PROJECT TITLE :

Aging degree evaluation for paper-oil insulation using the recovery voltage method

ABSTRACT:

The paper presents new diagnostic method applied to assess aging degree for paper-oil insulation used in skilled electrical power device, primarily including medium and high power transformers. The described method is based on modified diagnostics using the recovery voltage impact occurring in dielectrics (RVM ??? Recovery Voltage Ways). Modification of the RVM technique applied thus so much, which is currently used only to assess moistening degree for paper-oil insulation in power transformers, consists in a new parametric analysis of recovery voltage time characteristics. Simulation and experimental tests applied in laboratory conditions for adequately prepared insulation samples have proven that the time-constant of recovery voltage decay (??R_MIN) is the most prone parameter as regards quantitative modification in the function of aging of the examined insulation. This conclusion is additionally confirmed by statistical studies, in which a multi-parameter variance analysis methodology has been applied. An original equivalent circuit diagram of the insulation has been used to simulate aging degree of paper-oil insulation samples in numerical tests. The diagram relies on the Cole-Cole kind dielectric response model.