Output reading Load cell

[themroc]

We are in the process of purchasing a load cell in order to meassure tension force.

The Excitation Voltage is 10 VDC
and it states Rated Output (R.O.): 3 mV/V nominal

We are interested in the 100 lbs capacity range.
Would that mean at 100lbs my output signal is 10V

How do I have to interpret the 3mV/V rated output.
Can someone explain?!

 

[BobM3]

For 10 volts excitation, the full load output (of the cell only) would be 30 mV. You then would amplify that output with a load cell conditioner to get a higher voltage.

 

[themroc]

That would mean 100lbs = 30mV
50 lbs = 15mV
1 lbs = 0.3mV

Is this right?

 

[blacksea]

The load sell itself is passive component with very low sensitivity. You need conditioner as wrote before - for example from Futek:

http://www.futek.com/product.aspx?t=instrument&m=csg110

 

[themroc]

Why would a voltmeter not do the same job.
I was intending to use a data aquisition system, which I think takes readings in this range to record the loads?

 

[BobM3]

You could use a voltmeter. Generally you would want your amplifier to also supply the 10 volts of excitation. The more expensive conditioner/amplifier/excitation sources would allow you to compensate for an excitation voltage that drifted a bit from the 10.0 volts (source sensing).

If you have enough bits in your data acquisition system's a/d and not much noise on the signal then you could work direct with the 30 mV max ouput.

 

[blacksea]

Standard Analog Input of Data Acquisition systems has resolution 10bit or less. Therefore using load cell output directly isn't good idea.