VLT ® 2900 Series Term .29 Term. 33 Freeze ref/ freeze outp. Function 0 0 1 No speed change 0 1 1 Speed up 1 0 1 Speed down 1 1 1 Speed down Freeze reference can be changed even if the frequency converter has stopped. The reference will also be saved if the mains are disconnected. Catch-up/Slow-down is selected if the reference value is to be increased or reduced by a programmable per- centage value set in parameter 219 Catch-up/Slow- down reference . 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 k Ω).
Parameter 128 Motor thermal protection must be pro- grammed for Thermistor warning [1] or Thermistor trip [2] and the thermistor is to be connected between a digital input and terminal 50 (+ 10 V supply). Ramp 2 is selected if a shift between ramp 1 (param- eters 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 makes it possible to select one of the four preset references, see the table below: Precise stop, inverse is selected 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.
Precise start/stop is selected to obtain a high degree of accuracy when a start and stop command is repea- ted. Pulse reference is selected if the reference signal ap- plied is a pulse train (frequency). 0 Hz corresponds to parameter 204 Minimum reference, Ref MIN . The fre- quency set in parameter 327 Pulse reference/feedback corresponds to parameter 205 Maximum reference Ref MAX . Preset reference on is used for shifting between re- mote-controlled reference and preset reference. It is assumed that External/preset [2] has been selected in parameter 214 Reference function .
Logic '0' = remote- controlled references are active, logic '1' = one of the four preset references is active, as can be seen from the table above. Pulse feedback is selected if the feedback signal used is a pulse train (frequency). In parameter 327 Pulse reference/feedback the maximum pulse feedback fre- quency is set. Thermistor is to be selected if a possibly integrated thermistor in the motor is to be able to stop the fre- quency converter if the motor overheats. The cut-out value is 3 k Ω. Pulse input is selected 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 gives the possibility to select one of the four setups. It is, however, a condition that parameter 004 is set to Multisetup . Reset and start can be used as a start function. If 24 V are connected to the digital input, this will cause the = factory setting, () = display text, [] = value for use in communication via serial communication port 38 MG.29.A3.02 - VLT ® is a registered Danfoss trademark Slow-down Catch-up Function 0 0 1 1 0 Unchanged speed 1 Increase by % value 0 Reduce by % value 1 Reduce by % value Preset ref. msb Preset ref. Function lsb 0 0 1 1 0 Preset ref. 1 1 Preset ref. 2 0 Preset ref. 3 1 Preset ref. 4