Group 40: Process Pid Set 1 - Daikin ACS320 Operation Manual

Group 40: Process PID Set 1

This group defines a set of parameters used with the Process
PID (PID1) controller .
Typically only parameters in this group are needed and are
only needed for units shipping without MicroTech controllers
but need field controls installed..
PID Controller – Basic Set-up
In PID control mode, the drive compares a reference signal
(setpoint) to an actual signal (feedback), and automatically
adjusts the speed of the drive to match the two signals . The
difference between the two signals is the error value .
Typically PID control mode is used, when the speed of a fan
or pump needs to be controlled based on pressure, flow or
temperature . In most cases – when there is only 1 transducer
signal wired to the ACS320 – only parameter group 40 is
needed .
A Schematic of setpoint/feedback signal flow using parameter
Group 40 is presented .
Figure 23: Signal Flow Diagram
In order to activate and use the PID controller Parameter
1106, page 39 must be set to value 19 .
OM 1190-1 • MD4 VFD
WARNING
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PID Controller – Advanced
ACS320 has 2 separate PID Controllers:
• Process PID (PID1) and
• External PID (PID2)
Process PID (PID1) has 2 separate sets of parameters:
• Process PID (PID1) SET1, defined in Group 40 and
• Process PID (PID1) SET2, defined in Group 41
You can select between the 2 different sets by using parameter
4027 .
Typically two different PID-Controller sets are used when the
load of the motor changes considerably from one situation to
another .
You can use External PID (PID2), defined in Group 42, in 2
different ways:
• Instead of using additional PID-controller hardware,
you can set outputs of the ACS320 to control a field
instrument like a damper or a valve . In this case, set
Parameter 4230 to value 0 . (0 is the default value .)
• You can use External PID (PID2) as an additional PID-
controller to Process PID (PID1) to trim or fine-tune the
speed of the ACS320 .
An example of the trimming is a return fan that follows the
speed of the supply fan . As the return fan needs to run faster
or slower then the supply fan in order to create under- or
overpressure, correction factors to the supply fan speed are
needed . Use External PID (PID2) in the return fan drive to
provide these corrections .
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