Vibration Analysis for beginners 3 (vibration limits, types of measurements, acceleration sensor)
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- Опубліковано 3 лип 2024
- adash.com/
In this video we will simply explain what kind of vibration measurements you should take. What vibration limits are and what an acceleration sensor and a vibration meter or analyzer is.
Here you can DOWNLOAD ADASH VIBRATION LIMIT CHARTS: adash.com/support/data-sheets...
Here you can DOWNLOAD ADASH FREE DDS SW:
adash.com/downloads/adash-sof...
The most commonly used acceleration sensor in industry is a piezoelectric acceleration sensor.
A piezoelectric crystal generates an electric charge when it is deformed - meaning compressed or stretched. To ensure deformation of the piezoelectric crystal you can see that there is some preloaded mass on it. The electric charge is transferred into the electronics of the sensor where the electric charge is converted to Voltage. This voltage is then transferred into your vibration meter through the sensor connector and cable.
In other words, the sensor is shaking on the running machine. The preloaded mass is deforming the piezoelectric crystal and this generates a Voltage signal on the output of the sensor.
A vibration meter or analyzer is an electronic device which is able to process vibration signals. If we think about it again in a very simple way, imagine that your vibration meter or analyzer is a volt meter.
The sensor is generating a Voltage signal while it is shaking on the machine. This voltage signal is transferred through the cable to your vibration device. But your vibration device will not show you volts. It is smarter that volt meter. The Vibration device is able to process the voltage signal and display vibration values such as acceleration and velocity.
There are some limit vibration values which can be considered as values indicating a worsening machine condition. We can set up the limits according to some experience with certain machines. There are also for example ADASH and ISO 10816 standards for those limit values. Or the ADASH DDS software can set up the limits automatically based on statistics from the previous measurements.
All mechanical faults which are related to the speed of the machine such as unbalance, misalignment and mechanical looseness are considered to be low frequency vibrations.
These vibrations are measured as velocity in mm/s or inches/s. (Maybe you are asking now how you can measure velocity with an acceleration sensor? With an acceleration sensor you measure an acceleration value, but the meter (analyzer) can convert the value to the velocity value). The most common frequency range of this measurement is 10 - 1000 Hz. This frequency range is also applied on ISO 10816 standards. These standards take into account the size of the machine and its foundation.
Adash has defined vibration limit values which are related to the speed of the machine (not to the size of the machine). The frequency of 10-1000 Hz is also applied.
Do not assume that a newly installed machine runs under its optimal condition! What if it was badly installed? It could be misaligned or unbalanced right from the beginning!
This way we came to the conclusion that to monitor mechanical vibrations (related to the shaft speed) of the machine we will use the measurement of Overall Velocity in mm/s (or ips) in the range of 10-1000 Hz. This measurement is represented by one number. Using the Adash DDS software we can trend this value in time and see its development.
A specific part of the machine which we want to monitor is a bearing. Bearings, as well as gears, generate vibrations on higher frequencies due to their construction - their natural frequency.
These vibrations are measured as acceleration in a “g” value. The frequency range of this measurement may vary a lot and you should find out what would be the best for your particular bearing.
But let’s keep it simple and define your measurement of acceleration in the range of 500 - 16 000 Hz.
Adash has defined bearing vibration limits related to the speed of the machine again. The mentioned frequency range of 500 - 16 000 Hz has been applied.
So, the second measurement which we will include in our regular machinery measurement will be Overall Acceleration in g in the range of 500 - 16000 Hz. It is represented by one number. Again, using DDS software we can trend this value in time and see its development.
00:00 - 01:50 Acceleration Sensor - principle
01:50 - 02:40 Vibration Meter and Analyzer - principle
02:40 - 09:31 Vibration limits and Measurements types - Наука та технологія
Great material for beginners vibration analysts.
Good job Vaclav and team Adash!
Hello sir , I have Raw data of Acceleration in x , y and z axis can I get frequency weighted acceleration from this data ?
Thank you for this video series, appreciate them 👍🏻
this modules are very outlined and very well explained its way better than our instructor thank you very much for this valuable information
Very good lecture regarding vibration analysis.
