Patent ID: 8129981

Claim:
An apparatus which can be coupled to at least two lines for transmitting a differential signal and/or for receiving a differential signal, wherein the differential signal is an alternating signal alternating substantially symmetrically about a predefined reference potential, the apparatus comprising: a balancing unit connectible to the at least two lines, said balancing unit having a center tap; and a monitoring unit having an input connected to said center tap, said monitoring unit being configured to monitor a center tap voltage between said center tap and the predefined reference potential and to detect a fault if the center tap voltage is greater than a predefined threshold value, said monitoring unit further including: a voltage divider electrically connected between said center tap and the predefined reference potential; a rectifier connected to said voltage divider; and a comparator having an input connected to said rectifier and an output, said comparator being configured to compare a divided-down and rectified center tap voltage with a reference voltage representing the predefined threshold value and to output an error signal indicating the fault.