Selecting The U/F Characteristic - Siemens SINAMICS G120 Operating Instructions Manual

The inverter increases its output voltage – also above the motor rated speed up to the
maximum output voltage. The higher the line voltage, the greater the maximum inverter
output voltage.
If the inverter has reached its maximum output voltage, then it can only increase its output
frequency. From this point onwards, the motor is operated in field weakening; this means
that the available torque linearly decreases with increasing speed.
The voltage boost of the characteristic improves motor behavior at low speeds.
9.6.1.2

Selecting the U/f characteristic

Procedure
With the Operator Panel:
 Select the suitable characteristic curve
Table 9- 27 Linear and parabolic characteristics
Requirement Application examples
The required Conveyor belts, roller
torque is conveyors, chain
independent of the conveyors, eccentric
speed worm pumps,
compressors,
extruders, centrifuges,
agitators, mixers
The required Centrifugal pumps,
torque increases radial fans, axial fans
with the speed
SINAMICS G120C frequency converter
Operating Instructions, 03/2012, FW V4.5, A5E02999804B AB
and set parameter p1300.
Remark
-
The inverter equalizes the voltage drops
across the stator resistance.
Recommended for motors with a low
power rating.
Precondition: You have set the motor data
according to the rating plate and have
performed the motor identification after
the basic commissioning.
Lower losses in the motor and inverter
than for a linear characteristic.
Using STARTER:
 Go online with STARTER.
 Select the U/f characteristic curve in one of
the screen forms "speed controller" or "U/f
control".
Characteristic
Linear
Linear with Flux
Current Control
(FCC)
Parabolic
Functions
9.6 Motor control
Parameter
p1300 = 0
p1300 = 1
p1300 = 2
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