Thanks for liking
Awesome 👏
good explain
Very helpful for understanding the basics. watched all 3 videos "Vibration Diagnostics for beginners" uploaded by you so far. anxiously waiting for next in the series. Please upload soon. Thanks in advance. 🙂
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Thanks now I understand
very nice
Easy to understand ..We were using the acceleration measurement for some engine parts and i was confused with units of Acceleration which was measured in G and the reason behind it..i am thankful for it..I would like also know if you could explain the strain were some time measured in Pa while measuring on strain gauge...but normally it is dimensionless.as it change in length over original length
We would love to answer question from vibration analysis field :-)
Hello sir , I have Raw data of Acceleration in x , y and z axis can I get frequency weighted acceleration from this data ?
Why apply negative voltage for vibrating sensor sir
Appreciate if you could help us derive the values of velocity and displacement from g values, and how accurate are these derived values.
Download and install our Virtual Unit software. Go to Menu / Calculator / Vibration Units Converter
Virtual Unit download link: adash.com/software-vibration-diagnostics/virtual-unit
Why to take horizontal, vertical and axial reading in Moter
Ideally you would like to get as much information about the machine you can. Horizontal measurement discovers unbalance problems, vertical gives you info about mechanical looseness. But normally it is ok to place the sensor on 45 degrees on the bearing house and therefore to get vibration signal from both directions. You should definitely take at least one axial measurement on the machine because this direction is sensitive on misalignment. Take this one near coupling on the motor DE for example.
In a pump motor set is it a good idea to decouple the set and check the motor separately for vibration or it should only be checked in load condition?
Decoupled components will vibrate differently. It is actually important to measure your machinery set together.
Can you help me with that please vibration of motor at standstill is zero after running its increasing 1.3.till 30 .what is the problem?????? First axial measurement was high.
Dear sir. Making analysis just from one sentence which you wrote is really impossible. Write me more details about your measurements on revaj@adash.cz and we can discuss it further.
It was really beneficial for me as I am conducting research on measuring the vibration level of the transformer. Is vibration in the transformer windings related to the high freq vibration?
Transformer vibrations would not be related to high frequencies. They will be related to line frequency. Therefore depending on your location it will be around frequency of 50 or 60 Hz and its harmonics. However we have to admit that we have more experiences with rotating equipment vibrations.
Hello,
Please, for the calculation of the shaft rotation frequency (f=RPM/60) do we take the rotation speed indicated on the nameplate or do we measure the speed on the spot during the collection of vibrations data's. In this case the rotation speed will be variable every time when we collect data and Wich tachymeter do you recommend.
Thanks to anyone who can help me to clarify this point
To measure speed during taking of vibration data will be more precise. Of course to trend the vibration data it is good to measure the machine under same speed and load. We are using laser speed probe with reflective tape glued on the shaft.
hello, how to use ISO 6954-1984 guidelines if i have velocity,acceleration & displacement data?
Sorry sir, no experiences with these standards.
Good one! i have a query, In case of 3 Axis vibration sensor, which axis value should be taken for threshold limit as per ISO standards. Axial or Radial vertical or Radial Horizontal
Can you use on of these vibration meters to measure subtle vibrations from washing machine next door by putting it on the floor or wall.
Yes, you can. But it depends how far the washing machine will be from the sensor? To put the sensor on the floor will be better and probably to use acceleration sensor with higher sensitivity of 500 mV/g or even 1000 mV/g.
@@AdashCompany I sleep next door to apartment. Their washing machine sends subtle non random pulsing vibrations hardly detectable unless you are sitting or lying down. I think it even damaged the back of my head brain? My head behind feels permanently hot. Would like to record vibrations to put pressure on selfish neighbour who runs machine all night every night and also sometimes in the day. My mother is suffering this every night even with lockdown and her cancer treatment. Anyway thanks for advice.
@@Bea_remembrance Vibrations can be surely measured. Maybe also sound level meter will help. But we are sorry, this case is out of our expertise.
I check my vibrate
A strange question. But will an accelerometer give different readings is stuck to a device on different planes. ( eg... like the instruction show, as opposed to on its side ? )
I mean I know it should. But trying to figure out how / why someone did this in a real life situation designed to test multiple vibration plates.
It will surely give different readings on different planes. Motor drive end has some other component connected. So there will be different vibrations than on non drive end. Also question of how the mchachines is anchored on each plane and other aspects.
Is a vibration sensor such as the one sensitive enough for me to detect and measure vibrations from a cd player, and also detect and compare the difference when adding special dampening feet under the cd player?
To measure vibrations is of course good method how to compare the difference with/without damping.
Acceleration sensor shown on the video is most common for industrial usage. I'm afraid it won't be suitable for your application. You should try miniature accelerometers which are available on the market. They are small in size and weight and therefore they have better response for measuring on small equipments such as CD players.
