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REJECT: FA313684 How do you enter negative pressure scale in ATV320 PID function?

Issue:
The PID minimum feedback does not go below 0

Product line:
ATV320, Altivar 320

Environment:
All

Cause:
Using a transducer with negative pressure scale

Resolution:
The drive can only accept positive values (above 0)
If you have a transducer/sensor that has a negative scale for example transducer range is -14.5 to +65 you will need to make the range start at 0
  • Add -14.5 (in this example) to both your lower and higher limit of the scale
  • The new scale becomes 0 to 79.5
  • Program the PID function

Using the dial on the display, Push Enter and turn to CONF > FULL > FUN > PID.

Under the PID Regulator menu set:
PIF - PID feedback assignment

PIF1 - Min PID feedback
PIF2 - Max PID feedback
PIP1 - Min PID reference
PIP2 - Max PID reference

PII - Act. Internal PID ref
RPI - Internal PID ref
Min/Max PID Reference and Feedback are typically set to the range of the transducer.  Act. Internal PID turns on the internal set point.  Internal PID ref is the set point you want to maintain.  

Example:
You have a transducer, 4-20mA output follows a -14.5 to 65 range.  You want to maintain 40 pressure. The recommended settings would be:
You will need to change the AI3 range from 0-20mA to 4-20mA from the I-O menu then AI3 then CRL3 change it to 4.0

PIF - AI3 
PIF1 - 0
PIF2 - 79.5
PIP1 - 0
PIP2 - 79.5
PII - yes
RPI - 54.5 (notice how we added 14.5 to our setpoint as well)

This would maintain 40PSI (10.4mA feedback) in the system based on 4-20mA signal coming into AI3.  
Feedback < 10.4mA will increase motor speed. 
Feedback > 10.4mA will decrease motor speed.
If the VFD reaction needs to be reversed, set PiC, PID correct reverse, to YES.,
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