Arc Flash Light Intensity Measurement System Design

Electrical arcs emit extremely high intensity light across a wide spectrum that can damage the eye´s delicate structures, such as the cornea or the retina. Developing industry safety standards to mitigate light hazards is a critical component of arc flash safety. Accurate measurement of light intensity is the first step in understanding the level of eye protection needed. Traditionally, light measurement devices are an assembly of light-detecting resistors made from cadmium sulfide (CdS) or silicon (Si) cells. However, their response times are inadequate for capturing the peak light intensity or the dynamic changes during the initial arc flash. In addition, the brightness of an arc flash is greater than the measurable light levels from traditional light measurement devices. Furthermore, the light sensitivity of traditional sensors does not match the Commission Internationale de l´Éclairage luminosity function V(λ) curve, which defines the human eye´s sensitivity to bright light as a function of wavelength under typical ambient light conditions. This paper discusses a novel light measurement technique to overcome the limitations of traditional approaches. This design is capable of measuring the light intensity of the arc flash as perceived by the human eyes. These results can be used to evaluate the potential of an arc flash to harm the eyes.