Zone Selectivity – More Precise and Faster Shutdown

Zone selectivity (ZSI), precise and fast shutdown of switchgear systems

Zone selectivity: The switches are interconnected by a signal line. In the event of a fault, the signal line ensures that only the switch immediately upstream of the fault, which is feeding the short-circuit, is shutdown without delay.

In contrast to time selectivity, a non-delayed shutdown is triggered here at every point in the radial network. Thus, the energy that is developed (I2xt) and the resulting thermal and dynamic system loading is reduced to a minimum. Zone selectivity ensures that only the switches immediately upstream of the fault are shutdown. Thus it allows the rest of the non-faulty system to remain operational, and the downtime is reduced to a minimum.