Technique for Reducing Transient Voltages in Multiconductor-Shielded Cables

It is a common practice that the unused pairs (inactive conductors) in shielded cables are left open (open circuited at the terminal block) in telecommunication systems. In this paper, it is shown by both theory (based on transmission line analysis) and experiments that if those inactive conductors are shorted to the cable shield, then the transient voltages on the other active conductors (conductors in service) can be reduced when external transients/faults due to lightning or switching couple to the shield. This could be a good EMC practice for transient voltage reduction in telecommunication systems.