Hey guys,I'm a newbie to this so please take it easy on me.
My section has recently purchased a CSI 2130 and I would like to perform cross channel phase to distinguish unbalance from misalignment, however I am unsure as to the procedure for this.A procedure we have got hold of indicates that channel A remains static (say motor non drive end) and channel B is placed at specific points on the drive train and readings taken relative to channel A, but this disagrees with other info I have. What is correct?
Does anyone have a simplified procedure for this?Also, what happens when a negative reading is obtained? eg -22 deg.
Thanx

This message has been edited. Last edited by: David_F,

Hi David_F,
You can get cross channel phase, by placing one ch(A) as reference and place the other ch(B)at another location. The reading normally is taken from ch-B relative to ch-A. It means, if you have 20 deg Angle, ch-B peak leading 20 deg from ch-A, or if you look from ch-A to ch-B this will be -20 deg. So, +/- sign indicate leading or lagging of your peak to the reference peak.

However, for your purpose, I do not think the sign is important. It will be enough to get absolute phase difference. For indication of coupling missalignment, you should put at the same direction across the coupling (example MIA and PIA), unless you mean bearing housing missalignment between DE and NDE. Therefore when you put ch-B sensor at other location&direction, you might need to also change the location&direction of ch-A.

By moving around ch-B, my guess is that you want to know how other point move relative to ch-A, maybe to construct ODS? I don't think this necessary.

david,
Arief is basically correct. I've attached a copy of a phase/amp. data sheet taken from TA's level II manual that I use to record phase and amplitude data for future reference. I use Ch-a as my stationary point and Ch-b as my "rover". Just record the data on the sheet and your home free. Be aware that you have to be careful with transducer direction. For instance say you are taking axial readings on a motor and pump, most of the time your transducer will not be pointing in the same direction but 180 deg opposite of each other (pump <-- --> motor) You have to compensate for the 180 difference. I normally put an arrow on the line from the circle to the equipment showing transducer direction. O->- or O-<-. hope this makes sense.
Kind regards

In addition to a bubble diagram like Roy's, I use these sheets from Universal Technologies.

Interpreting_Phase.zip (31 Kb, 132 downloads)

David,
Since you are using CSI equipment, there is another option available. I use a 2120-2 and the Advanced Two Channel Analyzer so I can store these readings for future use (data can be downloaded into the AMS database via Vibpro.
When you store the information from the accelerometer, you indicate the relationship to the other readings using a "-" sign for 180°.
Further enhancement can be utilized using ME'scope. When using ME'scope, the vector arrows allow you to follow the phase angles.

Jon, you have to pay extra for modal/ods download so David may not have that option. And I believe VibPro is only standard in the gold and platinum levels--or you can pay extra for it, too. Sure looks like those kinds of things would be standard for the amount of money you pay for everything.

lawrencep
VibPro is free with the Advanced Two Channel DLP.

Free?? From CSI?

Guys, thanks for the replies and the procedures.
It seems to me being a beginner at this, it would be advantageous to test a drive train which is known to be say purely misaligned and not suffering from any other problem. This would result in data that 'conforms' to the procedure and the results not affected by looseness or unbalance etc. Would this be correct?

Vibpro Might have been free for you I do not know what kind of deal you(your Company) has with CSI. For the rest of us it is not and has not been ever since it was intro duced.
We just bought our third 2130 with the dlp/fastballII etc. and the vibpro was $4500 extra for stand alone version.

That's A fact. If you don't beleive me call your local CSI Saleman and watch him drool when you ask.

The VibPro I got wasn't standalone. It runs under AMS only. Sounds like I got a deal. I purchased ME'Scope at the same time. The whole thing came as a bundled deal. The local rep didn't have anything to do with it, this was all quoted from Noxville last year.