Operating instructions
20-82 PID Start Speed [RPM]
Range: Function:
Applica-
tion
depend-
ent
*
[Applica-
tion
depend-
ant]
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.
NOTE
This parameter will only be visible
if par. 0-02 Motor Speed Unit is set
to [0], RPM.
20-83 PID Start Speed [Hz]
Range: Function:
Applica-
tion
depend-
ent
*
[Applica-
tion
depend-
ant]
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 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 Motor Speed Unit 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.
3.18.7 20-9* PID Controller
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 PID in the
VLT HVAC Drive Design Guide, MG.11.Bx.yy for guidelines on
adjusting the PID Controller parameters.
20-91 PID Anti Windup
Option: Function:
[0] Off Off [0] The integrator will continue to change value also
after output has reached one of the extremes. This can
afterwards cause a delay of change of the output of the
controller.
[1]
*
On On [1] The integrator will be locked if the output of the
built in PID controller has reached one of the extremes
(min or max value) and therefore not able to add further
change to the value of the process parameter controlled.
This allows the controller to respond more quickly when
it again can control the system.
20-93 PID Proportional Gain
Range: Function:
0.50
*
[0.00 - 10.00 ]
If (Error x Gain) jumps with a value equal to what is set in
par. 20-14 Maximum Reference/Feedb. the PID controller will try
to change the output speed equal to what is set in
par. 4-13 Motor Speed High Limit [RPM] / par. 4-14 Motor Speed
High Limit [Hz] but in practice of course limited by this setting.
The proportional band (error causing output to change from
0-100%) can be calculated by means of the formula:
(
1
Proportional
Gain
)
×
(
Max
Reference
)
Parameter Description
VLT
®
HVAC Drive Programming Guide
130 MG.11.CA.02 - VLT
®
is a registered Danfoss trademark
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