Curved Acceleration Characteristic (Sw 4 And Higher) - Siemens SINUMERIK 840C Installation Instructions Manual

10 Axis and Spindle Installation

10.5.4 Curved acceleration characteristic (SW 4 and higher)

10.5.4 Curved acceleration characteristic (SW 4 and higher)
When induction motors are used (spindle operation), allowance must be made for their speed-
dependent acceleration capability in position-controlled operation:
TorqueM
Breakdown limit
Fig. 1 Torque characteristic of induction motor
At speeds (n) above rated speed (n
the speed. Immediately above rated speed nn, there is a range of "constant power" in which
the torque (and thus also the acceleration capability) drop in proportion to 1/n. When speed n
increases further, there is a range ("breakdown limit") immediately above speed nk in which
the torque decreases in proportion to 1/(n*n).
The required parameters are selected and set in the MSD drive unit.
Speed
Setpoint
n
k
n
n
Fig. 2 Speed characteristic during acceleration (thick line)
10–66
Constant Constant
torque power
M = const M 1/n
n
n
Rated speed
), the drive acceleration capability decreases in relation to
n
The obtainable linear ramp-up time constants
increase out of proportion for higher speeds
T1
© Siemens AG 1992 All Rights Reserved
M 1/(n*n)
n n
k max
Speed n
T2 Time
6FC5197- AA50
SINUMERIK 840C (IA)
09.95