Observation of Prebreakdown Phenomena and Measurement of Dielectric Constant under Microwave Transformer Oils Frequencies in the Mixture of PCB and PXE

Authors: Mehmet Oğuz HENGİRMEN, Arif NACAROĞLU

Abstract: The electrical properties such as discharge development under a high voltage impulse having -40 kV crest value and dielectric constant under microwave frequency have been investigated for commercial transformer oil polychlorinated biphenly (PCB) and its mixtures with phenyl-xylene ethane (PXE). The prebreakdown phenomena has been observed by the fast photographing shadowgraph technique. The oneshot photographs have been taken for multiples of 5 nanoseconds delay time. Blumlein Cable Generator is designed and used to create a signal with very short rise time. A point cathode-plane anode system is used to observe the prebreakdown under -40 kV of impulse excitation. The gap distance is taken as 2 mm. and pulse duration as 188 nanoseconds. The dielectric constant of the mixture is experimentally measured between 8.5 GHz and 10 GHz frequencies.