VLT ® 2900 Series Select how long the frequency converter should main- tain the output current at the current limit I LIM before it disconnects. At OFF parameter 409 Trip delay over- current, I LIM is not working, i.e. disconnection will not take place. The parameter must be set to LC-filter connected if an LC-filter is connected between the frequency convert- er and the motor. The LC-filter connected [3] must be used if an LC-filter is connected between the frequency converter and the motor, as otherwise the frequency converter cannot protect the LC-filter. 3000 - 14000 Hz (VLT 2903 - 2975) 4500 Hz 3000 - 10000 Hz (VLT 2980 - 2982) NB!
When the LC filter is selected the switch- ing frequency is changed to 4.5 kHz. 4500 Hz The set value determines the switching frequency of the inverter. If the switching frequency is changed, this may help to minimise possible acoustic noise from the motor. NB! The output frequency of the frequency converter can never assume a value high- er than 1/10 of the switching frequency. Off (off) [0] On (on) [1] This parameter allows connection of the overmodula- tion function for the output voltage. When the motor is running, the switching frequency is adjusted in parameter 411 Switching frequency until the frequency has been obtained at which the motor is as low-noise as possible.
Off [0] means that there is no overmodulation of the output voltage, which means that torque ripple on the motor shaft is avoided. This can be a good feature, e.g. on grinding machines. On [1] means that an output voltage can be obtained which is greater than the mains voltage (up to 5 %). NB! The switching frequency is reduced auto- matically as a function of the load. See Temperature-Dependent Switching Fre- quency under Special Conditions . When LC-filter connected is selected in parameter 412, the minimum switching frequency is 4.5 kHz. -100,000.000 - par.
415 FB MAX 0.000 Parameter 414 Minimum feedback, FB MIN and 415 Maximum feedback, FB MAX are used to scale the dis- play text to make it show the feedback signal in a process unit proportionally to the signal on the input. Without LC-filter (WITHOUT LC-FILTER) [2] LC-filter connected (LC-filter connected) [3] Set the value to be shown on the display as the mini- mum feedback signal value on the selected feedback input (parameters 308/314 Analogue inputs ). = factory setting, () = display text, [] = value for use in communication via serial communication port 46 MG.29.A3.02 - VLT ® is a registered Danfoss trademark Description of choice: Function: Description of choice:
411 Switching frequency (Switch freq.) Value: Function: 413 Overmodulation function (OVERMODULATION) Value: Function: Description of choice: Description of choice: 414 Minimum feedback, FB MIN (Min. feedback) Value: 412 Variable switching frequency (Var carrier freq.) Value: Function: Description of choice: