Measurement of the Electric Field in the Vicinity of an Oil-Pressboard Interface Parallel to the FIELD

Electro-optical Kerr-effect measurements are performed to measure the spatial variations of the electric field in transformer oil in a parallel-plate electrode system with and without a pressboard interface bridging the gap between the electrodes. No space-charge field enhancements are observed at room temperature (25 °C) even with the interface present. At 125°C space-charge field enhancements are observed in transformer oil, but the field enhancement does not change upon the addition of an interface - the field near the interface was the same as the field away from the interface to within the ±5% precision of the experiment.