What is a Load Cell?
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- Опубликовано: 8 июл 2024
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A load cell is a force gauge that consists of a transducer that is used to create an electrical signal whose magnitude is directly proportional to the force being measured.
There are four common types of load cells. They are pneumatic, hydraulic, strain gauge, and capacitance.
A pneumatic load cell consists of an elastic diaphragm which is attached to a platform surface where the weight will be measured.
There will be an air regulator which will limit the flow of air pressure to the system and a pressure gauge.
Thus, when an object is placed on a pneumatic load cell it uses pressurized air or gas to balance out the weight of the object.
The word hydraulic should let us know that this load cell will work by using fluid, whether water or oil.
These load cells are similar to pneumatic load cells but instead of air, they use the pressurized liquid.
A hydraulic load cell is consisting of an elastic diaphragm, a piston with a loading platform on top of the diaphragm, oil or water that will be inside the piston, and a bourdon tube pressure gauge.
When a load is placed on the loading platform the piston applies pressure to the liquid contained inside it. The pressure increase of the liquid is proportional to the applied force or weight.
A strain gauge load cell is a transducer that changes in electrical resistance when under stress or strain.
The electrical resistance is proportional to the stress or strain placed on the cell making it easy to calibrate into an accurate measurement.
The electrical resistance from the strain gauge is linear therefore it can be converted into a force and then a weight if needed.
A strain gauge load cell is made up of 4 strain gauges in a “Wheatstone” bridge configuration.
A Wheatstone bridge is an electrical circuit that measures unknown electrical resistance by balancing two legs of a bridge circuit, one of the legs contains the unknown component.
The “Wheatstone bridge” circuit provides incredibly accurate measurements. The strain gauges that are in the Wheatstone bridge are bonded onto a beam which deforms when weight is applied.
Capacitive load cells work on the principle of capacitance, which is the ability of a system to store a charge.
The load cell is made up of two flat plates parallel to each other.
The plates will have a current applied to them and once the charge is stable it gets stored between the plates.
The amount of charge stored, the capacitance, depends on how large of a gap between the plates.
When a load is placed on the plate the gap shrinks giving us a change in the capacitance which can be calculated into a weight.
Let's discuss what is a salt bag filling process?
In this application, empty bags are loaded into a machine where arms will swing down and pick up an empty bag and place it underneath a funnel.
Above the funnel, there is a fill bin that will dispense salt onto a conveyor belt with a built-in load cell in order to dispense the correct amount of salt into the bags.
As the fill bin is dispensing salt, the load cell is giving an analog input to a plc which is the current weight on the load cell.
Once the load cell is reading a weight close to the full bag weight the fill bin will close to a trickle until the correct weight is determined.
Once the load cell has the full bag weight on it, the conveyor will start dropping the salt into the funnel and down to the waiting bag.
The bag will be sealed and removed from the machine so another empty bag can be loaded.
Determining which load cell your application requires depends on how sensitive and accurate your application needs to be.
The accuracy and sensitivity are very high with capacitive.
A strain gauge type of load cell would be the next in line when it comes to accuracy and sensitivity.
While still useful in certain applications, pneumatic and hydraulic load cells would be the less sensitive and accurate types.
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#RealPars #Automation #LoadCell
I’m an engineer, 20 + years experience in automation and have worked all over the world, now a fully chartered engineer and I watch these very well presented videos with great interest!..... you guys do such a great job in conveying the content in a very easy to understand way which will hopefully bring new talent to an industry that is lacking in folks showing interest in the area.... AAESOME JOB!!!! 🤙🏻
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@@realpars I hear non-contact , radar based technology is the way to go!
Hey bro
I'm going to install polltrey feed making system.
Where i do put the weight cell under the mixer or under each of 3 silos
@@chagaarbellal4983 have you implemented it if yes can you please share details
Simple, Focused, and excellent presentation. Made me learn the core concept in a few minutes. Thank you!!!!
Glad it was helpful! happy learning
Thanks for your video. I am the load cell manufacturer in China. More people knows about load cells now!