@@AdashCompany Thankyou for your reply. I couldn't find anything online when searching for "miniature accelerometer", but I did find a modest looking "digital vibration meter", would that likely work? The device appears medium in size and it has the stethoscope device attached on the end of the cable (the acceleration sensor). The device seems to display 3 different readings on the digital screen. It shows "VEL", "ACC", and "DISP". Would this likely work for reading low level vibrations such as from cd player? Thankyou for your patience I have know one else to ask.
@@jamest4198 Basically any vibration meter can do the job for you.
But it is really more about a sensor which should be small in size. We don't want to do an advertisement to sensor producers over here, so please write to our sales department and they will guide you to select apropriate sensor. Email: revaj@adash.cz
After we get velocity value, how do we differentiate wheter the problem is unbalance, misalignment or looseness?.
You can not differentiate problems with just one value. Each fault has a specific pattern in FFT. Unbalance usually has significant peak only on speed frequency although it could be also related to electrical problem. It seems it is a good topic for our next video.
2/12/2021
How do we convert acceleration value into velocity and displacement?
v = a / 2πf and d = v / 2πf
Dear sir, do you have any analyzer which can be used for shop balancing [2 planes] method also ...
I undoubtedly trust on ADASH, beacsus of it's preciseness,,
Digivibe M30 from Erbessed Instruments, can be used as 'vibration analyzer and on-site balancer' and also can be used for shop balancing purpose[only cradles/bearing suspensions/bearings and drive motor required seperately]
In short, will it be great to use for both shop and on-site analysis and balancing purposes,,,,, instead to use them seperately
You can use any Adash analyzer which is is capable of 2 plane balancing. Therefore:
VA3Pro: adash.com/portable-vibration-devices/a4300-va3-vibration-analyzer
VA5Pro: adash.com/portable-vibration-devices/a4500-va5-vibration-analysis-thermal-imaging-ultrasound
A4404-SAB: adash.com/portable-vibration-devices/a4404-sab-pocket-vibration-analyzer
Then you will need only cradles/bearing suspensions/bearings and drive motor as you mentioned.
May be a dumb question but if i was using a piezo disk sensor which outputs the vibration, how could i plot the acceleration from the vibration data?
The piezo disk is connected closely to the shaft of a dc motor
What device you have to process the data from piezo sensor? Normally a common industrial sensor has an output in mV/g and analyzer is able to plot the vibration data in acceleration, velocity, displacement.
@@AdashCompany I'm using an ADC so that I can plot the data in visual studio.
What is the displacement and acceleration limit of vibration (Drms and Arms) according to the ISO standered ?
ISO standards mentioned in this video takes into account only velocity measurement.
@@AdashCompany sir, I am trying to replicate the vibrations developed by industrial motor with a vibration motor, but I only know the velocity limit from iso. But what is the value of acceleration, frequency and displacement. Please help me 🙏🙏
@@mechzion01 ISO standards takes into account only velocity measurement. There are no official limit values for acceleration and displacement. Frequency is different physical quantity.
@@AdashCompany how to choose a vibration motor , to replicate the vibration caused by industrial motor?..plz plz plz plz help
@@mechzion01 Even a small workshop grinder can simulate vibrations of industrial motors as you can see in some of our videos.
6:50
How do we convert output voltage value into acceleration in g for vibration sensor?
The acceleration sensor has a sensitivity expressed in mV/g (sens), ie sens = mV/g.
If you want to find out what voltage will come from the sensor at a certain acceleration, then mV = sens * g
If you want to find out what is the acceleration when you know the voltage from the sensor, then g = mV / sens
Thanks@@AdashCompany . But we have calculated as Acc in g = (o/p voltage - Zero o/p voltage) / sensitivity.
Can u pls tell me is it right or not?
@@gayathris4489
Your question is not very clear to us.
There is a dynamic signal on the sensor output means voltage according to acceleration. No matter if you measure RMS, 0-P or P-P the conversion is always the same. For example if you measure 200 mV 0-P with 100 mV/g sensitivity then it is 200/100= 2g 0-P
Send us email on revaj@adash.cz if you want to discuss this issue in details.
How do we convert acceleration value into speed?
Do you mean into velocity? v = a/2*π*f
@@AdashCompany Don't we then need to integrate the acceleration signal?
@@MatheusMarques-xu8fd If you want to get velocity from acceleration then yes, you do integration v = a/2*π*f