Siemens SIRIUS - Figure 2-7: Frequency Sensitivity of the N-Short-Circuit Releases

3RV1 circuit breakers
SIRIUS System Manual
2-12
GWA 4NEB 430 0999-02b
Frequency sensitivity of
the short-circuit
releases
The characteristics of the short-circuit releases apply to frequencies of 50/
60 Hz. For lower frequencies, such as 16
2
/
3
Hz, for higher frequencies up
to 400 Hz, and for direct current, appropriate correction factors have to be
taken into account.
The following characteristic curve illustrates the frequency sensitivity of the
short-circuit releases (calibrated to 12 times I
u
+20%):
Figure 2-7: Frequency sensitivity of the n-short-circuit releases
The increase in tripping current is approximately 30% for DC voltage.
Frequency converters
The thermal switch disconnectors do not have to be corrected when you
use frequency converters.
40
30
20
10
0
-10
-20
-30
050
100
200 250 300 350 400
Hz150
Tripping current
Change in %