B
My turbine vibration readings is shown as 95 um. how to I convert this reading to mm/s? If you know well please help me.
J
JFB
V = 2pi * f * X
> My turbine vibration readings is shown as 95 um <b>(X)</b>. how to I convert this reading to mm/s <b>(V)</b>.
> My turbine vibration readings is shown as 95 um <b>(X)</b>. how to I convert this reading to mm/s <b>(V)</b>.
JFB,
> V = 2pi * f * X
In the formula you cited, I presume 'f' refers to the frequency, in Hz, or RPS (Revoltions per Second) of the rotating shaft? So, in other words:
V = 2 * pi * (RPM/60) * X
Where x = micrometers (displacement)
and V = Velocity (mm/sec)
Does there need to be a conversion between micrometers and millimeters?
Thanks!
> V = 2pi * f * X
In the formula you cited, I presume 'f' refers to the frequency, in Hz, or RPS (Revoltions per Second) of the rotating shaft? So, in other words:
V = 2 * pi * (RPM/60) * X
Where x = micrometers (displacement)
and V = Velocity (mm/sec)
Does there need to be a conversion between micrometers and millimeters?
Thanks!
J
JFB
>> Does there need to be a conversion...
I didn't consider units in the expression, mainly though reminding to the OP that a rate was needed for the integration (or was that differentiation) from X to V.
Google will find several online calculators that will perform the conversion.
I didn't consider units in the expression, mainly though reminding to the OP that a rate was needed for the integration (or was that differentiation) from X to V.
Google will find several online calculators that will perform the conversion.
A
Abhishek
CSA,
I am not sure on the frequency component. Is it machine frequency or frequency of oscillation of Vibration sensor?
I am not sure on the frequency component. Is it machine frequency or frequency of oscillation of Vibration sensor?
Abhishek,
It's been a very long time since I've seen or used this formula (and it may not have been this exact formula). But, I was just trying to get JFB to comment on what 'frequency' is--or might be--in the formula he provided.
In formulae I've used in the distant past, it was always shaft speed (usually in RPS, which is an easy conversion from RPM). I don't recall if it was expressed as frequency, or RPS.
Bently Nevada monitors require a shaft speed input, from a sensor usually called a key phasor, in order to properly scale and output a displacement from a proximity sensor input. I don't know if that is RPS or RPM, but the B-N monitors I've worked always displayed that in RPM (probably because that's how most people think of shaft speed).
To derive harmonic and resonant frequencies from proximity sensors, I believe requires additional equipment to look at other components of the proximity sensor feedback.
But, again, I was just trying to get JFB to comment on what 'frequency' was in the formula he provided, and what I thought it might be--right or wrong. Hopefully JFB will comment.
It's been a very long time since I've seen or used this formula (and it may not have been this exact formula). But, I was just trying to get JFB to comment on what 'frequency' is--or might be--in the formula he provided.
In formulae I've used in the distant past, it was always shaft speed (usually in RPS, which is an easy conversion from RPM). I don't recall if it was expressed as frequency, or RPS.
Bently Nevada monitors require a shaft speed input, from a sensor usually called a key phasor, in order to properly scale and output a displacement from a proximity sensor input. I don't know if that is RPS or RPM, but the B-N monitors I've worked always displayed that in RPM (probably because that's how most people think of shaft speed).
To derive harmonic and resonant frequencies from proximity sensors, I believe requires additional equipment to look at other components of the proximity sensor feedback.
But, again, I was just trying to get JFB to comment on what 'frequency' was in the formula he provided, and what I thought it might be--right or wrong. Hopefully JFB will comment.
O
otised
Frequency would be shaft speed in RPS (=RPM/60).
The proximity probes are measuring peak-to-peak displacement of the shaft relative to the bearing casing. Velocity is the time derivative of displacement.
The proximity probes are measuring peak-to-peak displacement of the shaft relative to the bearing casing. Velocity is the time derivative of displacement.
J
JFB
Sorry, I did know there was a need for a reply.
I am not the best teacher and vibration was not my best subject.
this is the link I used to jog my memory
http://www.cbmapps.com/docs/28 there should be a lot more.
I would ASSUME you would want to determine the V from the measurement of the wave they measured, whether that was machine speed (for a 1X primary) or any of the multiples
I would have though a more pertinent question would be if the X was P-P, P or RMS.
the details of the measurements and the desired information to calculate would be needed.
I was just replying to nudge the OP in the direction to find his answer. Sorry I can't be more direct in the reply as I don't know the math that well anymore.
I am not the best teacher and vibration was not my best subject.
this is the link I used to jog my memory
http://www.cbmapps.com/docs/28 there should be a lot more.
I would ASSUME you would want to determine the V from the measurement of the wave they measured, whether that was machine speed (for a 1X primary) or any of the multiples
I would have though a more pertinent question would be if the X was P-P, P or RMS.
the details of the measurements and the desired information to calculate would be needed.
I was just replying to nudge the OP in the direction to find his answer. Sorry I can't be more direct in the reply as I don't know the math that well anymore.
JFB,
No worries. It is reasonable to expect that people can use their preferred Internet search engine to find converter applications and lots of other related information. But, what seems to happen is that when the first search they perform doesn't turn up the exact result they were looking for in the first four or five search results, they just stop looking and ask their question in some forum (not necessarily this one, but others).
As for the maths, mate, no worries! The whole subject of vibration measurement is very murky for most people--myself included. It really is a very technical subject, and there is a lot of FBM (Fine Black Magic) involved in the application of the technical aspects of the science to the art of vibration analysis.
I think this particular subject--converting from one unit of measurement to another--is rather like Fahrenheit vs Celsius. It's what one has become accustomed to, and how to relate one to the other. If I recall correctly, displacement and velocity can't be exactly directly related (without a lot of very involved mathematics), but there are formulae that can get one close enough.
Thanks for the help, though! It was better than just saying micro was a few decimal places more than milli. ;-)
And one doesn't have to be a professor to be a good technician--or even a good teacher.
No worries. It is reasonable to expect that people can use their preferred Internet search engine to find converter applications and lots of other related information. But, what seems to happen is that when the first search they perform doesn't turn up the exact result they were looking for in the first four or five search results, they just stop looking and ask their question in some forum (not necessarily this one, but others).
As for the maths, mate, no worries! The whole subject of vibration measurement is very murky for most people--myself included. It really is a very technical subject, and there is a lot of FBM (Fine Black Magic) involved in the application of the technical aspects of the science to the art of vibration analysis.
I think this particular subject--converting from one unit of measurement to another--is rather like Fahrenheit vs Celsius. It's what one has become accustomed to, and how to relate one to the other. If I recall correctly, displacement and velocity can't be exactly directly related (without a lot of very involved mathematics), but there are formulae that can get one close enough.
Thanks for the help, though! It was better than just saying micro was a few decimal places more than milli. ;-)
And one doesn't have to be a professor to be a good technician--or even a good teacher.
