Abstract:
High voltage cables are used worldwide to transmit
electric power in special cases such as underground and
underwater, where the overhead lines can’t be used. Polymeric
cable insulation is most commonly used for high voltage
applications due to its several advantages like maintenance free
when compared to oil impregnated paper. As well known,
insulation is the very important concern in high voltage system.
Once insulation breakdown occurs, the entire electrical system
may get collapsed. So, it is necessary to understand the
behaviour of insulation under different stress conditions.
Several research papers explained about insulation failure that
occurs due to electrical and thermal stress. But in actual
practice, the high voltage cable is subjected to both electrical
and thermal stress simultaneously. So, the authors have
performed a series of experiments by applying both thermal
and electrical stress simultaneously in power cable. The various
thermal stresses are created in power cable by injecting
different load current and conducted breakdown test at the
controlled outer temperature of 30 °C. The different
temperatures that are produced by load currents in the
insulation are analyzed. These test methods are used to
investigate the dependency of breakdown voltage under
different thermal conditions. The distributions of breakdown
voltages under different stress were studied by using Weibull
distribution.
