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

Table 9

Estimated stiffnesses of the lower 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 ( vibrations)
		Gap [mm]	Shaft [µm]	Bearing [µm]	[GN/m]	Gap [mm]	Shaft [µm]	Bearing [µm]	[GN/m]
G6.65 (day 1)		1.889	85	4.1	0.11	1.716	85	22	0.57
	h	1.780	71	2.3	0.07	1.609	71	14	0.43
G4.25 (day 2)		2.037	68	9.6	0.31	1.867	74	59	1.78
	h	1.781	48	5.6	0.26	1.622	50	43	1.92
	h	1.763	44	7.3	0.37	1.616	46	41	1.98
	h	1.759	38	6.5	0.37	1.618	41	42	2.26
Balanced (day 3)		2.125	13	0.9	0.15	1.974	12	22	3.97
	h	1.829	12	0.6	0.11	1.679	13	20	3.56
	h	1.768	10	0.7	0.16	1.635	8.5	20	5.14