Figure 8-2: Current And Torque Curves For Star-Delta Starting - Siemens sirius System Manual

Star-delta starter
SIRIUS System Manual
GWA 4NEB 430 0999-02b
After a delay, the motor windings are switched from a star to a delta config-
uration. The motor current for star starting is only about 1/3 of that required
for delta starting (motor torque, too, is reduced to approximately 1/3 of the
delta torque).
Disadvantages:
• 6 motor cables are necessary
• Switching surges occur (in the current and torque transients)
• The startup cannot be adapted to the system environment
• Installation is relatively complicated and time-consuming
• More space is needed in the cubicle
I
Starting current for d
I d
A
Starting current
for */d-start
*=
I
A
1/3 I d
A
=1/3 M

Figure 8-2: Current and torque curves for star-delta starting

3RW3 semiconductor motor control unit
M
M d
A
d
M *
A
A
n
n n
syn
*n
rated
M
d
motor for
M *
motor for
n
*n
M
load
n
n
syn
rated
8-7