Siemens SENTRON VL Series

Zone Selective Interlocking
5.1 ZSI
3WL/3VL circuit breakers with communication capability - PROFIBUS
108 System Manual, 03/2011, A5E01051353-02
5.1.5 Operating principle
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● Every circuit breaker is equipped with a ZSI module
● The ZSI modules are linked to each other via twisted-pair connections
● The ZSI output (ZSI OUT)
① is connected with the ZSI input (ZSI IN) ②
● ZSI modules in one grading level are switched in parallel (see examples)
● Coupling switches can be integrated (see examples)
● Medium voltage can be integrated (see examples)
● Extremely simple parameterization of the ZSI modules
5.1.6 Course over time
5.1.6.1 Condition ZSI = ON and presence of a short-circuit (S)
1. The overcurrent releases detect a short-circuit (S) and start the predefined delay times t
sd
2. Each circuit breaker that detects the short-circuit informs the higher-level breakers of the
detected short-circuit (ZSI_OUT ⇒ ZSI_IN ⇒ ZSI_OUT ...)
3. Each circuit breaker that receives no information (ZSI IN) from subordinate grading levels
and detects the short-circuit forces a short-circuit trip after 50 ms (t
ZSI
).
4. Otherwise, a short-circuit trip occurs at the end of the delay time t
sd
Result: The ZSI module switches off the short-circuit after 50 ms in the next level to the fault.