Using Simplified Models to Assist Fault Detection and Diagnosis in Large Hydrogenerators

Table 5

Upper journal bearing direct and cross-coupled stiffness, for several clearances conditions, with viscosity  Pas.

Clearance condition	Clearance condition	Coordinates	Bearing stiffness [GN/m]
		() [m]
A	Nominal clearance; (shaft eccentricity = 0 µm)		7.17	0.00	0.00	7.17
	Nominal clearance; (shaft eccentricity = 67 µm)		11.8	0.00	0.00	8.55
B	Measured speed-no-load		4.10	−0.71	−0.71	3.43
C	Simulated at nominal load		1.69	−0.18	−0.18	1.13
D	Measured at nominal load		2.55	−0.37	−0.37	1.15

The symbol “”indicates that the shaft position is different. In the clearance condition A the pad clearances are in the nominal values (200 µm) and the shaft is centered at coordinates (0,0). In clearance condition A* the pad clearances are once more in the nominal values but the shaft has an eccentricity of 67 µm.