Siemens SIRIUS System Manual

3RW3 semiconductor motor control unit
SIRIUS System Manual
GWA 4NEB 430 0999-02b
8-7
Star-delta starter
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
Figure 8-2: Current and torque curves for star-delta starting
I
I
A
d
I
A
*
=
Starting current for
d
Starting current
for
*
/
d
-start
n
n
n
syn
*
n
rated
M
M
A
d
M
motor for
d
M
motor for
*
M
A
*
=1/3 M
A
d
M
load
n
n
n
syn
*
n
rated
1/3 I
A
d

Siemens SIRIUS Specifications

General

Product brand name	Siemens
Series	SIRIUS
Coil Voltage	24V DC, 110V AC, 230V AC
Switching Capacity	Up to 10A
Mounting Type	DIN rail
Product designation	SIRIUS
Contact Material	Silver alloy
Contact Rating	Varies depending on the specific SIRIUS relay model (e.g., 6 A at 250 V AC, 10 A at 250 V AC)
Switching Voltage	Varies depending on the specific SIRIUS relay model (e.g., 250 V AC, 400 V AC)
Mechanical Life	Up to 10 million operations
Electrical Life	Up to 100, 000 operations
Operating Temperature	-25°C to +55°C
Protection Class	IP20
Size of relay base	Varies depending on the specific SIRIUS relay model