Rockwell Automation Publication 22C-UM001J-EN-E - January 2017 157
Appendix D
Application Notes
Damper Control Setup
The PowerFlex 400 allows damper control logic to be imbedded within the
drive reducing cost associated with external control hardware and software. A
system Run command can be wired directly into one of the drive inputs. Relay
outputs can be used to energize the damper to either open or close. A damper
limit switch can be wired back to the drive providing indication that the
damper is in the proper position and that it is safe for the drive to run at
commanded speed.
Example
• The System Run Command can come from a terminal block, integral
keypad, or communication port. Configure parameter P036
[Start
Source] per application requirements.
• Set one of the available digital inputs, parameter T051
...T054 [Digital
Inx Sel] to option 36 “Damper Input”. The damper end switch or limit
switch should be wired into this input.
• Set one of the available relay outputs, parameter T055
/T060 [Relay
Outx Sel] to option 2 “Motor Running”. This output should be used to
energize the damper to either open or close.
PID Setup
PID Control Loop
The PowerFlex 400 has a built-in PID (proportional, integral, differential)
control loop. The PID loop is used to maintain a process feedback (such as
pressure, flow or tension) at a desired set point. The PID loop works by
subtracting the PID feedback from a reference and generating an error value.
The PID loop reacts to the error, based on the PID Gains, and outputs a
frequency to try to reduce the error value to 0. To enable the PID loop,
parameter A152
[PID Ref Sel] must be set to an option other than 0 “PID
Disabled”.
Supply Fan
Air Flow
Damper Limit Switch
Damper Position Command
System Run Command
Outside Air
Damper
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