Siemens SIRIUS 3RW40, Manual

Page: 18 / 212

Product description
3.3 Functional principle of the SIRIUS 3RW30 and 3RW40 soft starters
SIRIUS 3RW30 / 3RW40
18
Manual, 01/2010, 535 1995-02 DS01
Example
The diagrams below show the starting current and torque characteristics for a three-phase
induction motor in combination with a soft starter:
Figure 3-3 Reduced current characteristic of a three-phase induction motor during starting with a
SIRIUS 3RW30 or 3RW40 soft starter
SIEMENS 1LG4253AA motor (55 kW)
Rated data at 400 V
P
e
: 55 kW
I
e
: 100 A
I
direct starting
: Approx. 700 A
M
e
:
355 Nm ; e.g.: M
e
= 9.55 x 55 kW x
n
e
: 1480 rpm
M
direct starting
: Approx. 700 Nm
Set starting voltage: 50 % (½ of mains voltage)
=> I
starting
½ of direct starting current (approx. 350 A)
=> M
starting
¼ of direct starting torque (approx. 175 Nm)
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,
,
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,
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,
1RP
Q
1RP
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Q