Investigations of Particle-Initiated Insulation Breakdowns in Bearings

Table 1

Particle type, concentration and size classes added to lubricant to form different test lubricant sample A1–A4.

	Sample A1	Sample A2	Sample A3	Sample A4
Particle type	Arizona test dust	Carbon black	Aluminium	Iron
Particle concentration (mg/L)	150, 75, 30, 15, 7.5	150, 75, 30, 15, 7.5	150	150
Particle size class	5.5–100 μm	8–10 μm	160 μm	Fine dust
Dry particle in microscope