Setting up PID on the S100, G100, and iS7 VFDs

Setting up PID on the S100, G100, and iS7 VFDs

PID (which stands for Proportional, Integral, and Derivative) control is a process control loop used to regulate a variable such as temperature or pressure.  In terms of VFDs, this is usually accomplished with a transducer that provides feedback to the VFDs analog input. A set-point is setup in the VFD. The purpose of the PID loop it to automatically adjust and regulate motor speed to achieve a stable feedback as close to the set-point as possible. 


Enable PID

  1. Set Ap/APP1=2 – Process PID
  2. Set Ap/APP28  = 1 – Normal PID 
    Important Step
Selecting and Scaling Units

Be aware that units are always a % on these VFDs .

  1. Set the maximum transducer value in Ap/APP43.  Example, a 150PSI transducer would be set to 150%.
  2. Program the set-point (reference) source in Ap/APP20. Most applications use keypad.
  3. Input the desired set-point, the value you want to maintain, in Ap/APP19. This is a % of APP43!



Feedback Setup
  1. Set the feedback source in Ap/APP21. This is most commonly I1 or I2 since transducers are usually 4-20mA.
  2. Wire your transducer according to the below diagram.

     Watch for polarity!


Submersible Pumps
Submersible pumps often use a thrust bearing. The pump must ramp up to 30Hz within 1 second in order for the thrust bearing to be properly lubricated. Setup the below parameters on submersible pump applications.
  1. Set Ad/ADV60=30Hz.  This is our accel/decel switch frequency.
  2. Set bA/BAS70=1 second and bA/BAS71=1 second. This makes the VFD ramp up to 30Hz in 1 second. It will also ramp down from 30 to 0Hz in 1 second.
PID Loop Tuning
If the PID loop is not responding quickly enough the below parameters are recommended.
  1. The default P-Gain in Ap/APP22 is 50%.  It is recommended to set this at 200% for quicker response to feedback changes.
  2. Ap/APP23 is the integral time, and defaults to 10 seconds. Decrease this time to about 2 seconds to achieve a tighter PID loop.
Monitoring
The below settings will pin the set-point and feedback to the main monitor display. This applies to the iS7 and S100 when using the LCD keypad. This will make it easier for tuning and monitoring the system responsiveness.
  1. Set CNF22=18 PID Ref
  2. Set CNF23=19 PID Fbk
If you do not have an LCD keypad or have a G100, use parameter AP.18 to see feedback.

LSE PID Guide (Cheat Sheet) for ALL LSE AC Drives
Quick view below or download the spreadsheet attachment.

Refer to PID USER GUIDE, as attached.