I didn't know the type of load cell we've been using in our industry until watching this video. Thank you so much realpars team. You've really improved my automation skills
You are very welcome, Calvince! Happy to hear that our course video has been so helpful to you!
Happy learning!
Best presentation in RUclips, both by animation and explanation.
Many thanks, Rahat!
It's awesome. Thank you for your effort and time you put on making such a great educational video.
Thanks for your support, Ali! Appreciate that
Just awesome how good are those videos.Congratulations!
Great compliment! Thanks a lot for sharing.
Absolutely amazing explanation. Thanks a lot for the video and your effort in making us understand.
Happy to hear that, Sai! Thanks for sharing.
I hear non-contact , radar based technology is the way to go!
thanks a lot, very useful information as always.
Great to hear that! You are very welcome.
I don't know how I should thank you and the entire team of realpars. great work guys. keep it high
We truly appreciate your support, Avadhoot! Thanks a lot for sharing.
I hear non-contact , radar based technology is the way to go!
@@realpars
L
Thank you very much for your videos
You are very welcome, Younes! Happy learning.
Very usefull. Incredible video. Thank you.
Great to hear that. Happy learning!
Thank you REALPARS
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The best presentation.. I not only learnt the load cell working & types but also how to make technical presentation. Keep it up and all the best. 👍🏻
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Thank you very much
Very well made video, thank you
Great to hear that! Happy learning.
Thanks part of my project required this
Thanks for sharing a very informative video.
You're very welcome, Navneet!
Great mind keep you learning
This is the best RUclips channel, congrats guys!
Thanks a lot! Happy learning
thank you for this video, you make the things look easy
You are very welcome, Azer!
Amazing explanation !!
Thank you, Maulana!
it was quick and easy to understand
Glad to hear that!
Thanks for this video , I uderstand the principle of load cell .
That's amazing, thanks for your support!
Thank you for this explanation! For my school project, we need to construct a very small dimension thru-hole load cell to measure a heatsink screw's clamp force (~50 lbf). Which route would you recommend?
A thru-hole donut load cell is not inexpensive, and it will require an amplifier/electronics to complete the measurement package. For a school project, I would construct a weighing system with a half-bridge load cell using an Arduino or other inexpensive micro-controller. Search the web for "half-bridge load cell".
Thanks 🙏🏻, your presentations make my day..
Amazing to hear! Thanks for sharing.
@@realpars I hear non-contact , radar based technology is the way to go!
Thank you. I'm thinking about doing an independent project where it'll probably require me to understand how weight scales work and maybe even build one. This gave me a nice beginner's insight
That is amazing to hear, Safwan! Best of luck with your project!
I hear non-contact , radar based technology is the way to go. Also, look into radiometric weight scales on conveyor belts!
really very nice and good channel
thanks for your efforts
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Let us know whenever you have any questions!
This channel is great
Thanks for your support, Juan! Happy learning!
Real pars thanking for ur video because of ur channel I m improved my automation knowledge
Now I want do courses in online
Hi Hari,
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@@realpars 77~~~41777'"8
Great explanation!
Glad you think so!
excellent video congratulations for your channel greetings from venezuela
Thanks a lot, Alexs!
Let us know if you have any questions!
could you please explain to us how to calibrate the strain gauge LC
Normally load cells are installed on a tank in a array of 3, 4, 5, or 6 load cells, depending on the size of the tank and the total load. To calibrate, dead weights of know weight are place on the tank to simulate loading of the tank. The load cell response is recorded and the measured weights are compared to the actual weight placed on the tank. The measured weight is a sum of the weights detected by each load cell. In an ideal weight distribution, all load cells should see exactly the same load, but this is hardly ever the case. If the output from one load cell is faulty, it can be isolated by measuring the voltage at that cell in the summing junction. Because the weight response from "empty" to full can be non-linear, the tank level can be programmed as function rather than through linear scaling. The dead weights on hand should represent about 10% of the total live load (weight in tank at 100% full). Starting at empty, place the weights on the tank and record the value. Then remove the weights and fill the tank until the weight indicated matches that recorded with the weights on (replace the dead weight with water weight). Add the dead weights back and repeat the process through the entire range. Once complete, re-scale the output so that the weight indicated at 100% output matches the actual weight applied. If the progression from 0% to 100% is non-linear, use the curve to program a calculation of weight in the PLC.
good information sir thanks
Thanks for your support, Jermans! Happy learning.
