Mitigation method First, the metallic foil of the 10-pair copper cable was connected to the main earthing terminal at the customer site. As a result, the transient voltages were reduced to 1/6 of the value that had before mitigation (Figure 1.5-6). The remaining voltage, which was about 23 Vp-p, still caused some clicking noise. To solve this problem, it was decided to install a neutralizing transformer at the distribution point. This led to a decrease of about 3 Vp-p, making the disturbance vanish. The buried power supply cable of the fence was poorly isolated, i.e., the connecting points were not isolated. Because of the disturbances, the following solution was found, in agreement with the owner of the electric fence: increase the distance between the power supply cable of the electric fence and the optical fibre cable, and properly isolate the connectors. 230 V a.c. Electric fence Optical fibre Noise a b a' b' Miti(08)_F1.5-5 Neutralizing transformer Figure 1.5-5 – Mitigation method 1 0.5 ms 20.0 V A:M1 0.5 ms 20.0 V A 1 Miti(08)_F1.5-6 pkpk (1) 22.5 V Figure 1.5-6 – Mitigation results – 3 – Case study 1.5