I have to purchase a new load cell for an experimental application.

The rated resolution of all the load cells I have considered is infinite.

The output is 2mV/V and the capacity I need is 5 lb.

In one of the load cells data sheet there is a 'total error' expressed in porcentage of rated input, while in most of the other ones there are three or more different values: Hysteresis, Non-linearity, Non repeatability and sometimes Zero balance. All of these are expressed in porcentage of full scale output.

In order to compare the accuracy of these load cells I would like to know how to calculate the total error of each of them. I suppose in fact that the total error is a good expression of the accuracy of the transducer.

Looking on the web I understood the meaning of these words (repeatability, linearity etc..) but I couldn't find how to put them together -if possible- into a sinlge significant value.

Hope you can help me with this.

Regards,

Libero

 

Hi,
Different manufacturers provide different specifications. Combined error , total error , non-linearity , hysteresis....

Total error may not represent the TOTAL ERROR of a laod cell.

What is your accuracy / error requirement?

You cannot add all the errorsd to find the load cell erros because all errors do not happen at the same load / condition line some at zero load , some at 50% load, some at full load adnd some some with tim e and some with temperature.

The best way to find a solution is to ask the manufaturer the "accuracy/Class of the load cell as per ,say, OIML standards.", before you buy a lad cell and make sure it meets your requirement !

Regards
Saji

 

The single significant value you are looking for comes from an uncertainty budget you must perform for the load cell including the load cell calibration data. Your uncertainty components will include (but are not limited to): nonlinearity, repeatability, hysteresis, temperature effects, uncertainty of calibration data, etc. That will take care of the load cell uncertainty, then you need to do a similar uncertainty budget on the data acquisition system you are using to gather the load data. Your uncertainty components for the data system will include (but are not limited to): load cell uncertainty, transfer standard (used to calibrate the data channel), resolution, noise, nonlinearity, repeatability, hysteresis, temperature effects, etc. The final result you end up with is the total uncertainty (a single value) for that load cell and that data channel. When I do uncertainty budgets, I like to include a variety of data channels and a range of load cells so the single uncertainty value I come up with is good for an entire data system input range and an entire range of load cells. I hope this helps.

Regards,

 

dear sir
in my case i am having linearity and histerisis only. how can i find the combined accuracy of that load cell which is having 5000n range.

with regards
esakki

 

I have a question.. if i put one load cell over another will the error add up or lets say what happens to the error of both the load cells?

 

What type of load cell is it ? (compression/ tension/universal/S-type etc). Why do you want to put one load cell over the other (for comparison/ calibration/ transfer standard etc).

 

Research the word "uncertainty". This may answer your questions.