WE have a vibration problem with a Solar Centuar driven Alternator . Alternator RPM is 1800 CPM. For last couple of months the reading is going up from 0.09 IPS and now reached to 0.38 IPS. The new peak generated is 2nd harmonic of alternator and this is the culprit. Now apart from a coupling problem what else can contribute to this. There is an excitor after the NDE bearing of alternator.I am getting more Vib. on NDE bearing horizontal direction. DE also shows increment. What are the electrical faults expected? Thax for your thoughts

I can think of nothing but 2LF at 60 HZ (1800*2/60)

We found that the coupling is damaged .See some pic.
Thanx