This shunt tool allows the user to define a shunt scaling based on a known reference shunt – used when the reference shunt resistor is not available in the hardware. For example, a 175 kOhm shunt is known to be equivalent to a load of 1000 pounds, but the hardware only supports a 100 kOhm shunt resistor. The equivalent load using the 100 kOhm shunt is computed using the following formula :
Ve = Vk * ((Rg + 2 * Rsk) / (Rg + 2 * Rse)) , where:
Ve = equivalent physical units value
Vk = known physical units value
Rg = bridge resistance
Rsk = known shunt resistance
Rse = equivalent shunt resistance
The dialog window controls are described as follows:
Shunt resistance (kOhm): The known shunt resistance (Rsk).
Physical value (units): The known physical value (Vk).
NOTE
Be careful to ensure that the known shunt scaling applies to the same leg of the bridge circuit that will be used in the hardware shunt calibration; otherwise, the polarity of the computed shunt span may be inverted.