3WL air circuit breakers
3.6 Measuring accuracy
3WL/3VL circuit breakers with communication capability - PROFIBUS
82
System Manual, 03/2011, A5E01051353-02
Advantages
Zone Selective Interlocking (ZSI) offers full selectivity with the extremely short delay time t
ZSI
= 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.
2))
6
*
6*
7(67
Figure 3-21 ZSI module
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 trip unit + metering function PLUS direct) refers to
the full-scale value.
The full-scale value refers to the maximum rated current I
n max
of the breaker, regardless of
the size of the rating plug and the rated current I
n
set by it.
