Smart grids yield in an efficient energy distribution, driven by advanced grid management and diverse technologies' integration. For instance, the remote monitoring of transmission lines, facilitates the development process of conventional electrical networks into smart grids. One form of such remote monitoring applications can be actuated by means of a drone, which carries an embedded intelligent sensor. These drone-based applications referred to as Unmanned Aerial Systems (UAS), thus allow an instantaneous surveillance of the actual status of transmission lines, remotely. Accordingly, this paper presents an experimental setup of an "all-optical" electrical sensor, confronted with different forced voltage/current (V/I) levels, in order to test its feasibility for future applications in drone-controlled, electric grid monitoring processes. After analyzing different measurements' outputs, and comparing them with reference values outputted by reference V/I sensors, the resulting deviated errors are tabulated and justified. Furthermore, the exploration of the studied sensor's pros and cons, and by taking into consideration the space/weight restrictions that a drone-based application obtrudes, related future work is suggested.