Reference Limits - Danfoss VLT Decentral Drive FCD 302 Design Manual

Product Overview
The remote reference is calculated once every scan
interval and initially consists of two types of reference
inputs:
2 2
1. X (the external reference): A sum (see
3-04 Reference Function) of up to four externally
selected references, comprising any combination
(determined by the setting of 3-15 Reference
Resource 1, 3-16 Reference Resource 2 and
3-17 Reference Resource 3) of a fixed preset
reference (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],
[Nm] etc.).
2. Y- (the relative reference): A sum of one fixed
preset reference (3-14 Preset Relative Reference)
and one variable analog reference (3-18 Relative
Scaling Reference Resource) in [%].
The two types of reference inputs are combined in the
following formula: Remote reference=X+X*Y/100%. If
relative reference is not used 3-18 Relative Scaling Reference
Resource must be set to No function and to 0%. The catch
up/slow down function and the freeze reference function
can both be activated by digital inputs on the frequency
converter. The functions and parameters are described in
the Programming Guide.
The scaling of analog references are described in
parameter groups 6-1* and 6-2*, and the scaling of digital
pulse references are described in parameter group 5-5*.
Reference limits and ranges are set in parameter group
3-0*.

2.3.1 Reference Limits

3-00 Reference Range, 3-02 Minimum Reference and
3-03 Maximum Reference together define the allowed range
of the sum of all references. The sum of all references are
clamped when necessary. The relation between the
resulting reference (after clamping) is shown in
Illustration 2.10/Illustration 2.11 and the sum of all
references is shown in Illustration 2.12.
18
®
VLT Decentral Drive FCD 302
P 3-00 Reference Range= [0] Min-Max
P 3-03
P 3-02
-P 3-02
-P 3-03
Illustration 2.10 Reference Range=[0] Min-Max
P 3-03
-P 3-03
Illustration 2.11 Reference Range=[1] -Max-Max
The value of 3-02 Minimum Reference can not be set to less
than 0, unless1-00 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 2.12.
P 3-03
P 3-02
Illustration 2.12 Sum of all References
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MG04H102 - VLT is a registered Danfoss trademark
Resulting reference
Forward
Reverse
P 3-00 Reference Range =[1]-Max-Max
Resulting reference
P 3-00 Reference Range= [0] Min to Max
Resulting reference
Sum of all
references
Sum of all
references
Sum of all
references