MV/HV Circuit Breaker Testing Beyond Conventional Practices

Volney Naranjo, Megger Fall 2021 Industry Topics, Industry Topics

Conventional testing of medium- and high-voltage circuit breakers (MV/HV CBs) involves measuring the timing and travel of the main contacts and their corresponding resistors (pre- or post-insertion) if any, along with the current profile of the operating coils, and occasionally the timing of auxiliary contacts. This article explains several techniques available to improve or extend the scope of testing. Aspects …

How Grounds Affect Peak Voltage Due to Lightning

Al Martin, retired Industry Topics, Fall 2021 Industry Topics

Did you know that the most common characterization of a ground rod may not work for lightning? In 1997, an experiment at the International Center for Lightning Research and Testing (ICLRT) at Camp Blanding, Florida, challenged the predominant view that ground rods are essentially resistive. That experiment found that the waveshapes of lightning currents in a building grounding system and those entering the electrical …

Electrical Safety through the Lens of the Fire & Life Safety Ecosystem™

Derek Vigstol, National Fire Protection Association Fall 2021 Industry Topics, Industry Topics

Electrical safety is often described as a three-legged stool encompassing proper installation, routine maintenance, and applicable safe work practices. It is this relationship that sets the stage for what can best be described as the electrical safety ecosystem as it lives within the larger overall NFPA Fire & Life Safety Ecosystem™. This Ecosystem is made up of eight key elements …

Successful Application of AI Techniques: A Hybrid Approach

Dr. Tony McGrail and Tom Rhodes Industry Topics, Summer 2021 Industry Topics

Artificial intelligence (AI) systems provide promise in analyzing and evaluating power system data. There is currently a large push  to use AI and machine learning (ML) to help reduce time performing maintenance on transformers and predict where and when the next transformer will fail.1,2,3 Major companies in various industries are promoting and telling the wonders of AI and ML: managing …

Electrical Wear in High-Voltage Circuit Breakers Using SF6 Alternative Gases

Nicola Garaboldi and Javier Mantilla Industry Topics, Summer 2021 Industry Topics

Every current interruption involves an arc burning between the contacts of a circuit breaker (CB). The produced arc energy and associated pressure increase is used in gas circuit breakers to cool the arc region leading to current interruption. The same arc energy causes wear that can be separated into two main phenomena: • Nozzle ablation, which affects pressure build up, …

Grounding System Testing: Simplified Fall-of-Potential and Step-and-Touch Voltage Testing

Logan Merrill Industry Topics, Summer 2021 Industry Topics

Verifying the functionality and integrity of a grounding system is critical to maintaining a safe workspace. Unfortunately, the tests used to achieve this goal, as well as the standards used to assess them, have required a specialized skillset, often leaving these tests done improperly or not at all. Now, with the industry progressing toward guided testing, new solutions make it …

Practical Non-Invasive Partial Discharge Cable Testing

William G. Higinbotham Industry Topics, Spring 2021 Industry Topics

Partial discharge (PD) is a poorly understood phenomenon that can cause catastrophic failure of electrical assets. It can exist at initial commissioning or occur only after decades of use. The dictionary defines partial discharge as: a flashover of part of the insulation system due to a localized electric field greater than the dielectric withstand capability of that part where the …

Motor Control Centers

Rodrick J. Van Wart Industry Topics, Spring 2021 Industry Topics

Most electrical equipment manufacturers provide life and performance expectancies with their equipment in the form of operation and maintenance manuals. Life expectancy is based on the premise that equipment has been professionally installed, is maintained in accordance with the manufacturer’s guidelines and recommendations, and is being used per the manufacturer’s designed intent. This premise is also noted in NFPA 70 …

Impact of SFRA Setup Issues on Transformer Frequency Response

Michael D. Wolf Industry Topics, Winter 2020 Industry Topics

Sweep frequency response analysis (SFRA) is a popular test to confirm the mechanical and electrical integrity of a transformer. However, the resulting traces can be difficult for field personnel to interpret due to the visual nature of the data. It is more straightforward to compare numbers against prior data or against a stated limit than to interpret subtle differences in …