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 3

Breakdown results of pure oil and different types of nanofluids under negative 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	23.70	0.63	23.70	0.63	23.70	0.63
5	21.71	0.69	22.04	0.68	20.02	0.74
10	19.98	0.75	21.05	0.71	18.26	0.82
20	18.86	0.80	19.61	0.76	17.11	0.87
40	16.70	0.90	18.03	0.83	15.80	0.95