May we perform ODS with single channel analyzer using a tachometer for phase reference? If yes, how much accurate it will be?

The answer is yes if the vibration frequency is 1xSS. The accuracy is good if the vibration levels are steady over time. The ODS test using two channel analyzer is more accurate, since the amplitude values are a ratio referenced to one location.

Walt

Can we go for 2x ODS by putting two reflector tapes or 3X ODS by putting 3 reflector tapes on the rotor? Is only 1X ODS possible through single channel analyzer? If at other frequencies it is possible by single channel analyser, how?

Akhtar,
Two or three markers would "trick" the analyzer for getting a 2xSS or 3xSS frequency, but the phase reference to the shaft position would be lost. My opinion is that you cannot do ODS test at any frequency except 1xSS with single channel analyzer. I welcome an explanation if this is incorrect.

Walt

You should be able to get synchronous harmonics (2X, 3X, etc.) amplitude and phase with a single channel analyzer using a tachometer input. I'm assuming that the single channel analyzer has the tracking filters for the higher order measurements. You would only need a single piece of tape on the shaft.

CSI equipment will allow you to monitor the phase of different orders of turning speed with a single piece of photo cell tape in the monitor peak verses phase function. It allows you to input the order of turning speed you are interested in.

IRD's E-shape also allows you to tell it how many shapes you want to display. It takes a while to get all the data.

Dave

This is specific to CSI, but you can use the Model 444C Strobe instead of the photo tach to set the frequency you want to compare. This way you don't have to stop the machine to put reflective tape on.
Using the Strobe allows you to set the frequency to other than harmonics of 1xSS.