Large electromagnetic models often require the simulation of many operating conditions, fault locations, and network topologies. In conventional workflows, each variation of the network generally requires a separate solution, resulting in long computation times for large networks. The Devices capability available in MultiFields provides an efficient alternative by segmenting the entire network into multiple regions consisting of the detailed target region and the surrounding network regions. This approach is carried out by allowing multiple device states and scenarios to be evaluated from a single run. In this article, we present a practical workflow for analyzing large networks using devices and the new Device Editor available in SESCAD. We first review how device behavior can be defined graphically using the Device Editor and then demonstrate how large peripheral network regions and various target fault locations can be represented as devices connected to a detailed central region, which is the area of focus in the study. The approach is illustrated through a “Monitor Fault” study involving substations, transmission lines, and a parallel buried pipeline. Finally, we show how the same methodology can be used to evaluate different peripheral network topologies without repeating the complete simulation.

This article presents the application of a new CDEGS capability for modeling pipe-type cables with non-conductive enclosures in AC interference studies. Using a typical Right-of-Way (ROWCAD) example familiar to users, a coated pipeline running parallel to overhead transmission lines is modeled inside a non-conductive enclosure and compared with the original representation in which the pipeline is directly buried in soil. Equivalent models are analyzed in both Right-of-Way and MultiFields to compare the resulting interference predictions. The results identify the conditions under which explicit modeling of non-conductive enclosures is necessary and demonstrate how this new capability extends existing analysis approaches.

This paper presents the application of the MultiFields Ultimate software package for the full-wave analysis of a power transformer. The analysis considers a complete three-dimensional model of a transformer based on actual dimensions and material properties. The method takes advantage of modeling high-permeability laminated plates, enabling an accurate representation of the transformer core. A single-phase power transformer is modeled in SESCAD and analyzed using the HIFREQ computation module to evaluate its electrical performance. The results demonstrate that it accurately predicts the expected voltage and current characteristics of the transformer. Furthermore, the full-wave approach allows the extraction of key transformer parameters, including short-circuit and open-circuit characteristics, providing an alternative to measurement-based methods.

In addition, the magnetic field distribution in the surrounding region is investigated under short-circuit conditions, both in the presence and absence of a magnetic shielding structure. The capability of MultiFields Ultimate to perform full-wave analysis of transformers in their actual physical configuration is particularly important, since such devices may generate substantial magnetic fields in their surrounding environment. This makes HIFREQ a suitable tool for field assessment and compliance with existing standards and guidelines.

We review practical aspects of using wideband transformers, which are available in CDEGS software packages, to represent two-winding power transformers. First, the methodology is briefly reviewed to provide enough background to understand the two-winding wideband models. Then, several practical examples (including example files) are provided to facilitate easier adoption of the available wideband models by practitioners.

CDEGS has demonstrated its versatility over many years. One of its lesser-known capabilities is antenna modeling. In this article, we use that capability to examine electromagnetic interference from antennas and its effects on drones using the MultiFields software package. A high-directivity antenna operating at 2.4 GHz is used to focus electromagnetic fields on a consumer drone. Quantities such as induced potential rise, current, and voltage on the drone are analyzed at various transmission distances, demonstrating that this type of analysis can be carried out in CDEGS. The article focuses on the feasibility of such analyses. Results show the expected trends under different conditions, and a transient study is also presented to provide another realistic representation of the problem. The findings of this investigation, together with previous antenna-related work carried out by SES, suggest that antenna studies are feasible using CDEGS.

MODELING VS. MEASURING: CURRENT SPLITS DISTRIBUTION
WITH TRANSMISSION AND DISTRIBUTION SUBSTATIONS

Brandon Dobrowski, P.E.
Safearth Americas, Corp
safearth.com

When a substation ground grid is designed whether for a greenfield site or a brownfield location, one important parameter that is slowly being accepted as part of the design is the split factor. Historically, there have been methods to approximate what the split factor is based on specific conditions. More recently, computer programs such as CDEGS and the FCDIST module have been used to estimate more accurately what the split factor will be. How does the distribution system get modeled to get the split factor? Is it considered or is just transmission considered for determining the split factor for the design? How does a model compare to measurements? What are the difficulties in modeling and difficulties in measuring? What are the benefits? This article will look at modeling distribution and transmission systems to determine the split factor and how it compares to completing current injection testing that measures the split factor in real time.

