looking for some advice regarding an overhung fan that has been having an ongoing vibration issue since installation. 200kw motor 1480rpm. Fan runs with acceptable vibration levels at 70% but get worse at we get close to 90% before dropping down slightly at 100%. Initially i would have thought a resonance issue but i would like to know if this is a Air flow/turbulence issue and what thing to expect. I've added a word document with relevant data if anyone wishes to have a look.