A
The question is how to decide the lower and the higher limit of the proportional band if the gain and set point is given. The question has been asked because if we have a proportional only controller with the following settings: Proportional band = 12, setpoint- 100, manual reset = 0 and the process variable is say 90 degrees then applying the PID equation we get: Output = gain*error + manual reset = 100/12* ( (100-90)/12*100) + 0 which comes out to be 694% instead of 83.33%. 83.33% has been calculated considering that Proportional band ranges from 88 degree to 100 degree.