Preparation of Three Types of Transformer Oil-Based Nanofluids and Comparative Study on the Effect of Nanoparticle Concentrations on Insulating Property of Transformer Oil

Table 2

Breakdown results of pure oil and different types of nanofluids under positive lightening impulse voltage.

Nanoparticles concentration (%w/v)	Fe3O4		TiO2		Al2O3
	Time to breakdown (µs)	Average streamer velocity (km/s)	Time to breakdown (µs)	Average streamer velocity (km/s)	Time to breakdown (µs)	Average streamer velocity (km/s)
0	13.03	1.91	13.03	1.91	13.03	1.91
5	14.12	1.77	13.94	1.79	14.23	1.75
10	14.63	1.70	14.06	1.77	14.77	1.69
20	13.67	1.82	13.07	1.91	15.62	1.60
40	13.20	1.89	12.90	1.93	14.51	1.72