Reference Limits - Danfoss VLT 380-500 V Design Manual

Handling of References
The remote reference is calculated once every scan
interval and initially consists of the following reference
inputs:
•
X (External): A sum (see parameter 3-04 Reference
Function) of up to 4 externally selected
references, comprising any combination of a fixed
preset reference (parameter 3-10 Preset Reference),
variable analog references, variable digital pulse
references, and various serial bus references in
whatever unit the frequency converter is
controlled ([Hz], [RPM], [N·m] and so on). The
combination is determined by the setting of
parameter 3-15 Reference Resource 1,
parameter 3-16 Reference Resource 2, and
parameter 3-17 Reference Resource 3.
•
Y (Relative): A sum of 1 fixed preset reference
(parameter 3-14 Preset Relative Reference) and 1
variable analog reference (parameter 3-18 Relative
Scaling Reference Resource) in [%].
The 2 types of reference inputs are combined in the
following formula: Remote reference =X+X*Y/100%. If the
relative reference is not used, parameter 3-18 Relative
Scaling Reference Resource must be set to [0] No function
and parameter 3-14 Preset Relative Reference to 0%. The
frequency converter can activate the catch up/slow down
function and the freeze reference function. The functions
and parameters are described in the programming guide.
The scaling of analog references is described in parameter
groups 6-1* Analog Input 1 and 6-2* Analog Input 2, and the
scaling of digital pulse references is described in parameter
group 5-5* Pulse Input 2.
Reference limits and ranges are set in parameter group 3-0*

Reference Limits.

15.1 Reference Limits
Parameter 3-00 Reference Range, parameter 3-02 Minimum
Reference, and parameter 3-03 Maximum Reference together
define the range of the sum of all references. The sum of
all references is clamped when necessary. The relation
between the resulting reference (after clamping) and the
sum of all references is shown in Illustration 15.2 and
Illustration 15.3.
MG37N102
Design Guide
P 3-00 Reference Range= [0] Min-Max
P 3-03
P 3-02
-P 3-02
-P 3-03
Illustration 15.2 Relation between Resulting Reference and the
Sum of All References
P 3-03
-P 3-03
Illustration 15.3 Resulting Reference
The value of parameter 3-02 Minimum Reference cannot be
set to less than 0, unless parameter 1-00 Configuration
Mode is set to [3] Process. In that case, the following
relations between the resulting reference (after clamping)
and the sum of all references is as shown in
Illustration 15.4.
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Resulting reference
Forward
Reverse
P 3-00 Reference Range =[1]-Max-Max
Resulting reference
Sum of all
references
Sum of all
references
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