EFFECT OF TEMPERATURE VARIATIONS ON WAVE PROPAGATION CHARACTERISTICS IN POWER CABLES

Partial discharge (PD) mapping and fault location in power cables are techniques based on the principle of time domain reflectometry (TDR), a phenomenon that in turn depends on the high frequency wave propagation characteristics of the power cable. Furthermore, power cables are increasingly being used to simultaneously convey electric energy as well as communication signals in technologies such as smart grids. In operation, power cables experience wide ranging temperature variations due to changes in the load current flowing through the cable. It is therefore necessary to understand the effect of temperature variations on the high frequency characteristics of power cables. Simulations and experimental tests performed in this study show that temperature variations introduce errors in TDR measurements. It is also shown that when temperature in the cable changes from 22 degrees C to 58 degrees C, attenuation increases by one order of magnitude while the propagation velocity increases by an average of 4 %. The phase constant however decreases by an average of one order of magnitude. The implications of the findings are that temperature effects have to be taken into account when designing communication channels in power cables.