VLT ® 2000 Series Description of parameters I I 224 Carrier frequency (CARRIER FREQ.) Value: 2 - 16 kHz ✭ 4.5 kHz 300 Brake function (BRAKE OPTION) Value: ✭ Not applied (NOT APPLIED) [0] Applied (APPLIED) [1] Function: To avoid or reduce motor noise you can increase or reduce the carrier frequency of the frequency converter. Function: Using this parameter you can inform the VLT frequency converter that a brake function and a brake resistor have been connected. For information on sizing, see page 30. Description: It is possible to change the carrier frequency between 2 and 16 kHz. The disadvantages of operating at a high carrier frequency are: − reduced continuous output current, see page 95.
− reduced efficiency. − higher capacitive leakage current. − increased RFI radiation from the VLT frequency converter. See also the derating curve on page 95. Description: Choose Applied if you use a brake function and a brake resistor. I 306 DC braking time (DC-BRAKE TIME) Value: ✭ 0 - 60 sec. ✭ 0 sec. The disadvantages of a too low carrier frequency are a less ideal output current and motor loss. Function: Using this parameter you can record how long the DC braking must be active. I 230 Digital speed up/down (SPEED UP DOWN) Value: ✭ Disable (DISABLE) [0] Enable (ENABLE) [1] Enable and save (ENABLE+STORE) [2] Description:
When you choose the braking time you must consider if you want to maintain the braking torque or if you want to use a stop function. The DC braking time must be ≠ 0 to activate DC braking. Function: Using this parameter you can make the VLT frequency converter lock the output frequency to the latest indicated speed reference. I 307 DC-brake cut-in frequency (DC-BRK ON FREQ) Value: ✭ 0 - 500 Hz ✭ 1 Hz Description: You can choose to have either digital speed up/down (terminal 18/27 and 19) or other speed references. When you have chosen Enable you must choose Speed up (terminal 18) and Speed down (terminal 19) in parameters 402/404 and 403.
When Enable and save is selected a speed will be saved automatically after 15 seconds so that the unit remembers this frequency after new start-up. The other references will not be active so that the di- gital references cannot be combined with other references. Function: Using this parameter you can record the output fre- quency at which DC braking must start when ramping down to standstill. Description: The cut-in frequency depends on the application. The cut-in frequency must be > 0 to activate DC braking. Instead of using this parameter you can activate DC braking via terminal 27 if a DC braking time and a DC brake voltage have been recorded. ✭ = Factory setting.
Text in ( ) = Display text. The figures in [ ] are used in bus communication. 70 MG.20.B6.02 – VLT is a registered Danfoss trademark