Siemens SIRIUS System Manual

3RW3 semiconductor motor control unit
SIRIUS System Manual
8-6
GWA 4NEB 430 0999-02b
8.2.1 Physical principles
Starting current
Three-phase current asynchronous motors have a high inrush current I
(star-
ting)
. This inrush current can be between three and fifteen times as high as
the rated operational current, depending on the type of motor. A figure bet-
ween seven and eight times the rated operational current can be postulated
as typical.
Figure 8-1: Typical current and torque curve of a three-phase asynchronous motor
Important
This starting current must be taken into consideration in the design of the
supply network, among other things by adapting the supply (high heat deve-
lopment) and the fusing (inadvertent tripping of the fuses).
Reducing the starting
current
There are various ways of reducing the starting current:
• By star-delta starter
• By frequency converter
• By soft starter
I
starting
I
0 (no-load)
I
I
rated
n
rated
n
syn
n
M
n
M
starting
M
saddle
M
motor
M
cusp
M
motor
M
rated
n
rated
n
syn
M
accel
M
load
M
load

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