Experimental Estimation of Journal Bearing Stiffness for Damage Detection in Large Hydrogenerators

Table 8

Estimated stiffnesses of the upper journal bearing of a LHG, using vibration signals measured during the three-day balancing process of the generator rotor.

Unbalance ISO grade	Relative time	Transducer -direction (1 × vibrations)				Transducer -direction (1 × vibrations)
		Gap [mm]	Shaft [µm]	Bearing [µm]	[GN/m]	Gap [mm]	Shaft [µm]	Bearing [µm]	[GN/m]
G6.65 (day 1)		2.124	55	20	0.44	2.013	62	()	—
		2.073	40	14	0.42	1.956	43	()	—
G4.25 (day 2)		2.190	89	28	0.37	2.064	99	()	—
		2.071	48	19	0.47	1.967	57	()	—
		2.037	42	17	0.49	1.937	51	()	—
		2.011	40	24	0.69	1.919	51	()	—
Balanced (day 3)		2.156	23	3.4	0.18	2.049	28	()	—
		2.057	12	1.9	0.19	1.957	18	()	—
		1.995	10	2.1	0.26	1.903	13	()	—

The measured vibrations are not reliable.