GE Industrial Solutions Entellisys 4.0 System User Manual - Manual (Page 129)

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8
8 Reduced Energy Let-Thru Mode
The reduced energy let-thru mode (RELT) makes it easy for an operator to adjust the system to
previously defined fast protection settings by the touch of a button on the HMI screen. This
allows the system, under normal operating conditions, to be set at one level of settings and
provides an efficient way to adjust the settings to minimum trip settings (maximum level of
protection) and still maintain selectivity when personnel must be close to the equipment.
When Reduced Energy Let-Thru Mode is enabled, the advanced multi-point functions (Bus
Differential, Multi-Source Ground Fault, Ground Fault Tripping Priority and Zone Selective
Interlock) operate according to their Topology 0 (Reduced Energy 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.
Highlights
• Reduces potential arc flash energy - lowering the HRC category
• Easy to use - two mouse clicks to turn the mode on/off
• Programmable - RELT can be turned on and off via external sensors by changing RELT
status and control via FlexLogic
• Alarming - A Reduced Energy Let-Thru Mode alarm is available for visual and email
notification
Requirements
Reduced Energy Let-Thru Mode is always available when Advanced Multi-Point functions are
specified for the system.
Events
When Reduced Energy Let-Thru Mode is enabled/disabled, an event is displayed in the HMI
Events Viewer as follows:
• “ requested Multipoint RELT”
• “ requested to end Multipoint RELT”
• “User enabled Reduced Let-Thru Mode - Multipoint”
• “User ended Reduced Let-Thru Mode - Multipoint”
• “FlexLogic enabled Reduced LetThru Mode-Multipoint”
• “FlexLogic ended Reduced LetThru Mode-Multipoint”
Alarming
“Multipoint Reduced Let Thru On” Alarm is annunciated anytime either a user or FlexLogic
requests Reduced Energy Let Thru mode - regardless of the Reduced Energy status and will
re-arm every 8 hours (if acknowledged) until the system is returned to normal operation.
Criteria
Reduced Energy Let-Thru requires that at least one multipoint relay is optioned and operating.
Alternate relay settings must be set - see
Zones, buses, and topologies on page 101 .