Pump Down Application for the H100

Pump Down Application for the H100

A "Pump Down" application is a PID loop where the level of a tank or well is being regulated by the VFD.  The pump connected to the VFD is pumping down the level. This differs from a pressure loop where the pump is building up pressure.  Setup parameters are the same as a standard PID setup but it uses an inverse acting PID loop. This makes the sleep and wake-up function a bit different. See the below example for a better understanding.



Example
An H100 VFD is controlling the level on a tank which is 200ft deep and a set-point of 80ft. Sleep needs to activate at 78ft.  

Required Parameters

Enable PID
  1. Set PID01= Yes
  2. Set PID36= Yes to inverse the PID

Selecting and Scaling Units
  1. Set PID50=ft
  2. Set the maximum transducer value in PID53.  In this example, 200.
  3. Program the set-point (reference) source in PID10. We will leave this at Keypad
  4. Input set-point to PID11. 80ft in this example.
Feedback Setup
  1. Set the feedback source in PID20. This is most commonly I2 since transducers are usually 4-20mA
  2. Wire your transducer according to the below diagram. Watch for polarity!

Sleep Function
The sleep function will put the drive to sleep (stop it) when system demand is low. 
  1. Set the desired sleep frequency in AP1-08. This is the speed at which the VFD will go to sleep.
  2. A delay time for sleep can be set in AP1-07. 
  3. Set AP1-10=2 ft.  This is a wake up deviation level. Since the set-point is 80ft and we are using inverse PID, the VFD will wake up when we reach 82ft. (Set-point + Wake Up).
  4. Additionally, there is a wake-up delay time set at AP1-09.
PID Loop Tuning
If the PID loop is not responding quickly enough the below parameters are recommended.
  1. The default P-Gain in PID25 is 50%.  It is recommended to set this at 200% for quicker response to feedback changes.
  2. PID26 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 will make it easier for tuning and monitoring the system responsiveness.
  1. Set CNF22=18 PID Ref
  2. Set CNF23=19 PID Fbk