Danfoss VLT HVAC Operating Instructions Manual

Also see for VLT HVAC: Instructions Design guide Instruction Operating instructions Instruction manual

Function:This function makes it possible to catch a mo-tor which is spinning freely due to a mainsdrop-out.Description of choice:SelectDisable [0] if this function is not re-quired.SelectEnable [1] to enable the frequency con-verter to “catch” and control a spinning motor.When par. 1-73 is enabled, par. 1-71StartDelay has no function.Search direction for flying start is linked to thesetting in par. 4-10, Motor Speed Direction.Clockwise [0]: Flying start search in clockwisedirection. If not successful, a DC brake is car-ried out.Both Directions [2]: The flying start will firstmake a search in the direction determined bythe last reference (direction). If not findingthe speed it will make a search in the otherdirection. If not successful, a DC brake will beactivated in the time set in par. 2-02, BrakingTime. Start will then take place from 0 Hz.1-80 Function at StopValue:Coast [0]DC hold/Preheat [1]Function:Select the frequency converter function aftera stop command or after the speed is rampeddown to the settings in par. 1-81Min Speedfor Function at Stop [RPM].SelectCoast [0] to leave the motor in freemode.SelectDC hold/Preheat [1] to energize themotor with a DC holding current (see par.2-00).1-90 Motor Thermal ProtectionValue:No protection [0]Thermistor warning [1]Thermistor trip [2]ETR warning 1 [3]ETR trip 1 [4]ETR warning 2 [5]ETR trip 2 [6]ETR warning 3 [7]ETR trip 3 [8]ETR warning 4 [9]ETR trip 4 [10]Function:The frequency converter determines the mo-tor temperature for motor protection in twodifferent ways:• Via a thermistor sensor connected toone of the analog or digital inputs(par. 1-93Thermistor Source).• Via calculation (ETR = ElectronicThermal Relay) of the thermal load,based on the actual load and time.The calculated thermal load is com-pared with the rated motor currentIM,N and the rated motor frequencyfM,N. The calculations estimate theneed for a lower load at lower speeddue to less cooling from the fan in-corporated in the motor.SelectNo protection [0] if the motor is con-tinuously overloaded and no warning or trip offrequency converter is wanted.SelectThermistor warning [1] to activate awarning when the connected thermistor in themotor reacts in the event of motor over-tem-perature.SelectThermistor trip [2] to stop (trip) thefrequency converter when the connectedthermistor in the motor reacts in the event ofmotor over-temperature.The thermistor cut-out value is > 3 kΩ.Integrate a thermistor (PTC sensor) in themotor for winding protection.Motor protection can be implemented using arange of techniques: PTC sensor in motor6. How to programme the frequency converter VLT® HVAC Drive Operating Instructions68 MG.11.A4.02 - 09.10.06. VLT® is a registered Danfoss trademark6