The Voltage and Current Characteristics of Breakdown in Transformer Oil under Impulse Voltage

Summary

This paper presents an experimental investigation on transformer oil dynamic breakdown characteristics when subjected to impulse voltage. The dynamic characteristics of the discharge were explored by examining the instantaneous variations of current and voltage at the instant of breakdown. A dedicated test cell was constructed to contain the insulating oil. A sphere-sphere electrodes gap of variable length was used for the experiments. Series of tests have been conducted through a non-inductive resistor of 50?, connected in series with the test cell for three different inter-electrodes gaps; 1mm, 2.5 mm and 5mm. Other Series of test have been conducted for 1mm inter-electrodes gap, without the use of non-inductive resistor, and through different non-inductive resistors: 50?, 4.8 k? and 9.6 k? connected in series with the test cell. The results revealed that the current and voltage wave shapes at the instant of breakdown showed similar variation for all gap lengths. However, the use of non-inductive resistors in series with the test cell reduces the time taken by the breakdown and has a significant influence on the stage where the breakdown occurs.

Additional informations

Authors

Qin , Cheng , Zhang Chaohai, Zeng