GE Industrial Solutions Entellisys System User Manual - Manual (Page 116)

Reduced Let-Thru Mode 116
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Figure 8-5 Reduced Let-Thru Mode settings for Zone Selective Interlock
8.2 Troubleshooting
When Reduced Let-Thru Mode is enabled, multi-point relays (Bus Differential and MSGF) are
not running in the system
• Verify that for topology 0 in all zones both Bus Differential and Multi-Source Ground-Fault
(Trip & Alarm-Only) relays are enabled.
• Verify that all concerned zone member circuit breakers are commissioned.
• Verify that all concerned zone member circuit breakers are communicating with the CPU.
• Verify from the one-line diagram that no zone member circuit breaker is sensing current that
exceeds 10 times its CT rating.
When Reduced Let-Thru Mode is enabled, ZSI is not working
• Verify that for topology 0 in all zones (ZSI-Short Time or ZSI-Ground Fault) the ZSI function is
enabled.
• Verify that for topology 0 in all zones at least one feeder member's tier number is non-zero.