The protection of the electrical plant, equipment and components in aerospace applications represents a hot research topic. In the last years, great efforts have been focused on the parallel arc-fault detection. As well known, in many cases the conventional thermal magnetic breakers does not offer adequate protection against arc fault, despite their effects can be as serious as those produced by a short-circuit. Arc-fault detection requires recognizing the arc signature contained in the current waveform. For this reason, an inescapable choice to face this problem is to adopt proper digital signal processing techniques. In a previous work, the authors have proposed a technique based on the estimation of the energy which may be related to the arcing activity. It has been tested by using a high accuracy current measurement system, and it has been shown that it ensures remarkable performance beside the simplicity of the algorithm. In this paper the aspects related to the practical implementation of the proposed method have been faced. Particular care has been paid in evaluating the impact of the measurements uncertainties on the reliability of the method. This analysis has led to the development of a low cost prototype of parallel arc fault detector, which uses less sophisticated hardware and can be employed in AFCBs (Arc Fault Circuit Breakers). A deep experimental activity has been carried out in our laboratory. It has been shown that the simplified algorithm and the worse measurement accuracy of the prototype have a negligible effect on the effectiveness of the parallel arc fault detection.