VLT ® 2900 Series 200 Output frequency range a selection has been of Clockwise only . Select OK - both directions [2] if the motor is able to rotate in both directions when cutting in. 0 - 200 % 10 % Select DC brake and start [3] if the frequency converter is to be able to brake the motor using the DC brake first, followed by start. It is assumed that parameters 126-127/132 DC brake are enabled. In the case of higher 'Windmilling' (rotating motor) effects, the fre- quency converter is not able to 'catch' a rotating motor without selecting DC brake and start . This parameter is only active if in parameter 100 Con- figuration the selection made is Speed regulation, closed loop .
The controller range (bandwidth) limits the output from the PID controller as a % of motor frequency f M,N . Limitations: - Too low inertia will lead to load acceleration, which can be dangerous or prevent correct catching of a rotating motor. Use the DC brake instead. The required % value can be selected for motor fre- quency f M,N . If the controller range is reduced the speed variations will be less during initial tuning. - If the load is driven, e.g. by 'Windmilling' (ro- tating motor) effects, the unit may cut out because of overvoltage. - Flying start does not work at lower values than 250 rpm.
0 - 25 V if 200V device 0 0 - 50 V if 400V device 0 The user sets the voltage by which the level for resistor braking is reduced. It is only active when resistor in parameter 400 is selected. 0 - 500 % 100 % This parameter is only active if in parameter 100 Con- figuration the selection made is Speed regulation, closed loop . The FF function sends a larger or smaller part of the reference signal outside the PID controller in such a way that the PID controller only has an influ- ence on part of the control signal. Any change to the set point will thus have a direct effect on the motor speed. The FF factor provides high dynamism when changing the set point and less overswing.
The greater the reduction value, the faster the reaction to a generator overload. Should only be used if there are problems with overvoltage in the intermediate cir- cuit. The required % value can be selected in the interval f Linear (LINEAR) [0] Square root (SQUARE ROOT) [1] MIN - f MAX . Values over 100 % are used if the set point variations are only small. In this parameter, a function is selected which converts a connected feedback signal from the process to a feedback value that equals the square root of the con- nected signal. This is used, e.g. where regulation of a flow (volume) is required on the basis of pressure as feedback signal (flow = constant x pressure ).
This conversion makes it possible to set the reference in = factory setting, () = display text, [] = value for use in communication via serial communication port 52 MG.29.A3.02 - VLT ® is a registered Danfoss trademark 452 Controller range (pid contr. range) Value: Function: Description of choice: 456 Brake Voltage Reduce (BRAKE VOL REDUCE) Value: Function: 451 Speed PID feedforward factor (feedforward fact) Value: Function: Description of choice: 461 Feedback conversion (FEEDBAC CONV.) Value: Description of choice: Function: