This article is related to arc flash study for system with multiple sources. Multiple sources happened when protective devices tripping time varies or not open at the same time resulting in subsequent removal of short circuit sources. If the worker cannot get away from the arc flash source, then the total incident energy is sums up until ultimately cleared by the last protective device. However, of course this is just a conservative assumption since arc fault can be self-extinguished during the transition state or if the available bolted fault current was already small to sustain the arc fault.

Most grid connected renewable power plant are equipped with inverter for AC interfacing. Inverter like any other electrical component such as the transformer have also provided with unit protection. Protection like the anti-islanding is used to turn-off the inverter operation in predetermine time after the system has been disconnected from the main grid to avoid unwanted event. Typically, a time delay of 1 second is used to support transient stability however it can be increased/decreased further as may deemed necessary.

BESS, Solar, and Wind Turbine Generator (WTG) can be assumed to have multiple sources especially when they are connected to the main grid as can be depicted in Figure 1. Without inter-trip communication link, subsequent operation of protective devices is possible which could result in varying arc fault level. I made an analysis for this case and would appreciate any comments/recommendations from your end.

Ta! MJ

This is the sample analysis I have made. Feel free to provide comments or recommendations.