Thanks real pars . We having issues at work with our liquid carbon dioxide storage tanks , we can't pick exact co2 in the tank so would calibrating them work ?
Yes, liquid CO2 flashes and causes a lot of problems with measuring level with probes or differential pressure sensors. Load cells are the best choice to measure CO2 level in a tank, and a well-calibrated system is the first step towards providing an accurate measurement. I would have a proferssional scale company come do the calibration, especially if you using the weights for trade. The professional scale companies have the best test and diagnostic equipment available to tune-up your scale systems. It is well worth the cost!
Hello, which type do you recommend for a Belt conveyor scale used in a bulk fertilizer warehouse ? for maximum accuracy. Thanks for the video
Many reputable manufacturers provide precision belt conveyors. Mettler-Toledo, Acrison, Rice Lake, Milltronics, B&H, and Hardy are all very good manufacturers. Check with each to determine which provides a model that is right for your application.
Good job
Thank you!
Amazing video sir
Thank you!
well done
Thanks a lot, Mohammed!
hello,
This is a great video to gather so much information about load cell.
I'm developing a PLC based automatic weigh feeder & i have to show flow rate in Kg/hr . so can i use this formula:
{weight(mv) * speed (mtr/sec) * 3600} / {platform length(mtr)}
** i have used 4 load cell connected in parallel to distributed the load of platform
** speed is getting using proxy pulse and calculate it using the roller circumference.
Hey, I woud like to ask you what software or website you use to visualize these devices ?
Hi Saad,
Thanks for your comment! Regarding your question, I am actually not sure about that, as our imagery is created by our graphic and animation department.
Thanks for the great video, one query please, Electro magnetic type of load cell falls in to which category out of these four
This type of load cell (electromagnetic) is often used in balances, scales, and check weighers to detect relatively small weights. I believe this type of load cell would be in a fifth category since it does not fit into the four categories described in this video.
Great !
I understand that output signal from load cell is very weak. Please explain how this weak signal is processed and calibrated to the required accuracy?
Good video. You explain the different type of load cells, and they're great. But I think it would be a good idea if you stated which load cell is being used in your examples. Given that load cells are the main topic.
I'm not sure, but the first load cell is using a Capacitive Load Cell?
Thank you for your comment. In the first example, it is likely that the load cell is a capacitance load cell since it best suited for accuracy and precision at low weights (
@@realpars Makes sense, thanks!
Can you guys do a video on PWM vs TPO explaining the advantages, usage, differences, etc...
Hey!
Great topic suggestion! Thanks for sharing that with us. I have sent this over to our course developers.
Happy learning!
Great 👍
Thank you!
Kindly make a vedio on analog and digital load cell.
Hi Nazim,
We have the following video courses on Analog, in case you missed those.
"PLC Analog Inputs and Signals" bit.ly/2U6seL3
"What is Analog Automation?" bit.ly/2NzmpVa
Additionally, we have lots of course videos on Analog in our course library. bit.ly/2L1RDSe
I will definitely forward your topic suggestion regarding a video course on Analog and Digital Load Cell to our creator team.
Happy learning!
fantastic lezion
Thanks a lot, Raffaele!
Could you explain how the impact flow meter works? Thank you
Thanks for your comment and suggestion! I will happily go ahead and pass that on to our course developers as a topic suggestion for possible future video courses.
Thanks again and happy learning!
@RealPars ; can you please make a video a bout Tank Calibration Using load cells .
Thanks for your topic suggestion! I will happily go ahead and forward this to our course developers.
I enjoy the video
Glad to hear that!
I used this particular clip to excel in my recent job interview
Great job!!
Hello Dear.
Good job.
Can you explain to me the mv/v in a load cell..
Bridge-based sensors typically specify their rated output in millivolts per volt (mV/V), where mV/V is the ratio of output voltage to the excitation voltage required for the sensor to work. Strain gauge sensors provide a voltage output that is proportional to the excitation voltage.
