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2.17.6 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
[1]
Inverse
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
applications.
Inverse
[1] causes the frequency converter’s output frequency to increase when the feedback is
greater than the setpoint reference.
20-82 PID Start Speed [RPM]
Range:
Function:
0 RPM*
[0 - par. 4-13 RPM]
When the frequency converter 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 frequency converter 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.
NB!
This parameter will only be visible if par.0-02
is set to [0], RPM.
20-83 PID Start Speed [Hz]
Range:
Function:
0 Hz*
[0.0 - par. 4-14 Hz]
When the frequency converter is first started, it initially ramps up to this output frequency in Open
Loop Mode, following the active Ramp Up Time. When the output frequency programmed here is
reached, the frequency converter will automatically switch to Closed Loop Mode and the PID Con-
troller 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.
NB!
This parameter will only be visible if par.0-02
is set to [1], Hz.
20-84 On Reference Bandwidth
Range:
Function:
5 %*
[0 - 200 %]
When the difference between the feedback and the setpoint reference is less than the value of this
parameter, the frequency converter’s display will show “Run on Reference”. This status can be
communicated externally by programming the function of a digital output for
Run on Reference/No
Warning
[8]. In addition, for serial communications, the On Reference status bit of the frequency
converter’s Status Word will be high (1).
The
On Reference Bandwidth
is calculated as a percentage of the setpoint reference.
2.17.7 PID Controller, 20-9*
This group provides the ability to manually adjust this PID Controller. By adjusting the PID Controller parameters the control performance may be
improved. See section on
PID
in the chapter
Introduction to VLT AQUA Drive
in the
VLT AQUA Drive Design Guide
for guidelines on adjusting the PID
Controller parameters.
2 Parameter Description
VLT
®
AQUA Drive Programming Guide
168
MG.20.O4.02 - VLT
®
is a registered Danfoss trademark
2