dimensions, soil structure, test electrode locations, test lead separation distance, locations of test lead connections to the grounding grid, and test signal frequency used. It is found that accurate ground impedances can be obtained by interpreting the test data using electromagnetic field models that determine the expected error as a function of test signal frequency.
This paper discusses the analysis of an overheating problem which has been observed within a 140’ (43 m) long steel pipe casing containing 115 kV three-phase electric power cables. A steel casing electromagnetic field model has been built to determine the induced current (eddy currents) distribution along the radial, transverse, and longitudinal directions of the casing caused by the energized cables under different operating conditions. This model takes the combined effects of the inductive, conductive, and capacitive interference into account. This study involved a circuit model to determine the voltage and current distributions in the conductors of the buried power cables. Furthermore, a detailed analytical model of the cylindrical steel casing (assuming an infinitely long casing) was conducted to determine the actual paths of eddy current flow and their density throughout the cross section from the inner surface to the outer surface of the steel casing. The computation results show that induced currents in the steel casing can cause significant heat losses and that the exact distribution of the induced current density within the steel casing plays a crucial role in the heat losses generated by such currents.
This paper presents a case study of a satellite communications site at which equipment was damaged during a lightning storm. The transient ground potential rise (GPR) and stress voltages on the damaged equipment (HPA) during a lightning storm are obtained using the electromagnetic field theory method. The stress voltage on the HPA is reduced by 75% (from 25 kV to 6 kV) when the isolated signal ground wire is electrically bonded to a nearby equipment ground. An extended grounding system has little influence on the stress voltages at the beginning of the transient period; however, it reduces the stress voltages significantly (by about 50%) after the first 3 µs.
This paper discusses in detail the computation of the transient ground potential rise (TGPR) in a 500 kV circuit breaker (CB) in a gas-insulated substation (GIS) during phase-to-ground faults. The faults are caused by a lightning strike on the phase conductor or a disconnect switch operation in the GIS. Models based both on electromagnetic fields and circuit theory have been used to predict the transient response. A reasonable agreement between the circuit model and field theory approaches is found in the presence of the grounding grid. The TGPR and transient electromagnetic fields near the CB exhibit an oscillation similar to that observed in the absence of the grounding grid . The amplitude of the oscillation is reduced by about 50% due to lower surge ground impedances at the fault site. For the disconnect switching surge scenario, the transient GPR and electromagnetic fields oscillate initially at a higher frequency (around 1.8 MHz). The oscillation shows a very different waveform compared to the one for the lightning surge scenario. Two mitigation methods have been applied to the TGPR in the lightning surge scenario. It is found that the TGPR can be reduced significantly (as much as 40%) when the length of the ground strap of the circuit breaker is reduced by about a factor of two.
The TLC software package is a Transmission (and distribution) Line Calculator for rapid EMF, line parameter, and induced voltage estimates. It can be used to quickly estimate line parameters, electric fields,and magnetic fields associated with arbitrary configurations of parallel transmission and istribution lines. It also estimates induced voltages and currents on other parallel metallic utilities, such as pipelines and railways.
The problems associated with corona in high voltage (HV) lines greatly influences the dimensioning of conductors, insulators, and fittings. To arrive at a feasible solution, it is necessary to estimate both the line conditions once in operation and the acceptable values ranges. The three main corona criteria are Radio Interference (RI), Audible Noise (AN) and Corona Loss (CL). RI and AN affect mostly the environment and the cost related to the transmission line construction. Conversely, corona loss affects mainly operation cost. The new SESEnviroPlus software package is an analysis tool developed for the design of overhead AC and DC transmission lines. Its user-friendly interface is of great help in rapid line design.
The AutoTransient program simplifies the analysis of transient phenomena by automatically running the programs, using the computation frequencies recommended by the Fast Fourrier Transform as input to the frequency-domain software packages until some specified termination conditions are met. This article summarizes the capabilities of the program and describe describe a simple but complete transient study using AutoTransient.
- Electrically Small grounding systems i.e., classical equipotential assumption. This choice includes an automatic grid design module.
Uniform or two-layer Horizontal soil structures
- No fault current split calculation:
- With simple fault current split calculation:
Complex soil structures(multilayer with finite trapezoidal volumes, cylindrical inclined, hemispherical and hemispheroidal soil layering)
- With simple fault current split calculation:
- With simple and complex fault current split calculation with capacitive and inductive (excluding conductive) interference studies
- Grounding systems of any length and complex soil structures (non-equipotential grounding systems)
- With simple fault current split calculation:
- With simple and detailed fault current split calculation
- Complex systems, including buried conductors, pipe-enclosed multi-conductor cables:
- Overhead conductor systems (no concentric cables):
- With estimated electromagnetic field levels, radio and audible noise and corona-related analysis:
- With estimated electromagnetic field levels
- Complex systems
- Simple radial topologies
- Electromagnetic Field Based Analysis
- Circuit Model Based Analysis
- Right-of-Way Pro
- Estimate of AC Interference Levels (also provides EMF calculation for overhead lines and line constants)
- SESTLC Pro
- Accurate solutions for simple or complex systems , including aboveground and buried conductors, up to 1 GHz:
- MultiFields or MultiFields+ or MultiFields Pro
- Electrical Environmental Studies
- Estimate of electromagnetic fields under transmission lines
- MultiFields or MultiFields+ or MultiFields Pro