20-73 Minimum Feedback Level
Range:
Function:
-999999.00
0 Proc-
essCtrlU-
nit*
[-999999.999 - par. 20-74 Proc-
essCtrlUnit]
The minimum allowable feedback level should be entered here in user units as defined in par.
20-12
. If the level falls below par.20-73
, auto-
tuning is aborted and an error message will appear on the LCP.
20-74 Maximum Feedback Level
Range:
Function:
999999.000
ProcessCtr-
lUnit*
[par. 20-73 - 999999.999 Proc-
essCtrlUnit]
The maximum allowable feedback level should be entered here in user units as defined in par.
20-12
. If the level rises above par.20-74
totuning is aborted and an error message will appear on the LCP.
20-79 PID Auto Tuning
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 adjustable frequency drive’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 adjustable frequency drive’s output frequency to decrease when the feedback
is greater than the setpoint reference. This is common for pressure-controlled supply fan and pump
applications.
[1]
Inverse
Inverse
[1] causes the adjustable frequency drive’s output frequency to increase when the feedback
is greater than the setpoint reference. This is common for temperature-controlled cooling applica-
tions, such as cooling towers.
20-82 PID Start Speed [RPM]
Range:
Function:
0 RPM*
[0 - par. 4-13 RPM]
When the adjustable frequency drive is first started, it initially ramps up to this output speed in
open-loop mode, following the active ramp-up time. When the output speed programmed here is
reached, the adjustable frequency drive will automatically switch to closed-loop mode and the PID
controller will begin to function. This is useful in applications in which the driven load must first
quickly accelerate to a minimum speed when it is started.
NOTE!
This parameter will only be visible if par.0-02
is set to [0], RPM.
VLT
®
HVAC Drive Programming Guide
3 Parameter Description
MG.11.C6.22 - VLT
®
is a registered Danfoss trademark
3-179
3