Electrified fence using HT source - is typically for protecting radio transmitter and uses alarm relay responsive to breakage or earthing of electrified network

摘要

The fence has an alarm (2) operated if the electrified network (7) is broken or earthed. The alarm has a relay coupled between a terminal of the electrified network (7) and the earth connection for the HT source (1) coupled to the latter. The relay contact moves from the working position to the rest position when the electrified network (7) is broken or earthed, e.g. by a person attempting to cross the fence. Pref. lightning protection is provided by a respective element or fuse (31,32) connected between one of the network terminals and the terminal of the HT source (1) which is not connected to earth, or to the alarm circuit (2). The lightning protection also uses a Zener diode (5) in parallel across the control inputs of the alarm circuit (2).