Self electrical breakdown in biodegradable oil

The fundamental breakdown physics of biodegradable oil is investigated with high-speed electrical and optical diagnostics with temporal resolution down to several 100 ps. The set up employs a cable discharge into a coaxial system with axial discharge and load line to simulate matched terminating impedance. A unique feed-through design creates no discontinuities in the system lines through the discharge chamber. The impedance of the system is matched at 50 ohms including a novel design for impedance matching transitions from discharge cable to coaxial system to load line allowing for a sub-nanosecond response. This paper presents results on self-breakdown with voltages of up to 60 kV. Self-breakdown is achieved by charging the discharge cable and load line to +/-30 kV respectively. Transmission line type current sensors and a capacitive voltage divider with fast amplifiers/attenuators are used in order to obtain a complete range of information from amplitudes of 0.1 mA to 1 kA with temporal resolutions of 300 ps. Optical measurements include high speed photography and shadowgraphy. Detailed optical diagnostics along with high-speed electrical diagnostics will address the mechanism initiating/assisting biodegradable oil volume breakdown.