GE Industrial Solutions Entellisys 5.0 User Manual - Manual (Page 136)

Multi-point functions 136
7
7.5 Downstream Zone Selective Interlocking
For Entellisys feeders, downstream Zone Selective Interlocking (ZSI) is available to further
improve the selectivity with a wide range of equipment. When a protection device with ZSI
output is enabled and physically wired to the messenger, the Messenger will respond to a
restraint signal and will restrain Short Time and IOC to the “IOC ZSI Restrain Time” and “ST Time
Delay” settings.
If Entellisys ZSI option is available, the ZSI restraint signal will propagate to breakers up stream
and restrain Short Time Overcurrent as defined by the Entellisys ZSI Zone configuration. (
See
section 7.4 Zone Selective Interlock on page 129)
NOTE: Entellisys Ground Fault is not restrained during a downstream ZSI signal and thus must
be adjusted above downstream equipment to avoid nuisance tripping.
Entellisys Downstream ZSI is applicable to the ZSI output from GE MicroVersa Trip, Entelligaurd
TU and Micro Entelligaurd trip units.
7.5.1 Installation
Entellisys expects a reverse logic dry contact input from a downstream overcurrent device. The
Entellisys messenger will wait for an “Arming signal” or closed set of contacts to detect the
presence of a downstream device and will then restrain on the negative transition - from closed
to open.
Entellisys 5.0 ships with ZSI Input for all Entellisys Messengers wired out to terminal blocks.
Interposing relays and wiring to be supplied by others.
Figure 7-12 Typical Downstream ZSI wiring diagram
ZSI inputs from downstream trip units shall be wired to solid state control relays with normally
closed contacts. Relays shall be selected to work with the downstream trip units.