Danfoss VLT CDS302 Operating Instructions Manual page 74

Parameter Descriptions
7-20 Process CL Feedback 1 Resource
Option:
[2] Analog input 54
*
[3] Frequency input 29 (FC 302
only)
[4] Frequency input 33
7-22 Process CL Feedback 2 Resource
Option:
6 6
[0] No function
*
[1] Analog input 53
[2] Analog input 54
[3] Frequency input 29
[4] Frequency input 33
[7] Analog input X30/11
[8] Analog input X30/12
[15] Analog Input X48/2
7-30 Process PID Normal/Inverse Control
Option:
[0] Normal
[1] Inverse
*
7-31 Process PID Anti Windup
Option: Function:
[0] Off Continue regulation of an error when the output
frequency can no longer be adjusted.
[1] On Continue regulation of an error even when the output
*
frequency cannot be increased or decreased.
7-32 Process PID Start Speed
Range:
3000 [Set
[RPM] point ]
7-33 Process PID Proportional Gain
Range:
2.00N/A [0.00 - 10.00
N/A]
74
Function:
Function:
The effective feedback signal is made
up of the sum of up to two different
input signals. Select which input
should be treated as the source of
the second of these signals. The first
input signal is defined in 7-20 Process
CL Feedback 1 Resource.
Function:
Inverse action has to be selected for a process
loop using a suction pressure sensor to control the
system.
Function:
Enter the motor speed to be attained as a
start signal for commencement of PID
control. When the power is switched on,
the frequency converter will commence
ramping and then operate under speed
open loop control. Thereafter, when the
Process PID start speed is reached, the
frequency converter will change over to
Process PID control.
Function:
Enter the PID proportional gain. The
proportional gain multiplies the error
MG34M302 - VLT
®
Operating Instructions VLT CDS302 and CDS303
7-33 Process PID Proportional Gain
Range:
7-34 Process PID Integral Time
Range:
9.00 s
*
7-35 Process PID Differentiation Time
Range:
0.00 s
*
NOTE
This PID parameters are confortable to start any system,
but depending on its design they have to be adjusted to
follow the inertia and all responses of the real refrigeration
machine.
7-36 Process PID Diff. Gain Limit
Range:
5.0 [1.0 -
*
50.0 ]
7-38 Process PID Feed Forward Factor
Range:
0 %
*
200 %]
®
is a registered Danfoss trademark/Commercial Compressor
Function:
between the set point and the
feedback signal.
Function:
[0.01 - Enter the PID integral time. The
10000.00 ] integrator provides an increasing gain
at a constant error between the set
point and the feedback signal. The
integral time is the time needed by the
integrator to reach the same gain as
the proportional gain.
Function:
[0.00 - Enter the PID differentiation time. The
10.00 s ] differentiator does not react to a constant
error, but provides a gain only when the
error changes. The shorter the PID differ-
entiation time, the stronger the gain from
the differentiator.
Function:
Enter a limit for the differentiator gain (DG).
If there is no limit, the DG will increase when
there are fast changes. Limit the DG to
obtain a pure differentiator gain at slow
changes and a constant differentiator gain
where fast changes occur.
Function:
[0 - Enter the PID feed forward (FF) factor. The FF
factor sends a constant fraction of the reference
signal to bypass the PID control, so the PID
control only affects the remaining fraction of the
control signal. Any change to this parameter will
thus affect the motor speed. When the FF factor
is activated it provides less overshoot, and high
dynamics when changing the set point.
7-38 Process PID Feed Forward Factor is active
when 1-00 Configuration Mode is set to [3]
Process.