Exclusive control – Rockwell Automation 22B PowerFlex 40 FRN 1.xx - 6.xx User Manual

Page 146

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F-2

PID Set Up

PowerFlex 40 Adjustable Frequency AC Drive FRN 1.xx - 6.xx User Manual
Publication 22B-UM001H-EN-E

Exclusive Control

In Exclusive Control, the Speed Reference becomes 0, and the PID
Output becomes the entire Freq Command. Exclusive Control is used
when A132 [PID Ref Sel] is set to option 1, 2, 3 or 4. This configuration
does not require a master reference, only a desired set point, such as a
flow rate for a pump.

Example

In a pumping application, the PID Reference equals the Desired
System Pressure set point.

The Pressure Transducer signal provides PID Feedback to the drive.
Fluctuations in actual system pressure, due to changes in flow, result
in a PID Error value.

The drive output frequency increases or decreases to vary motor
shaft speed to correct for the PID Error value.

The Desired System Pressure set point is maintained as valves in the
system are opened and closed causing changes in flow.

When the PID Control Loop is disabled, the Commanded Speed is
the Ramped Speed Reference.

+

PID Prop Gain

PID Loop

PID Integ Time

PID Diff Rate

PID Enabled

PID Fdbk

PID Ref

PID

Error

+

+

+

PID

Output

Accel/Decel

Ramp

Freq

Command

Pump

PID Feedback =
Pressure Transducer Signal

PID Reference =
Desired System Pressure

22B-UM001.book Page 2 Wednesday, January 22, 2014 11:04 AM

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