Siemens SIMOTICS T-1FW68, Configuration Manual

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Technical data and characteristics
6.1 Explanations
1FW68 radial segment motors
132
Configuration Manual, 08/2021, A5E51132930B AA
Torque-speed diagram with field weakening
1 S1 duty
2 S1 duty with field weakening
3 Voltage limit characteristic
4 Limit characteristic for S1 duty
5 Voltage limit characteristic with field weakening
6 Rated operating point at M
N
, n
N
, I
N
7 Operating point at M
MAX
, I
MAX
, n
MAX,MMAX
8 Torque M
0
at speed n = 1 r/min
Figure 6-4 Schematic description of the torque-speed diagram
The voltage induced in the motor winding increases as the speed increases. The
difference between the DC link voltage of the converter and the induced motor voltage
can be used to impress the current.
The torque must be reduced if the voltage limit of the infeed module is reached at
speed n.
All operating points that can be achieved with the motor lie below the "voltage limiting
characteristic".
For the SINAMICS S120 drive system, as a result of the field weakening function, when
the "voltage limiting characteristic" is reached, then the voltage induced in the motor
winding is automatically compensated. As a consequence, the speed range of a motor
can be extended without requiring a larger power module. The operating points for field
weakening that can be reached when motoring, are located to the left or below the
"voltage limiting characteristic with field weakening" and to the right of the "voltage
limiting characteristic".