Effect of cable load impedance on coupling schemes for MV power line communication

In this work coupling of communication frequencies within the CENELEC A-band to medium voltage cables is studied. Inductive and capacitive signal coupling is considered not only on basis of technical performance, but also on basis of practical aspects as installation. The effectiveness of coupling schemes depends on the impedances of installed equipment at the cable terminals. The frequency response of a 10 kV, 400 kVA cast resin distribution transformer is investigated. In the frequency range of interest, the behaviour is best described as a capacitance of typically 1 nF. The signal transfer over a 4 km paper cable terminated by various load impedances to mimic real equipment is studied. From the results it is concluded that for inductive coupling performance can be low within the CENELEC A-band, but can become competitive if frequencies up to 1 MHz are allowed. Further, the location of signal coupling has a strong effect on the noise spectrum.