“High-Impedance Fault Detection” Revisited: Why the Term Has Lost Its Meaning and Should Be Abandoned

IEEE Transactions on Power Delivery · 2026-01-01

“High-impedance fault” is a commonly used term in power system literature with a decades-long history. While the term may be commonly used, it is not used consistently. This is especially true when one considers the disparity between usage in academic and industry contexts. In academic literature, the term is seldom defined explicitly, but appears to mean something like, “faults that are hard to detect.” When the authors informally survey practitioners, a common answer to the question, “What is a high-impedance fault?” resembles, “It is a fault with a high impedance.” While this is correct by way of tautology, it is unhelpful as a functional matter. Few practitioners or academics include multiple varieties of power system events that occur on operational circuits which might reasonably be called a high impedance fault, nor do they consider distinct and often differing characteristics of such events. Said differently, “high-impedance fault” is not a homogeneous class of events which can be considered uniformly, but a diverse set of power system conditions which share some characteristics and diverge substantially in others. This paper draws on over 40 years of practical experience and research in electrical characterization of normal and abnormal power system transients performed at the Power System Automation Laboratory at Texas A&M University to argue that the term “high-impedance fault” itself has become an impediment to developing techniques and technologies for detecting and mitigating a wide class of power system events which do not reliably operate conventional overcurrent protection devices.

Electrical phenomena associated with vegetation in contact with medium voltage conductors: summary of field experiments

IET conference proceedings. · 2025-10-14

Vegetation contact with medium voltage conductors is a major problem for many distribution network operators (DNOs) around the world. In addition to being a safety hazard and reliability concern, many DNOs are concerned about vegetation-induced teardowns of conductors igniting wildfires. Despite multiple controlled experiments performed at various laboratories around the world, many misconceptions persist about the electrical behaviour of vegetation contacting medium voltage conductors. This paper summarizes experiments performed by researchers at Texas A&M University and draws conclusions regarding the possibility of detecting vegetation contacts on active circuits.

Using high-fidelity waveform data to diagnose medium-voltage protection misoperations

IET conference proceedings. · 2025-10-14

Faults and failures are an unfortunate reality on power systems. In response, engineers have developed a variety of means and methods to protect power systems, with the ultimate goal of rapidly detecting and deenergizing circuits when a fault occurs while causing minimal impact to customers. Most of the time this process works reliably, but occasionally misoperations occur. While many microprocessor-based relays record oscillography as an auxiliary function, the quality and fidelity of the data vary substantially. Particularly during complex events, a lack of high-quality data can impede the investigation into the causes of protection misoperations, and their solution. This paper presents multiple case studies where high-fidelity waveform data was used to diagnose medium-voltage protection misoperations, and, in some cases, correct the underlying causes.

Utilizing high-quality waveform data to detect and diagnose protection misoperations and anomalies

IET conference proceedings. · 2024-04-08

Power system protection is designed to rapidly clear faults with the aim of improving safety and reliability. While the protection system generally functions as intended, it does fail from time to time. Few oversight systems exist, however, to verify the proper operation of system protection, or help diagnose misoperations when they occur. Researchers at Texas A&M University have developed an automated waveform analytics system which, in addition to other functionality, allows utilities to quickly observe when protection anomalies occur, and obtain information to aid in post hoc investigations.

Table of Contents

IEEE Industry Applications Magazine · 2023-04-06

Effective Use of Incipient Failure Detection

2023-03-27

Distribution circuits historically have operated in a largely reactionary mode: build strong circuits, using materials that generally last for decades; run to failure; make repairs. With limited exceptions, such as frequent inspection of key components, circuit owners lack practical alternatives.

Unintended Consequences of Extra Sensitive Protection

2023-03-27 · 1 citations

Exceptional weather events and conditions such as extreme wildfire ignition danger have caused some utilities to practice modification of protection settings to mitigate wildfire ignition and maximize safety. The most extreme example of this is a decision to fully de-energize circuits until dangerous conditions have passed. This practice in California for wildfire prevention is called Public Safety Power Shut-off (PSPS).

Online automated system for incipient fault and failure detection of distribution apparatus using waveform disturbances

IET conference proceedings. · 2023-07-04

Distribution network operators (DNOs) have historically operated their systems largely in run-to-failure mode. High value assets may receive some periodic inspection or maintenance, but most equipment remains in service until it fails, at which time it is replaced by the utility. Multiple decades of research have demonstrated that many failures can be detected from substation currents and voltages, allowing for proactive repair and remediation. This paper describes a system for the online collection, processing, and reporting of such events, as well as relevant examples.

Preventing Certain Powerline Caused Wildfires by Early Detection and Repair of Failing Devices

2022 · 4 citations

• Computer Science
• Computer Science
• Forensic engineering

Long-term drought and elevated environmental temperatures are contributing to a significant increase in the number and severity of wildfires in United States. One major west coast utility attributes 8-10% of wildfires to failures and faults on electric utility distribution circuits. Ignition mechanisms that can cause fires may develop over weeks or months before ignition occurs. Existing monitoring and protection systems cannot detect many incipient failure conditions before a catastrophic event causes fire ignition. This paper presents a real-time diagnostic technique capable of detecting developing fire ignition mechanisms. Operators can utilize actionable information, dispatching crews to find and fix certain developing ignition conditions prior to fire start. Actual case studies from utility trials are presented.

Incipient Electric Circuit Failure Detection and Outage Prevention Using Advanced Electrical Waveform Monitoring: Field Experience

IEEE Industry Applications Magazine · 2022-12-20 · 5 citations

Safe, reliable electric power is critically important in industrial facilities, including field production facilities and plants. The electric circuit protection and monitoring systems currently in use do not detect incipient faults or predict apparatus failures. Two decades of research demonstrate that early stages of apparatus, device, and cable failures can, in some cases, be detected electrically, enabling repairs and avoidance of faults and outages. The authors have developed a technology, which has become known as <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">distribution fault anticipation</i> ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DFA</i> ), that uses continuous monitoring to provide real-time situational awareness of circuit activity. The DFA system monitors voltage and current signals to detect circuit abnormalities and failures and utilizes intelligent algorithms to classify circuit events, including incipient failure signatures. This article provides examples of failing devices that were successfully detected in early stages. DFA technology was originally developed in cooperation with utility companies but is applicable to any power distribution circuit and has begun trials in an industrial setting.