Arc flash assessment in a small hydropower plant

Abstract

The arc flash occurs by the sudden passage of current due to the unexpected breakdown of the dielectric barrier of ionized air across the energized poles. During this phenomenon, a large amount of energy is released in the form of heat and personnel directly exposed to this event are subject to third degree burns, blindness, shock, hearing loss and even death. The objective of this paper is to show a practical methodology for calculating incident energy at work distance and the external boundary of an arc flash in a medium voltage room with cells operating at a voltage level of 34.5 kV. IEEE 1584.1-2022, IEEE 1584 -2018, IEC 60947 and IEC62271 standards do not cover arc flash calculations for voltages higher than 15kV, therefore, to achieve the stated objective, we will use Ralph Lee's method and then use software to verify the obtained results. We will also present the calculation by applying the electromagnetic field method.  Analyzing the results, we concluded that for our case study it is required that all personnel who enter to perform works with the switchgear in operation must have category 4 personal protective equipment according to NFPA 70- 2018 for incident energy range between 25 and 40 cal/cm². In Panama there are many facilities with operating voltages above 15 kV, therefore, it is necessary to conduct further research and calculations in these places to ensure the safety of workers against the arc flash potential risk.