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Tenaska Inc. Power Generating Stations - NFPA 70E Arc-Flash Hazard Analysis
Columbus, Ohio

Tenaska Inc. Power Generating Stations - Arc-Flash Hazard Analysis Client: Tenaska

Hull performed NFPA 70E arc-flash Hazard Assessments for multiple gas fired peaking power plants across the country ranging 200 MW to 800MW in size. Currently the project is ongoing.

The purpose of this study was to calculate the amount of energy available in case of an arc flash fault and recommend a sufficient level of personal protective equipment (PPE) while working on energized electrical equipment. Between100-200 pieces of equipment have been identified as potential equipment that energized work would be performed on depending on the facility. Hull calculated arc-flash energies, provided appropriate Personal Protective Equipment (PPE), developed Energized Electrical Work Permits (EEWP's), and labels for this equipment. When the initial report was prepared it was determined that certain equipment fusing was Inadequate and other protective device settings could be adjusted to reduce the hazard levels of specific equipment.

The arc-flash study results were provided in a format to become an integral part of the Tenaska's electrical safety program including all assumptions, recommendations, EEWP's, and PPE determinations. As always it was emphasized that the safest way to work on equipment is while it is de-energized.

This analysis was based on one line diagrams provided of each facility and supporting data. Also, information collected during a preliminary site visit with follow up collection provided by each facility with the support and direction from Hull. Specifically, data gathered and used to calculate the potential arc-flash hazards included equipment locations, wire size and type, raceway size and type, distance from source to load, bus sizes, switchgear, MCC, panelboard arrangements, and utility source information. Utility short circuit information was obtained from the local utilities and in all cases included multiple suppliers.

Hull utilized the EasyPower® Arc-FlashTM software system for this project. EasyPower is a comprehensive arc-flash program that provides the latest in NFPA70E, and IEEE1584-2002 calculation algorithms to calculate the arc-flash boundaries, incident energy, and personal protective equipment requirements (PPE) necessary for personnel safety and NFPA70E compliance. As a value-added service, we will also provided the following documentation, in spreadsheet format, for safety program compliance within NFPA70E guidelines including:

• Incident energies at each equipment, protective device, bus, and feeder;
• Incident energies at user-defined working distances; and
• Required protective flame resistant clothing class for arc flash areas.

Hull prepared a summary report for each facility detailing the findings of the analysis and identifying areas of extreme danger, recommendations on how to proceed, EEWP's, Labels, and PPE requirements.

Finally, label installation and training of qualified and unqualified workers was/will be performed at each facility allowing the facility to be in full compliance with NFPA 70E, NESC-2007, and IEEE-1584

To find out how Hull can help, please contact Hull's Electrical Engineering Division Leader, Andrew Holtom, PE at (614) 793-8777.