Operating instructions

20-70 Closed Loop Type
Option: Function:
This parameter defines the application
response. The default mode should be
sufficient for most applications. If the
application response speed is known, it can
be selected here. This will decrease the time
needed for carrying out PID autotuning. The
setting has no impact on the value of the
tuned parameters and is used only for the
autotuning sequence.
[0]
* Auto
[1] Fast Pressure
[2] Slow Pressure
[3] Fast Tempera-
ture
[4] Slow Tempera-
ture
20-71 PID Performance
Option: Function:
[0] * Normal Normal setting of this parameter will be suitable for
pressure control in fan systems.
[1] Fast Fast setting would generally be used in pumping
systems, where a faster control response is desirable.
20-72 PID Output Change
Range: Function:
0.10 * [0.01 -
0.50 ]
This parameter sets the magnitude of step change
during autotuning. The value is a percentage of
full speed. I.e. if maximum output frequency
inpar. 4-13 Motor Speed High Limit [RPM]/
par. 4-14 Motor Speed High Limit [Hz] is set to 50Hz,
0.10 is 10% of 50Hz, which is 5Hz. This parameter
should be set to a value resulting in feedback
changes of between 10% and 20% for best tuning
accuracy.
20-73 Minimum Feedback Level
Range: Function:
-999999.000
ProcessCtrlU-
nit
*
[Applica-
tion
dependant]
The minimum allowable feedback
level should be entered here in User
units as defined in
par. 20-12 Reference/Feedback Unit. If
the level falls below
par. 20-73 Minimum Feedback Level,
autotuning is aborted and an error
message will appear on the LCP.
20-74 Maximum Feedback Level
Range: Function:
999999.000
ProcessCtrlU-
nit
*
[Applica-
tion
dependant]
The maximum allowable feedback
level should be entered here in User
units as defined in
par. 20-12 Reference/Feedback Unit. If
the level rises above
par. 20-74 Maximum Feedback Level,
autotuning is aborted and an error
message will appear on the LCP.
20-79 PID Autotuning
Option: Function:
This parameter starts the PID autotuning sequence.
Once the autotuning has successfully completed
and the settings have been accepted or rejected by
the user, by pressing [OK] or [Cancel] buttons on
the LCP at the end of tuning, this parameter is reset
to [0] Disabled.
[0]
* Disabled
[1] Enabled
3.18.6 20-8* PID Basic Settings
This parameter group is used to configure the basic operation
of the frequency converter’s PID Controller, including how it
responds to a feedback that is above or below the setpoint,
the speed at which it first starts functioning, and when it will
indicate that the system has reached the setpoint.
20-81 PID Normal/ Inverse Control
Option: Function:
[0] * Normal Normal [0] causes the frequency converter’s output
frequency to decrease when the feedback is greater
than the setpoint reference. This is common for
pressure-controlled supply fan and pump applica-
tions.
[1] Inverse Inverse [1] causes the frequency converter’s output
frequency to increase when the feedback is greater
than the setpoint reference. This is common for
temperature-controlled cooling applications, such as
cooling towers.
Parameter Description
VLT
®
HVAC Drive Programming Guide
MG.11.CA.02 - VLT
®
is a registered Danfoss trademark 129
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