GE Industrial Solutions Entellisys 5.0 User Manual - Manual (Page 137)

Downstream Zone Selective Interlocking 137
7
Entellisys feeder breakers that supply more than one downstream breaker may use multiple ZSI
interface relays wired in series.
Downstream ZSI “Armed”
The Entellisys Messenger will consider a ZSI downstream device “Armed” when the ZSI input is
shorted to common through an interposing relay. The Armed status is stored in volatile memory
will re-arm if control power on the messenger is cycled.
7.5.2 Setup
Downstream ZSI restraint settings are configured in the “Downstream External ZSI Input”
control group located in the Overcurrent Protection settings screen of the respective breaker.
IOC Restraint
When the Instantaneous Overcurrent type is set to “Adjustable Selective IOC”, the “IOC ZSI
Restrain Time” will be sent to the messenger and restrain the IOC algorithm by the selected
number of half cycles ONLY when both conditions are true:
• A downstream device is detected (the input circuit is wired and completed through the
normally closed interposing relay)
• A negative transition is detected (from closed to open)
When the restraint signal is active, IOC ZSI Restraint Time and ST Delay Band ZSI Restraint
settings will be active.
NOTE: At no time will the downstream ZSI restraint be enabled if the system was not previously
“Armed.”