IMPLICATIONS OF GROUNDING & BONDING PRACTICES BETWEEN UTILITY OWNED SUBSTATIONS AND LARGE LOAD CUSTOMERS

Joseph (Tony) Arnold | Aleen Mohammed

This paper will show how SES CDEGS grounding software modules were used to illustrate the impacts of typical grounding and bonding for MV Cable Power cables between separately owned grounding systems. The intent of this paper is to spread awareness of the implications of grounding and bonding techniques, and to make the user better aware of the impacts associated with transferred potentials. Representative models were developed based on real world applications to better understand how system fault current levels, grounding system separation distances, and MV cable bonding techniques impacted transferred step/touch potentials and equipment rating requirements.

ANALYSIS AND DESIGN OF GROUNDING SYSTEMS IN
HIGH-RESISTIVITY SOILS FOR LARGE ELECTRICAL INSTALLATIONS

Camilo Marconetto
Estudios Eléctricos
estudios-electricos.com

This paper presents the modeling and simulation of large-scale grounding systems applied to wind farms, photovoltaic plants, and battery energy storage systems (BESS). Specifically, in the present paper a wind farm is analyzed using specialized software MALZ that accounts for soil characteristics and metallic structures, and the results are compared with those obtained from conventional software commonly used for substation grounding design MALT. Simulations were carried out under defined operating conditions, and the results were validated through field measurements performed after construction of the grounding grid. The study underscores the limitations of conventional tools and advocates the need for specialized simulation software to enhance design accuracy, reduce electrical risks, and optimize project costs.

LOCALIZED TOUCH VOLTAGES AT FAULT INJECTION
POINTS IN A LARGE 230/115 kV UTILITY SUBSTATION

Jeff Nunn
MCW/AGE Power Consultants
mcw.com

This paper examines localized touch voltage behavior in a large 230/115 kV utility substation and its implications for conventional grounding study assumptions. Using detailed CDEGS simulations, it is demonstrated that peak touch voltages can increase by at least approximately 25% relative to equipotential assumptions, depending on fault current injection location. The results show that localized voltage gradients can challenge common assumptions regarding equipotential grounding systems and locally circulating currents. The findings highlight the importance of evaluating multiple credible fault locations using explicit current injection models to ensure accurate representation of system behavior and protection of personnel.

STEP VOLTAGE MITIGATION USING SKIRT GROUNDING

Jerson Alex
MCW/AGE Power Consultants
mcw.com

This paper examines the use of skirt grounding as a practical mitigation technique for reducing external step voltages near substation perimeters. The study presents a greenfield substation where the initial grounding design achieved acceptable GPR and touch-voltage performance; however, elevated step voltages remained in accessible areas outside the station fence without insulating crushed rock coverage. Several mitigation approaches were evaluated, including longer ground rods, ground wells, insulating crushed rock, and skirt grounding. The optimized skirt grounding configuration successfully reduced the perimeter step voltages below the allowable safety limit.

IMPRESSED VOLTAGE EARTHING ARRANGEMENT
FOR STEEL PIPE CONTAINED UNDERGROUND CABLE

Kumar Manglam | William Penrice | Travis Eaton
Kieran Millar | Abhinandan Mishra | Himanshu Negi
Arcadis Consulting (UK) Limited
arcadis.com

This paper presents a comprehensive assessment of the impressed voltage and earthing requirements carried out for a utilities client on two 132 kV substations, to ensure human safety during asset replacement works of an existing underground 132 kV cable contained within a steel pipe that is buried beneath the ground. Using the CDEGS modules of SPLITS, TRALIN, MALZ, HIFREQ & SESCrossSection; modelling and simulation of real-life fault scenarios were compared and analysed. The studies evaluated earth potential rise (EPR), touch voltages, and body currents under various fault scenarios, including configurations with coated steel pipelines connected to the main earthing systems. The results demonstrate significant variation in EPR and body current exposure depending on pipeline coating, network configuration, and mitigation measures. Findings indicate that, while most working scenarios present low risk (body currents within IEC 60479-1 AC-2 zone, typically resulting in only perception or startle responses), certain configurations—particularly with coated pipelines—can result in higher body currents falling into the AC-3 zone, which can cause strong involuntary muscular contractions. The CDEGS Human Body Model was utilised to evaluate worker safety and ensure at all times during the work the impressed voltage on the worker does not exceed the safe permissible limits for body current. The effectiveness of surface laid mitigation solutions were presented using temporary operators earth mat and bracket earthing to reduce the resultant current and provide safe working environment during substation maintenance activities.

