Our machine Siemens SGT 700, dual shaft machine, total 4 bearings, compressor bearing no-1 having 2x vibration measurement along with normal vibration measurement. Same probe used for both measurement. My doubt is why 2x vibration is necessary? And why it is measured in bearing no-1 only?
Generally angular misalignment of shaft causes vibration to occur at 1x of speed frequency, and parallel misalignment of shaft causes vibration to occur at 2x of speed frequency. Since vibrations occurring are an impact of both angular and radial misalignment or either of them, so both 1x and 2x amplitudes are utilized to get proper understanding of the condition of the machine.
2x amplitudes are more minute than 1x amplitudes and bearing no.1 must be taking a higher burnt.