Siemens SIMATIC ET 200pro - Selecting the U;F Characteristic

Setting functions
8.5 Motor control
SIMATIC ET 200pro FC-2 converter
Operating Instructions, 04/2015, FW V4.7.3, A5E34257324B AB
117
The value of the output voltage at the rated motor frequency also depends on the following
variables:
● Ratio between the converter size and the motor size
● Line voltage
● Line impedance
● Actual motor torque
The maximum possible output voltage as a function of the input voltage is provided in the
technical data, also see Section Technical data (Page 219).
8.5.1.2
Selecting the U/f characteristic
Table 8- 11 Linear and parabolic characteristics
Requirement
Application examples
Remark
Characteristic
Parameter
The required
torque is inde-
pendent of the
speed
Conveyor belts, roller
conveyors, chain con-
veyors, eccentric worm
pumps, compressors,
extruders, centrifuges,
agitators, mixers
-
Linear
p1300 = 0
The inverter equalizes the voltage drops
across the stator resistance. Recom-
mended for motors less than 7.5 kW.
Precondition: You have set the motor data
according to the rating plate and have
performed the motor identification after
the basic commissioning.
Linear with Flux
Current Control
(FCC)
p1300 = 1
The required
torque increases
with the speed
Centrifugal pumps,
radial fans, axial fans
Lower losses in the motor and inverter
than for a linear characteristic.
Parabolic p1300 = 2
Table 8- 12 Characteristics for special applications
Requirement
Application examples
Remark
Characteristic
Parameter
Applications with a
low dynamic re-
sponse and con-
stant speed
Centrifugal pumps,
radial fans, axial fans
The ECO mode results in additional ener-
gy saving when compared to the parabolic
characteristic.
If the speed setpoint is reached and re-
mains unchanged for 5 seconds, the in-
verter again reduces its output voltage.
ECO mode p1300 = 4
or
p1300 = 7
The inverter must
keep the motor
speed constant
under all circum-
stances.
Drives in the textile
sector
When the maximum current limit is
reached, the inverter only reduces the
stator voltage but not the speed.
Precise fre-
quency charac-
teristic
p1300 = 5
or
p1300 = 6
Freely adjustable
U/f characteristic
- - Adjustable char-
acteristic
p1300 = 3
U/f characteristic
with independent
voltage setpoint
- The interrelationship between the fre-
quency and voltage is not calculated in
the inverter, but is specified by the user.
Independent
voltage setpoint
p1300 = 19