Abstract: At a security fence comprising a plurality of electrodes disposed in parallel, a transmitter applies an alternating voltage to at least one of the electrodes. Remaining electrodes are grounded as receive electrodes. An ammeter measures electrode current and a measured value corresponding to an operating capacitance of this electrode is acquired and provided in every electrode circuit. Disruption factors are compensated on the basis of these measured values by means of comparison to earlier measured values of the same or of the other electrodes and by means of comparison to specific measured value patterns. An alarm is triggered only given non-compensatable measured values.

Abstract: An electrode arrangement for capacitive guard fences wherein the conductor is horizontally stretched substantially parallel to the ground has a shape for preventing formation of water droplets which may collect as a result of precipitation from generating a false alarm and which also deters small animals from perching on the electrode. In one embodiment the electrode has a rectangular cross-section with the longest sides of the electrode being disposed substantially vertically. In another embodiment the electrode consists of two conductors having circular cross-sections which may be disposed parallel to one another or twisted. A further electrode embodiment has at least three conductors having very small circular cross-sections disposed at equal intervals from one another around a circular circumference. Means for facilitating water droplet runoff are provided at equal intervals which simultaneously serve as spacers for the conductors.