Report on High Energy Arcing Fault Experiments - International Experimental Results from Bus Duct and Switchgear Enclosures

Published

July 1, 2024

Author(s)

Gabriel Taylor, Anthony D. Putorti Jr., Scott Bareham, Christopher U. Brown, Wai Cheong Tam, Michael Heck, Lucy Fox, Stephen Fink, Michael Selepak, Edward Hnetkovsky, Nicholas Melly, Kenneth Hamburger, Kenneth Miller

Abstract

This report documents an experimental program designed to collect data and information to evaluate the performance of models developed to estimate the electrical high energy arcing fault (HEAF) hazard. This report covers full-scale laboratory experiments using representative nuclear power plant (NPP) three-phase electrical equipment. Equipment included medium-voltage metal-enclosed bus ducts and switchgear and low-voltage metal-enclosed switchgear. Electrical, thermal, and pressure data were recorded for each experiment and documented in this report. The experiments include five medium-voltage switchgear, two medium-voltage non-segregated bus ducts, and three low-voltage switchgear. These experiments differed from past programs in that the effects to adjacent and nearby equipment were also evaluated. The data collected supports characterization of the HEAF hazard, and these results will be used to complement the data used for HEAF hazard modeling tools and support potential improvements in fire probabilistic risk assessment (PRA) methods. The experiments were performed at KEMA Labs in Chalfont, Pennsylvania. The experimental design, setup, and execution were performed by staff from the NRC, the National Institute of Standards and Technology (NIST), Sandia National Laboratories (SNL) and KEMA Labs. These experiments were sponsored by member countries of the HEAF 2 international agreement under the auspices of the Organisation for Economic Co-operation and Development (OECD). The HEAF experiments were performed between August 7 and 18, 2023. These experiments used nominal system voltages of either 0.6 kV (AC), 4.16 kV (AC) or 6.9 kV (AC). Actual arc durations of the experiments ranged from approximately 0.5 s to 8 s with fault current targets ranging from approximately 8 kA to 30 kA. Real-time electrical operating conditions, including voltage, current, and frequency, were measured during the experiments. Heat fluxes and incident energies were measured with plate thermometers and slug calorimeters at various locations around the electrical enclosures. Internal enclosure temperatures were measured using a fiberoptic system. The experiments were documented with normal and high-speed videography, infrared imaging, and photography. Insights from the experimental series include timing information related to enclosure breach, event progression, mass loss measurements for electrodes and enclosures, peak pressure rise, along with visual and thermal imaging data to better understand and characterize the hazard. These results will be used evaluate the adequacy of existing HEAF hazard modeling tools and for potential improvements to fire PRA methods related to HEAF.

Citation

Technical Note (NIST TN) - 2290

Report Number

2290

NIST Pub Series

Technical Note (NIST TN)

Pub Type

NIST Pubs

Download Paper

https://doi.org/10.6028/NIST.TN.2290

Local Download

Keywords

High Energy Arcing Fault, Arc Flash, Electrical Enclosure, Switchgear, Bus Duct, Electric Arc, Fire Probabilistic Risk Analysis, Fire Probabilistic Safety Analysis

Citation

Taylor, G. , Putorti Jr., A. , Bareham, S. , Brown, C. , Tam, W. , Heck, M. , Fox, L. , Fink, S. , Selepak, M. , Hnetkovsky, E. , Melly, N. , Hamburger, K. and Miller, K. (2024), Report on High Energy Arcing Fault Experiments - International Experimental Results from Bus Duct and Switchgear Enclosures, Technical Note (NIST TN), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://doi.org/10.6028/NIST.TN.2290, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=957223 (Accessed March 13, 2025)