Methods of determining safety boundary and PPE by analysing arc-flash incident energy in medium voltage panels

Abstract

Arc-flash events still occur frequently in industries especially in Indonesia and there are many operators and technicians have got burn injuries caused by it. To avoid this accident, this paper discus about arc flash and its incident energy as well as personal protective equipment (PPE) should be worn by those working with electric panels (switchgears). To demonstrate how incident energy is calculated and the protection boundaries are determined, a 6 kV, 3750 kVA utility panel in a geothermal power plant (60 MW) is used as object. The steps have to be done in this research are bolted fault current and arc fault current calculations, calculation of incident energy and determining both protection boundaries and the relevant PPE. As result, it is found that with protection setting clearing time of 0,12, the incident energy is 4,418 J/cm2 and the protection boundary is 1.4 m. The danger will increase with longer clearing time of relay or closer distance to the panel. This paper will hopefully be very help full for the responsible engineers to analyse the danger of any kind of panels and to determine PPE for workers.