Acromag limits the 851T transmitters’s sensitivity to 10mV/V for superior precision in common load cell applications with lower values. However, higher sensitivities can be accommodated because the 851T has an adjustable excitation and allows the input scale to be over-ranged up to 125%.
See full example application below.
Example: Load cell application with high sensitivity.
Sensitivity: 22.291 mV/V
Excitation: 5.00V DC
Bridge rating: 75 psi maximum
Measured range: 0 - 37.5 psi
Transmitter output range: 0-10V DC
The method for calculating the full scale output from a Bridge is:
[Sensitivity (mV/V) x Excitation Voltage (V)] x [Actual Full Scale Load / Maximum Capacity of Bridge]
For our application, this becomes:
22.2910 mV/V x 5.000 V x 37.5 psi / 75 psi = 55.7275 mV
So, measuring a 37.5 psi load, the output from the Bridge will be 55.7275 mV.
Now in our configuration software, we limit the Sensitivity to 10 mV for greater precision at the more common lower values. With this limit, the 851T expects a 50mV bridge signal at full scale load:
10 mV/V x 5.000 V = 50 mV
Figure 1 below shows how to configure the transmitter for use with the load cell.