Selecting The U/F Characteristic - Siemens SIMATIC ET 200pro Original Instructions Manual

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
The required Conveyor belts, roller
torque is inde- conveyors, chain con-
pendent of the veyors, eccentric worm
speed pumps, compressors,
extruders, centrifuges,
agitators, mixers
The required Centrifugal pumps,
torque increases radial fans, axial fans
with the speed
Table 8- 12 Characteristics for special applications
Requirement Application examples
Applications with a Centrifugal pumps,
low dynamic re- radial fans, axial fans
sponse and con-
stant speed
The inverter must Drives in the textile
keep the motor sector
speed constant
under all circum-
stances.
Freely adjustable -
U/f characteristic
U/f characteristic -
with independent
voltage setpoint
SIMATIC ET 200pro FC-2 converter
Operating Instructions, 04/2015, FW V4.7.3, A5E34257324B AB
Remark
-
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.
Lower losses in the motor and inverter
than for a linear characteristic.
Remark
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.
When the maximum current limit is
reached, the inverter only reduces the
stator voltage but not the speed.
-
The interrelationship between the fre-
quency and voltage is not calculated in
the inverter, but is specified by the user.
Setting functions
8.5 Motor control
Characteristic Parameter
Linear p1300 = 0
Linear with Flux p1300 = 1
Current Control
(FCC)
Parabolic p1300 = 2
Characteristic Parameter
ECO mode p1300 = 4
or
p1300 = 7
Precise fre- p1300 = 5
quency charac- or
teristic p1300 = 6
Adjustable char- p1300 = 3
acteristic
Independent p1300 = 19
voltage setpoint
117