hager hw+ User Manual

596LE008146B
Protection functions
4.7 Zone Selective Interlocking function (ZSI)
The Zone Selective Interlocking (ZSI) function is designed to limit the electro-dynamic
constraints on the installation in case of a short circuit fault or earth fault.
The devices, conductors, busbar trunking and busbars can thus benefit from this limitation.
It reduces the time taken to clear the electrical fault while maintaining the selectivity and
coordination provided by the protection settings.
The installed circuit breakers are linked together by cable to determine which circuit breaker
should trip first. If an electrical fault appears between two linked circuit breakers connected
together by the ZSI function, the downstream circuit breaker is unable to clear it. Thanks to
zone selectivity, the circuit breaker upstream of the fault trips without waiting till the end of its
time delay.
For zone selectivity to work correctly, the ZSI terminals of all circuit breakers must be
connected together among themselves. The tripping time delay of each circuit breaker must
be adjusted according to the chronometric sensitivity desired and the ZSI function must be
activated (only on circuit breakers linked to their downstream circuit breakers).
The ZSI function applies to the Short Time Delay protection (ZSI STD) and the Earth Fault
protection (ZSI GF).
Here are two examples to explain the functioning.
STD2
GF2
Cmn2
STD1
GF1
Cmn1
STD2
GF2
Cmn2
STD1
GF1
Cmn1
STD2
GF2
Cmn2
STD1
GF1
Cmn1
ZSI
2
ZSI
1
Q2
Q1
Q4
Q3
a)
b)
h3+ Energy
hw+
hw+
hw+
Zone selectivity: Example
White
Green
Brown
First, circuit breakers Q1, Q2, Q3, Q4 are set to their respective thresholds enabling the
expected time selectivity to be activated. The ZSI function must be activated only on the Q1
and Q2 circuit breakers.
Fault example a):
- If a fault occurs at point a), the Q1 and Q2 circuit breakers detect the electrical fault. Thanks
to the ZSI cabling (in blue), the Q1 circuit breaker receives a signal from Q2 and remains
closed to allow the Q2 circuit breaker to eliminate the fault. The Q2 circuit breaker does
not receive a signal either from Q3 or Q4. It opens immediately, despite the previously set
tripping time delay.

hager hw+ Specifications

General

Brand	hager
Model	hw+
Category	Circuit breakers
Language	English