Motor Controllers AC Variable Frequency Drives
RVBS
Specifications are subjected to change without notice.10/08/2021
19
1
Linear V/f pattern
Constant torque load
2
Auto boost
Constant torque load (To be selected
if a motor may be over-excited at no
load.)
➢
Note: If a required "load acceleration toque" is more than 50% of the rated torque, it is
recommended to select the linear V/f pattern (factory default).
- V/f characteristics
The RVBS offers a variety of V/f patterns and torque boosts, which include V/f patterns suitable for variable
torque load such as general fans and pumps or for special pump load requiring high starting torque. Two
types of torque boost are available: manual and automatic.
When the variable torque V/f pattern is selected (F32 = 0), the output voltage may be low and insufficient
voltage output may result in less output torque of the motor at a low frequency zone, depending on some
characteristics of the motor itself and load. In such a case, it is recommended to select other options.
- Torque boost: Manual torque boost (F30)
In torque boost using F30, constant voltage is added to the basic V/f pattern, regardless of the load, to give
the output voltage. To secure a sufficient starting torque, manually adjust the output voltage to optimally match
the motor and its load by using F30. Specify an appropriate level that guarantees smooth start-up and yet
does not cause over-excitation with no or light load.
Torque boost per F30 ensures high driving stability since the output voltage remains constant regardless of
the load fluctuation.
Specify the F30 data in percentage to the rated voltage at base frequency 1 (F05). At factory shipment, F30 is
preset to a level that provides approx. 100% of starting torque.
➢
Note: Specifying a high torque boost level will generate a high torque but may cause over-current due to
over-excitation at no load. If you continue to drive the motor, it may overheat. To avoid such a situation,
adjust torque boost to an appropriate level.
- Torque boost: Auto torque boost
