Experimental Evaluation of Detection Speed in Optical-Based Internal Arc Fault Control Devices Under Variable Illuminance Conditions

Optical-based internal arc fault control devices (IACDs) play a crucial role in the speed of detection of arc faults in low-voltage switchgear assemblies. They can utilize different types of sensors (point and line) and contain different types of output (semiconductor and relay). The configuration of an IACD will influence the total detection time of such a system. This article presents a screening methodology of comparing the detection speed of commercially available optical-based IACDs. It describes the method used to measure the speed of operation of IACDs using variable illuminance conditions generated by a commercial photographic flash unit. The results are presented and compared using box plots and individuals–moving range (I-MR) charts. Box plots offer at glance comparison of influence of different test conditions on the speed of operation, and I-MR charts are used to visually assess the measurement points. The measurements also indicate a dependence of the reaction times of the tested IACD on the energy of the flash. This information is useful in designing the proper placement of optical sensors and allows the selection of a system configuration that will ensure the fastest reaction time under given test conditions applicable to low-voltage switchgear assemblies.