This article shows how to embed the fault current split calculation into a MALZ grounding system model, based on two initial FCDIST simulations, dispensing with the need to revisit FCDIST after modifications are made to the grounding system model or soil structure. Both the theory, based on Thévenin equivalent circuits, and detailed instructions are presented.

For three-phase, three-winding transformers that have a tertiary delta winding, zero-sequence tests are typically performed with the delta winding in place. Results from such tests are affected by the circulating currents formed in the delta winding. To use the resulting impedances in a computer model based on the T-equivalent circuit, one must convert such data into parameters suitable for simulation. In this article, formulae for such transformations are derived from the typical zero-sequence tests setup vs. the desired zero-sequence tests setup. The methodology is applicable to star-star-delta as well as auto-star-delta configurations.

Procedures to create circuit models in HIFREQ and calculate their sequence components are described. The sequence components obtained with the provided methods can be used to validate the results from the corresponding TRALIN model or data in manufacturer datasheets. Moreover, more complicated and realistic circuit models can be created in HIFREQ, such as networks including metallic plates or other types of system configurations that cannot be represented by the parallel conductors or cables used in TRALIN models. The presented methods provide more flexibility to calculate sequence components for this kind of system.

Running rails used as a return conductor and grounded or ungrounded schemes have been widely adopted in DC traction power systems. Ideally, all the current should return through the rails. But due to the resistances of tracks and insulation deterioration between tracks and track slab, there will be a portion of the return traction current that leaks from the intended path (i.e. running rails) called stray current. This stray current can cause serious problems by accelerating the corrosion process of a buried pipeline and other metallic structures located near the DC traction system.

This article describes and discusses investigations of typical physical models of the DC traction systems, including medium-voltage direct current (MVDC) railway electrification system (RES) and DC light rail transit (DC-LRT). Rail potentials and stray currents were calculated for different scenarios, accounting for dynamic, real-time traction conditions. The corrosion trend of stray current is quantitatively calculated, and the corrosion rate of stray current is evaluated. Furthermore, an impressed current cathodic protection (ICCP) system is designed, and its effectiveness is verified considering the non-linear polarization process. The results show that CDEGS can quantitatively calculate and predict the mass loss of buried metal caused by DC traction stray current corrosion, and cost-effective CP design can be achieved.

The localization of grounding grid conductors is essential to diagnosing their status. In this work, a novel remote electromagnetic device capable of locating and mapping grounding grid conductors is developed. The electromagnetic field method is used, and the detection of the target conductors is obtained based on the responses of the sensing coils contained on the developed device. This remote grounding conductor detection device can be a good candidate for assessing the performance of grounding grid systems, including their integrity and boundaries.

Modeling a train tunnel boring underneath an existing substation can be performed using CDEGS MALZ software. This article presents the high-level process of doing so and demonstrates available adjustments that can be made to make the computations to work.

CALCULATIONS OF RESISTIVE POWER LOSSES IN
METALLIC MATERIALS EXPOSED TO MAGNETIC FIELDS

Yuhan Wu, Eng.
Hydro-Quebec
hydroquebec.com

This article presents the development of a human analog model composed of realistic, tissue-like materials that closely replicate human anatomical structures. The model is designed to evaluate electrical safety across a wide range of contact scenarios and environmental conditions. It has been calibrated to align with the outcomes defined by the IEEE standard for electrical safety, ensuring accuracy under all conditions where the standard is applicable. Notably, the model’s utility extends beyond the standard’s scope, enabling safety assessments in complex or atypical situations—such as for submerged individuals or in environments with shallow soil layers—where traditional standards fall short.

This article introduces a strategy for defining a Fictitious Main Path in Right-of-Way (ROWCAD), freeing the main path from being any single physical line. Instead, this path can be constructed from entirely new or combined coordinates, enabling optimized region matching and improved circuit modeling in complex network configurations. Through detailed explanation and visual illustrations, we outline the method's guiding principles and demonstrate its practical benefits across multiple use cases.

This article presents a new signal type in SESTransient designed for modeling signals consisting of harmonics directly from spectral input. Previously, it was possible to construct harmonic signals manually using multiple HIFREQ runs and carefully scaled energizations, followed by signal synthesis in FFTSES. This method, while theoretically rigorous, was time-consuming and prone to error. The new signal type simplifies this process by allowing users to define harmonic spectra explicitly and apply them as time-domain excitation. The article reviews the manual method and its theoretical basis, then details the implementation and use of the new feature, which improves modeling accuracy and usability for harmonic studies in SESTransient.

This paper highlights the importance of windowing and preprocessing techniques in SESTransient workflows and promotes greater awareness of spectral leakage phenomenon among practitioners. In doing so, it bridges a gap between signal processing fundamentals and their practical application within the SESTransient analysis framework.

Significant substation upgrades were being made to a client’s substation including the addition of current limiting reactors to reduce fault current magnitudes. Due to the substation expansion, a grounding analysis was needed to design a touch and step voltage compliant grounding system. During this investigation three major water mains were identified as being located between the focus substation and the neighboring transmission substation owned by another entity. Concerns were raised about possible shock hazards on the water pipeline infrastructure during a fault at either of the substations. This paper describes the overall project layout, concerns, analysis, and overall mitigation approach. From start to finish this was a multiyear project involving three separate utilities with significant coordination between the three.

AC INTERFERENCE ANALYSIS OF AN ELECTRICALLY CONTINUOUS GATHERING PIPELINE SYSTEM - A CASE STUDY

Casey D. Heinrich
Corrpro
azuria.com/corrpro