Reference Handling - Danfoss VLT 4000 VT Instruction Manual

Reference handling

Reference handling is shown in the block
diagram underneath.
The block diagram shows how a change in a parameter
can affect the resulting reference.
Parameters 203 to 205 Reference handling, minimum
and maximum reference and parameter 210 Reference
type define the way reference handling can be
carried out. The mentioned parameters are active
both in a closed and in an open loop.
Remote references are defined as:
• External references, such as analog inputs 53, 54
and 60, pulse reference via terminal 17/29 and
reference from serial communication.
• Preset references.
The resulting reference can be shown in the display
by selecting Reference [%] in parameters 007-010
Display readout and in the form of a unit by selecting
Resulting reference [unit]. See the section on Feedback
handling in connection with a closed loop.
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The sum of the external references can be shown
in the display as a percentage of the range from
Minimum reference, Ref
MIN
. Select External reference, % [25] in parameters
MAX
007-010 Display readout if a readout is required.
It is possible to have both preset references and
external references at the same time. In parameter 210
Reference type a choice is made of how the preset
references are to be added to the external references.
Furthermore, an independent local reference exists,
where the resulting reference is set by means of
the [+/-] keys. If local reference has been selected,
the output frequency range is limited by parameter
201 Output frequency low limit, f
202 Output frequency high limit, f
NOTE
If the local reference is active, the VLT AFD will
always be in Open loop [0], regardless of the
choice made in parameter 100 Configuration.
The unit of the local reference can be set either as Hz
or as a percentage of the output frequency range. The
unit is selected in parameter 011 Unit of local reference.
®
4000 VT
to Maximum reference, Ref
and parameter
MIN
.
MAX
75