Statistical problems at evaluation of breakdown voltage in hybrid solid- gas- insulation
HALLER, R., MARTÍNEK, P., MÜLLEROVÁ, E. Statistical problems at evaluation of breakdown voltage in hybrid solid- gas- insulation. Portorož, Slovenija, 2013.
|Anglický název:||Statistical problems at evaluation of breakdown voltage in hybrid solid- gas- insulation|
|Autoři:||Prof. Ing. Rainer Haller Dr. , Ing. Petr Martínek Ph.D. , Doc. Ing. Eva Müllerová Ph.D.|
|Abstrakt EN:||For a reliable design of the electrical insulation the knowledge of withstand values against electrical breakdown is required. With respect to the stochastical character of the electrical breakdown for withstand values are commonly used values having a very low breakdown probability (i.e. 10%- or 1%- quantils). For their evaluation different statistical procedures and methods are introduced and standardized, but a general requirement for using that is the statistical independence of the measured values. At test objects with insulation of non self- regeneration type as solid-, liquid- and even gaseous insulation in closed volumes there are some difficulties to fulfil these conditions. For studying these effects at a hybrid solid- gaseous insulation some investigations at AC- and LI- test voltage were performed. As test object was used a closed vessel filled with N2- O2- gas, particular with a polymeric barrier positioned in the middle of the electrode distance, measured at different values of distances, pressure and field configuration. At AC- voltage no problems with statistical independence of breakdown values were obtained. This was valid both at pure gas- and at barrier- gas - insulation, the introduced method for determination of low quantils could be used. It was investigated, that in the case of low inhomogeneous field the breakdown probability could be approximated by an additive- mixed distribution, dependent on the type of breakdown process. In opposition to that it was found, that at LI-voltage in some cases the measured values are not statistical independent and, therefore, the determination of the withstand value of breakdown voltage is problematically. These problems are discussed and a pragmatic procedure for obtaining the 10%- quantil is supposed however, for a better interpretation and understanding of that further investigation seems to be necessary.|