A current transformer, includes, a Rogowski coil for detecting an alternating current of a main circuit, and outputting a measure of the alternating current as an analog-voltage signal, includes, a printed circuit board, a sensor unit and an optic transmission path. A control signal is adjusted to control a frequency of an oscillating signal from which the output signal is derived. A safety enclosure isolates the wall moving mechanism from contaminants and prevents exposure to the wall moving mechanism. An SMS communication session is enabled between the first user and the specific user based, at least in part, upon the one or more telephone numbers.