Partial Discharge Characteristics of Automotive Engine Oil as Electrical Insulation Material Using HFCT Sensor and Loop Antenna

The development of alternative liquid insulation materials is crucial to improve the reliability and efficiency of electrical power distribution systems, particularly as substitutes for conventional transformer oil. This study investigates the partial discharge (PD) characteristics of automotive engine oil, specifically TMO 10W-40, to assess its viability as an electrical insulation material. A partial discharge test was conducted by applying variable high voltage between needle-plate electrodes submerged in oil, using both High-Frequency Current Transformer (HFCT) and loop antenna sensors connected to an oscilloscope for detection. The experiment involved multiple measurements under varying conditions, including Background Noise Off (BGN off), Background Noise On (BGN on), and Partial Discharge Inception Voltage (PDIV), with repeated trials for accuracy. The results showed consistent PDIV values with low standard deviation, indicating stable dielectric behavior. Notably, TMO 10W-40 exhibited initial discharge at a voltage of 2.02 kV across a 2 mm electrode gap, equivalent to an insulation strength of 1.01 kV/mm. These findings suggest that automotive engine oil demonstrates promising insulating properties and could serve as a potential alternative to conventional insulating oils under specific conditions.