Comparing the results of increasing-voltage design and qualification life tests on HVDC and HVAC cables: the effect of voltage-step growth rate and insulation thickness factors

Design and qualification tests of HVAC and HVDC cables include accelerated life testing on models that can have different length and insulation thickness. Breakdown strength, voltage breakdown and accelerated life tests could be performed using different rising voltage procedures, from continuous ramp to step tests, with rise rate, step width and length of various extent. Comparing then the experimental data is not straightforward. This paper has the aim of deriving expressions which can be used to achieve homogeneous test data sets, including dielectric strength values and life times, from test procedures and models which may differ for voltage rise rate, initial step voltage, step length and width, as well as cable length and thickness. The fitting of the proposed model to experimental data is made referring to test objects consisting of polymeric cable models for HVDC applications.