Turbine vibration , phase angle meaning

[Adam001]

we are measuring vibrations on steam turbine on bearing 1 and bearing 3 . we found that amplitude of bearing 1 is slightly changing but at a same phase angle which is 262 degree . Also the amplitude of bearing 2 is slightly changing but at same phase angle which is 162 degree . I understand that the two waves of two bearings are opposite in phase but my question is what is the phase angle 262 and 162 means in a simple sin wave curve or how it is measured or determined ? and what does is indicats ?

 

[Sofistioelevib]

Adam001,

when you talk about phase you are talking about delay from a reference.
The reference could be a trigger (key phasor for example) or another signal (ex sinevawe) and in second chase normally the delay is from the peak.

Taking the simplest way (kephasor or trigger) the phase is a delay from Peak of your signal respect of impulse of your trigger.

The delay espressed in ms is a time delay but respect to entire period of your sinusoid you can calculate the phase with:

periodtime:360degree=delayhase

Below a picture can help you to understand

 

[Adam001]

I can't open the picture can you send it to this mail ahanber@pgesco.com

 

[Shu Jiang PEng SE]

Phase angle means relative time gap between the peak amplitude of the measurements (reactions or displacements). In your case the bearing 1 get peak amplitude is approximately 1/3 period earlier than bearing 3 gets its peak reaction