GE Industrial Solutions Entellisys System User Manual - Manual (Page 111)

Setup 111
8
8 Reduced Let-Thru Mode
Entellisys Reduced Let-Thru Mode settings, used in conjunction with Bus Differential protection,
make it easy to set the System to minimum trip settings (maximum level of protection) when
personnel must be close to the gear.
When Reduced Let-Thru Mode is enabled, the advanced multi-point functions (Bus Differential,
Multi-Source Ground Fault, and Zone Selective Interlock) operate according to their Topology 0
(Reduced Let-Thru Mode) Pickup and Delay settings, regardless of the state of topology circuit
breakers. The Topology 0 settings are user-selectable, but are typically set to values that
provide the maximum level of protection; i.e., when a fault is detected, Entellisys will trip all
circuit breakers that could feed the fault with the minimum delay.
NOTE: Reduced Let-Thru Mode only applies when the Advanced Multi-Point functions are
enabled. This includes Bus Differential relay, Multi-Source Ground Fault relay, and Zone Selective
Interlock (ZSI) function.
8.1 Setup
To enable Reduced Let-Thru Mode
1. On the Main Menu, click Reduced Let-Thru Mode.
2. Select Enabled, and then click OK.
To disable, clear the same check box and click OK (see Figure 8-1).
Figure 8-1 Enabling Reduced Let-Thru Mode