Danfoss VLT 2800 Design Manual page 88

Programming
Ramp 2 is selected if a shift between ramp 1 (parameters
207-208) and ramp 2 (parameters 209-210) is required.
Logic '0' leads to ramp 1 and logic '1' leads to ramp 2.
Preset reference, lsb and Preset reference, msb make it
possible to select one of the 4 preset references in
Table 4.5.
Preset ref. msb
4 4
0
0
1
1
Table 4.5 Function of Present Reference lsb and msb
Preset reference on is used for shifting between remote-
controlled reference and preset reference. It is assumed
that [2] External/preset has been selected in parameter 214
Reference function. Logic '0' = remote-controlled references
are active, logic '1' = one of the 4 preset references is
active, as shown in Table 4.5.
Select Thermistor if a possibly integrated thermistor in the
motor is able to stop the frequency converter if the motor
overheats. The cut-out value is 3 kΩ.
R
(Ω)
4000
3000
1330
550
250
-20°C
Illustration 4.14 Resistance of a Thermistor
If a motor features a Klixon thermal switch instead, this
can also be connected to the input. If motors operate in
parallel, the thermistors/thermal switches can be
connected in series (total resistance lower than 3 kΩ).
Parameter 128 Motor thermal protection must be set to [1]
Thermistor warning or [2] Thermistor trip and the thermistor
is to be connected between a digital input and terminal 50
(+10 V supply).
86
Design Guide
Preset ref. lsb Function
0 Preset ref. 1
1 Preset ref. 2
0 Preset ref. 3
1 Preset ref. 4
 nominel -5°C
 nominel +5°C
 nominel
Danfoss A/S © Rev. May/2014 All rights reserved.
Illustration 4.15 Thermistor Connection
Select Precise stop, inverse to obtain a high degree of
accuracy when a stop command is repeated. A logic 0
means that the motor speed is ramped down to stop via
the selected ramp.
Select Precise start/stop to obtain a high degree of accuracy
when a start and stop command is repeated.
Select Pulse reference if the reference signal applied is a
pulse train (frequency). 0 Hz corresponds to parameter 204
Minimum reference, Ref
327 Pulse reference/feedback corresponds to parameter 205
Maximum reference Ref
Select Pulse feedback if the feedback signal used is a pulse
train (frequency). In parameter 327 Pulse reference/feedback
the maximum pulse feedback frequency is set.
Select Pulse input if a specific number of pulses must lead
to a Precise stop, see parameter 343 Precise stop and
parameter 344 Counter value.
Selection of Setup, lsb and Selection of Setup, msb give the
possibility to select one of the 4 setups. It is, however, a
condition that parameter 004 Active Setup is set to [5]
Multisetup.
Reset and start can be used as a start function. If 24 V are
connected to the digital input, this causes the frequency
converter to reset and the motor ramps up to the preset
reference.
Pulse counter start is used to start a counter stop sequence
with a pulse signal. The pulse width must at least be 14
ms and not longer than the count period. See also
parameter 343 Precise stop function and the VLT 2800
 [°C]
Precious Stop Instruction.
308 Terminal 53, analog input voltage
Value:
No function (NO OPERATION)
Reference (reference)
Feedback (feedback)
Wobble (WOBB.DELTA FREQ [%])
Function:
Use this parameter to select the function required to be
connected to terminal 53. Scaling of the input signal is set
in parameter 309 Terminal 53, min. scaling and parameter
310 Terminal 53, max. scaling.
Description of choice:
Select [0] No function if the frequency converter is not to
react to signals connected to the terminal.
. The frequency set in parameter
MIN
.
MAX
MG27E402
[0]
[1]
[2]
[10]