@@realpars THANKS SO MUCH
RealPars, could you please provide some explanations of Gas Chromatography in details,??
Hey!
Thanks for sharing your suggestion with us! I have sent this over to our course developers.
Happy learning!
@@realpars Thanks❤️❤️❤️
greetings from BENGHAZI Libya
Greetings back! Happy learning, Abdelrazek!
Nice vedio
Thank you!
6:47 the pressure in the hydraulics determine this not a load cell. but apart from that wherry professional made videos 👍
Ok Sir I am Doing a Control system Project please tell me how We write Matrixes multiplication in PLC ladder logic ?
Or how can we convert matlab code into PLC ladder logic ?
Yeah, that is going to be a nightmare. A full IEC 61131 development environment (so you can use structured text) is much more appropriate.
Matrix calculations in the PLC are most efficiently done in SCL. It could be done in ladder with some patience and determination. There is a set of example programs and documentation on the Siemens Support website that will support what you need, although the FC's are in SCL. If you don't have the SCL editor package add-on, you can still open the FC's in the ladder editor for viewing. You would then need to translate the logic into ladder.
support.industry.siemens.com/cs/document/29851674/tool-collection-of-functions-for-bit-number-and-mathematical-operations?dti=0&lc=en-WW
The only way I know of to convert Matlab to ladder logic is with a product called Simulink PLC Coder. From the comments I find online, it is not 100% efficient and may require additional massaging of the program after conversion.
Thanks.... But what type of output signal he supporting 4 to 20 ma or 0 to 10 volt or what
Capacitive and strain type load cell supports both typeof signals
Thank you sir
At my knowledge the principe is the variation of resistance and after we can add a circuit with power supply and we get analogic signal if it's not connected to computer or plc if not we can use a dc or if plc receives analogic signal we don't convert the signal with adc
S=(dR/R)/(dl/l) with A sensibility, R is resistance and I is the longer of gauge resistance
Derin A. Maleek check my answer in the comments
Most of all companies using strain gauge load cells
Nice explanation but are there any examples for the paying subscribers on HOW to code a weigh/load cell in e.g. TIA Portal?
Load cells develop millivolt signals that much be connected to an amplifier junction or some other device to convert the signals to a usable range in industrial applications since load cells cannot be directly connected to PLC I/O. When a summing junction is used, the resultant signal is typically a 4-20ma signal, which is just like any other analog input to the PLC. On the subscription site (realpars.com) we have several instructional videos on how to wire and interface analog inputs to a PLC.
❤
Nice video. Would be very nice if this videos are done in other languages e.g in German language.
Hi Basaihou,
Thanks for your comment! We currently only provide our course videos in English, you are always able to turn on the English subtitles as that might make it a bit easier for you.
Thanks for sharing your feedback, we appreciate that!
Happy learning!
Scale with 4 load cell (1000kg eich cell).. The max weigth of this scale is 1000 or 4000 kg??
4000kg. Each cell is capable of weighing 1000kg. Four cells of 1000kg capacity allow 4000kg to be weighed. The four cells are wired to a summing box, which "adds" the signals from the four cells together.
Piezoelectric force cell?
yes exactly
Piezoelectric sensors, as far I know, cannot measure static loads like weight
Thank you . Kalau bisa ada sub translate Indonesi nya. ( Im from indonesia)
You are very welcome! Happy learning, Meong!
Great video! But the narrator is pronouncing "Wheatstone bridge" incorrectly. He is saying "wet stone." The device is named after an Englishman, Charles Wheatstone. That's pronounced "wheat-stone." Or, you can say it the way the English pronounce it: /ˈwiːtstən/ (Wheat-sten) where the "e" in "sten" is barely pronounced or skipped altogether. .
Thanks for sharing your knowledge with us! I will forward this to our course developers.
9 $ or 19 $ for month ?
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Pongan un subtítulo al video para entenderle no entiendo en inglés
Hola Edwin,
¡Gracias por tu comentario! Actualmente solo proporcionamos nuestros videos del curso en inglés, siempre puede activar los subtítulos en inglés, ya que eso podría facilitarle un poco la tarea.
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