Item 17 - Arc Flash Analysis and Safety Program Development

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4. Scope of Services NFPA-70E requires an arc flash study to identify arc flash hazards, associated arc flash boundaries and required PPE. This regulation is to protect personnel by reducing exposure to major electrical hazards. The regulation helps companies and employees avoid workplace injuries and fatalities. A typical arc flash study requires accurate modeling of the power system and the components of the electrical distribution system including all the sources which may contribute to the fault locations. In order to accurately models the power system, detailed data gathering effort for induvial equipment is required for all the following components: o Power supplies which contribute to the fault including utility feed(s), generators (Standby or Co-Gens), UPSs and motors. o Protective device information including manufacturer, model, size and settings for low voltage breakers, high voltage breakers, fuses, disconnects and relays in order to determine the proper fault clearing times. o Power distribution equipment information including size, voltage ratings, current ratings, short circuit withstand capability, number of circuits, impedances and dimensions for switchgears, switchboards, panelboards, motor control centers, breaker/fuse/disconnect enclosures, automatic transfer switches, and transformers. o Feeder cable information including the size, type and distance. When accurate models is in place, multiple scenarios shall be created depending on the topology and operating conditions of the electrical network to calculate and determine the worst case incident energy on each individual equipment. This considers the alternative power sources which might have lower fault contribution, motors not operating, system energized by UPS or possible reduction of the fault contribution from the utility as well as bus ties and/or automatic transfer switches positions. It is also very important to obtain the decrement curve data for generators included in the study which accurately determines their fault contribution as well as obtaining the utility fault contribution from the utility company at the time of the study. 4.1.Data Gathering In order to prepare an accurate model for the power system study, a thorough data gathering effort shall be performed in the field for all the electrical equipment involved in the scope of the study. All the documentations, submittals, shop drawings, existing drawings such as AutoCAD, MicroStation, etc. shall be reviewed and the obtained data shall be incorporated into the models. While gathering the information in the field, the manufacture, model, size, ratings, and dimensions of the equipment shall be obtained in order to fulfill the arc flash