Shifting of phase angle

At one of the power station, during insitu balancing, after putting trial weight, the phase angle in the horizontal direction moved into clockwise direction and the phase angle in the vertical direction moved into anticlockwise direction. We want to know the following:-
1. Whether it can be said that balancing will not help in above case.
2. What will be the reason for such behaviour


Kindly give your valuable feedback.

(steam turbine)

 

[GregLocock]

Hmm, nasty. I assume you've double checked you readings? Have you tried putting balance masses on at all four quadrants? If you don't get nice even circles from that exercise then you have a non-linear system (or poor measurement technique). I often see this sort of problem on automotive drivelines, because we have a lot of radial slop in one bearing. Cheers

Greg Locock

 

[grahamchevis]

I have seen phases change on fans when the problem was looseness on unbalance. I once tried to balance a fan with a high 1x vibration and the problem turned out to be the bearings on one end loose on the shaft.