Reference Measurement System for Traceability of Composite and Combined Waves

Type and routine testing of new HV cables and switching elements are conducted using composite and combined waves. In this testing the fundamental voltage stress, HVDC or HVAC, is superimposed with a Switching or Lightning Impulses (SI, or LI). Lacking traceability for direct measurements of these wave shapes separate measurements are followed by calculation of the actual voltage stress on the device under test, which is described in the current IEC 60060-1 standard. Commercial universal measurement systems exist on the market, but until now such measuring systems lack traceability.

A measurement system has been developed by RISE which will provide traceability for composite and combined waves, consisting of a software and two modular universal RCR dividers. The software for sampling and analysis, acquires a composite wave for two terminal test objects, or measures and calculates the combined wave stress from two composite waves for three-terminal tests. The extended measurement uncertainties for the wave components are 200 and 400 μV/V for DC and AC and 1% for peak voltage of SI and LI. The resulting system measurement uncertainty for composite and combined waves will be presented, and new parameters discussed for input to the revision of the IEC 60060 series.