Measuring Accuracy; 3Wl Breaker Measuring Accuracy - Siemens SENTRON VL Series System Manual

3WL air circuit breakers

3.6 Measuring accuracy

Advantages
Zone Selective Interlocking (ZSI) offers full selectivity with the extremely short delay time t
= 50 ms, irrespective of the number of grading levels and the location of the short-circuit in
the distribution system. The benefit is all the greater the higher the number of grading levels
in large systems, and the longer the resulting delay times for standard time grading.
By shortening the break time, ZSI significantly reduces stress and damage in the switchgear
in the event of a short-circuit.
Figure 3-21
You can find more detailed information on this in Chapter "Zone Selective Interlocking
(Page 105)
3.6 Measuring accuracy
3.6.1

3WL breaker measuring accuracy

The measuring accuracy depends on the circuit breaker components.
The accuracy (when ordering the switch + trip unit + metering function PLUS direct) refers to
the full-scale value.
The full-scale value refers to the maximum rated current I
the size of the rating plug and the rated current I
82
ZSI module
n max
set by it.
n
3WL/3VL circuit breakers with communication capability - PROFIBUS
System Manual, 03/2011, A5E01051353-02
of the breaker, regardless of
ZSI