Investigation of Partial Discharge Activity of a Conducting Particle in Nanofluid under Composite Voltages

In the present work, an attempt has been made to obtain stable nanofluids by dispersing an appropriate amount of titania nanoparticles in transformer oil as base oil. The surfactant added in appropriate amount helps in achieving consistent dispersion of the nanoparticles in colloidal solution. A set of experiments were done for understanding the discharge trait because of particle movement in nanofluid and pure transformer oil. It is noted that the particle levitation voltage in nanofluids achieves an increment as compared to base transformer oil. It is realised that partial discharges are generated because of movement of particle in nanofluid which emits UHF signals with 0.9 GHz as major frequency content. The partial discharge trait in nanofluid is studied under AC, DC and composite voltages. The acquired UHF signals are fed to spectrum analyser to realise number of discharges that occurs on application of supply voltage. The number of discharges are noted to be lesser in nanofluids compared to transformer oil. For investigating the phase of supply where discharges are generated because of particle movement, Phase Resolved Partial Discharge (PRPD) studies were done for the motion of conducting particle in nanofluid on application of AC and composite voltages.