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enabled (see par. group 3-1*) will be used as
the PID controller’s setpoint reference.
Multi-setpoint minimum
[5] sets up the PID
controller to calculate the difference between
Feedback 1 and Setpoint 1, Feedback 2 and
Setpoint 2, and Feedback 3 and Setpoint 3. It
will use the feedback/setpoint pair in which
the feedback is the farthest below its corre-
sponding setpoint reference. If all feedback
signals are above their corresponding set-
points, the PID controller will use the feed-
back/setpoint pair in which the difference
between the feedback and setpoint is the
least.
NOTE
If only two feedback signals are
used, the feedback that is not to
be used must be set to
No Func-
tion in par. 20-00, 20-03 or
20-06. Note that each setpoint
reference will be the sum of its
respective parameter value
(20-11, 20-12 and 20-13) and
any other references that are
enabled (see par. group 3-1*).
Multi-setpoint maximum
[6] sets up the PID
controller to calculate the difference between
Feedback 1 and Setpoint 1, Feedback 2 and
Setpoint 2, and Feedback 3 and Setpoint 3. It
will use the feedback/setpoint pair in which
the feedback is farthest above its correspond-
ing setpoint reference. If all feedback signals
are below their corresponding setpoints, the
PID controller will use the feedback/setpoint
pair in which the difference between the feed-
back and the setpoint reference is the least.
NOTE
If only two feedback signals are
used, the feedback that is not to
be used must be set to
No Func-
tion
in par. 20-00, 20-03 or
20-06. Note that each setpoint
reference will be the sum of its
respective parameter value
(20-21, 20-22 and 20-23) and
any other references that are
enabled (see par. group 3-1*).
20-21 Setpoint 1
Value:
Ref
MIN
par.3-02 - Ref
MAX
par.
3-03 UNIT (from par. 20-12) 0.000
Function:
Setpoint 1 is used in closed-loop mode to en-
ter a setpoint reference that is used by the
adjustable frequency drive’s PID controller.
See the description of
Feedback Function
, par.
20-20.
NOTE
Setpoint reference entered here
is added to any other references
that are enabled (see par. group
3-1*).
20-22 Setpoint 2
Value:
Ref
MIN
- Ref
MAX
UNIT (from par.
20-12) 0.000
Function:
Setpoint 2 is used in closed-loop mode to en-
ter a setpoint reference that may be used by
the adjustable frequency drive’s PID control-
ler. See the description of
Feedback Func-
tion
, par. 20-20.
NOTE
The setpoint reference entered
here is added to any other ref-
erences that are enabled (see
par. group 3-1*).
20-81 PID Normal/Inverse Control
Value:
Normal [0]
Inverse [1]
Function:
Normal
[0] causes the adjustable frequency
drive’s output frequency to decrease when the
feedback is greater than the setpoint refer-
6. How to program the adjustable frequency
drive VLT ® HVAC Drive Instruction Manual
92
MG.11.A4.22 - VLT
®
is a registered Danfoss trademark
6