Siemens SINAMICS S120, Function Manual

Page: 136 / 1094

Servo control
4.10 V/f control
Drive functions
136
Function Manual, 11/2017, 6SL3097-4AB00-0BP5
4.10 V/f control
For V/f control, the drive is operated with an open control loop. In this open-loop control
system, the drive does not require speed feedback and no actual current sensing. Operation
is possible with a small amount of motor data.
With V/f control, the following components and data can be checked:
● Motor Module
● Power cable between the Motor Module and motor
● Motor
● DRIVE-CLiQ cable between the Motor Module and motor
● Encoder and actual encoder value
The following motors can be operated with V/f control:
● Induction motors
● Synchronous motors
Note
In the V/f mode, the calculated actual speed value is always displayed in r0063. The speed
of the encoder (if installed) is displayed in r0061. If an encoder is not installed, r0061
displays "0".
Note
The operation of synchronous motors with V/f control is allowed only at up to 25% of the
rated motor speed.
Note
Restricted applications for V/f control
V/f control must only be used as a diagnostic function (e.g. to check that the motor encoder
is functioning correctly).
The activated V/f control blocks all other settings, for example current controller or speed
controller.