Siemens Sinamics S120 Function Manual page 95

Note
With synchronous motors, V/f mode is normally only stable at low speeds. Higher speeds
can induce vibrations.
Oscillation damping is activated on the basis of suitable default parameter values and does
not require further parameterization in most applications. If you become aware of
interference caused by a transient response, you have the option of gradually increasing the
value of p1338 and evaluating how this affects your system.
Note
The drive can be ramped up to the current limit (p0640) relatively quickly without the need for
extensive parameterization (when operating the drive with a variable moment of inertia, for
example).
Note the following: Only the ramp-function generator stops when the current limit (p0640) is
reached. This does not prevent the current from increasing even further. In view of this, the
parameters you set must include a safety margin relative to the current limits for the
monitoring functions to prevent the drive from switching off with an overcurrent fault.
Commissioning V/f control
1. Verify the preconditions for V/f control mode.
2. Set p0311 –> rated motor speed.
3. Set p1317 = 1 –> activates the function.
4. Activate the enable signals for operation.
5. Specify the speed setpoint.
Note
Automatic activation of additional functions
With p1317 = 1, the following functions are also activated automatically:
• Resonance damping (p1338)
• Vdc controller (p1240, p1244, p1248, p1250)
• Limitation of the up ramp as a result of M, P and I limits
• As soon as the current limit p0640 is exceeded, then the ramp-function generator is
Drive functions
Function Manual, (FH1), 01/2012, 6SL3097-4AB00-0BP2
In order to obtain a pure diagnostic mode without any influence on actual values, the
resonance damping must be deactivated (p1338 = 0).
stopped
Servo control
3.9 V/f control
93