A CASE STUDY IN AC CORROSION RISK MODELING AND
FIELD VALIDATION ON A NEWLY CONSTRUCTED PIPELINE
PARALLELING A 345 kV TRANSMISSION LINE

Nafiz Imtiaz, P.Eng.
Commonrow Consulting

This case study describes how a CDEGS model, anchored to a single remote monitoring unit (RMU) and to routine cathodic protection (CP) survey readings of AC pipe-to-soil voltage, was used to address two concerns raised by the operator of a recently constructed FBE-coated pipeline paralleling a 345 kV transmission line. A substantial AC mitigation system was already in place at the time of the investigation, including solid-state decouplers, horizontal gradient control wires, and one RMU. Despite this, the RMU recorded an instantaneous AC current density (ACCD) reading exceeding 213 A/m² together with an electrical resistance probe corrosion rate of 5 mil per year at a location that the original design-stage interference study had not identified as a hotspot. The operator therefore sought to determine (a) which other uninstrumented locations along the corridor might be similarly affected and (b) the maximum ACCD the corridor could plausibly experience. The model was anchored against the RMU and CP survey AC voltage readings (predicting about 43.5 A/m² at the RMU versus a measured peak-load monthly average of about 40 A/m²) and then used to scan the corridor. Two additional hotspots were identified that could not have been found by spot field measurements alone. Because the four-month window time weighted average ACCD of about 22.7 A/m² sat below the 30 A/m² AMPP/NACE SP21424 2018 monitoring threshold but was drawn from a winter to spring window rather than a full annual cycle and included individual peak load months above 30 A/m², the recommended mitigation pathway was a staged one. Continue operating the existing RMU through the warmer months not yet sampled and deploy additional RMUs at the model identified hotspots in parallel, so that a full annual cycle of measurements can be assembled at all three locations and install gradient wire grounding only where the resulting long-term data confirms a persistent exceedance pattern.

EMI IN CROSSING LINES:
CDEGS AGAINST CONVENTIONAL EMT APPROACHES

Stelios Papadakis | Dimitrios Chatzipetros
Hellenic Cables
hellenic-cables.com

This paper investigates electromagnetic interference (EMI) phenomena in crossing energy lines between buried or above-ground metallic structures, such as pipelines and power cables. Emphasis is placed on the influence of crossing angle between crossing entities on the resulting induced voltages. Two modeling approaches are compared: simplified electromagnetic transient (EMT)-type simulations based on parallel segment approximations, and thorough Method of Moments (MoM) simulations using CDEGS. The EMT-type approach follows the recommendations of CIGRE TB 95 for modeling inductive and capacitive coupling mechanisms via equivalent parallel exposures, while CDEGS enables accurate modeling of real crossing geometries accounting for the original field equations. The results indicate that EMT-type methods provide acceptable accuracy for near-parallel configurations while maintaining accuracy for crossing geometries; however, hard efforts are required to achieve acceptable accuracy due to the required detailed discretization. Additionally, CDEGS simulations demonstrate that even small deviations from orthogonality may lead to significant induced voltages. Sensitivity analyses are performed for different bonding configurations, including open, single-point, and solid bonding of the metallic components involved. The results highlight the importance of accurate geometric modeling in EMI studies and provide practical insights for engineering design and risk assessment.

ELECTROMAGNETIC FIELD COMPLIANCE
STUDY FOR NEW OVERHEAD LINE DESIGN

Himanshu Negi¹ | Kumar Manglam¹ | Nuno Silva¹
Colin Thompson² | Kieran Millar¹ | William Penrice^1
1Arcadis Consulting (UK) | ²SSEN Transmission
arcadis.com

This study presents a high-fidelity modelling approach for electromagnetic field (EMF) compliance in 400 kV overhead line (OHL) design, using advanced simulation tools based on full-wave solutions of Maxwell’s equations to capture three-dimensional electric and magnetic field interactions. Occupational exposure at 400 kV towers was evaluated for both double and single-circuit energisation. This study represents the first comprehensive analysis of duck-under scenarios at OHL crossings, providing detailed insights into EMF behaviour under complex multi-voltage configurations. Results show that 400 kV circuits dominate EMF exposure at duck-under crossings with lower voltages, mainly when lower clearance applies; if the overpassing line is much higher, the lower line can dominate ground-level fields. The magnetic fields governed by current flow. Parametric studies highlight that optimised phasing and increased clearance are essential for reducing electric field, while magnetic fields show only minor sensitivity to conductor sag. Both real sag and average design sag were considered to capture operational conditions. Conductor radius reduction further mitigate electric fields, whereas crossing angle has negligible impact compared to clearance and phasing optimisation. This advanced modelling approach ensures regulatory compliance and supports robust design.