Danfoss VT2800 Series Design Manual

Contents

VLT ® 2800 Series- Thermal load calculation (ETR - ElectronicThermal Relay), based on present load andtime. This is compared with the rated motorcurrent I M,N and rated motor frequency f M,N .The calculations take into account the need forlower loading at low speeds due to the motor’sinternal ventilation being reduced.ETR functions 1-4 do not begin to calculate the loaduntil you switch to the Setup in which they have beenselected. This means that you can use the ETR functioneven when changing between two or more motors.Description of choice:Select No protection [0] if you do not want a warningor trip when a motor is overloaded.Select Thermistor warning [1] if you want a warningwhen the connected thermistor becomes too hot.Select Thermistor trip [2] if you want a trip when theconnected thermistor becomes too hot.Select ETR warning 1-4 if you want a warning whenthe motor is overloaded according to the calculations.You can also programme the frequency converter togive a warning signal via one of the digital outputs.Select ETR Trip 1-4 if you want a trip when the motoris overloaded according to the calculations.NB!:This function cannot protect the individualmotors in the case of motors linked in parallel.130 Start frequency(START FREQUENCY)Value:0.0 - 10.0 Hz ✭ 0.0 HzFunction:The start frequency is active for the time set inparameter 120 Start delay, after a start command.The output frequency will ’jump’ to the next presetfrequency. Certain motors, such as conical anchormotors, need an extra voltage/start frequency(boost) at start to disengage the mechanical brake.To achieve this parameters 130 Start frequencyand 131 Initial voltage are used.Description of choice:Set the required start frequency. It is a preconditionthat parameter 121 Start function, is set toStart frequency/voltage clockwise [3] or Startfrequency voltage in reference direction [4] andthat in parameter 120 Start delay a time is setand a reference signal is present.NB!:If parameter 123 is set higher than parameter130, the start delay function (parameter120 and 121) will be skipped.131 Initial voltage(INITIAL VOLTAGE)Value:0.0 - 200.0 V ✭ 0.0 VFunction:Initial voltage is active for the time set in parameter120 Start delay , after a start command. Thisparameter can be used for example for lifting/droppingapplications (conical anchor motors).Description of choice:Set the required voltage necessary to cut out themechanical brake. It is assumed that parameter121 Start function, is set to Start frequency/voltageclockwise [3] or Start frequency/voltage in referencedirection [4] and that in parameter 120 Start delay atime is set, and that a reference signal is present.132 DC brake voltage(DC BRAKE VOLTAGE)Value:0 - 100% of max. DC brake voltage ✭ 0%Function:In this parameter, the DC brake voltage is set which isto be activated at stop when the DC brake frequencyset in parameter 127 DC brake cut-in frequency isreached, or if DC braking inverse is active via a digitalinput or via serial communication. Subsequently,the DC brake voltage will be active for the timeset in parameter 126 DC brake time.✭ = factory setting. () = display text [] = value for use in communication via serial communication portMG.28.E9.02 - VLT is a registered Danfoss trademark74