the time set with the Trip pulse time setting or the time the circuit breaker is in
the closed position, whichever is longer.
• If CB failure mode is set to "Both", TRRET is activated when either of the
"Breaker status" or "Current" mode condition is satisfied.
• If CB fail retrip mode is set to the "Without check" mode, TRRET is activated once
the timer 1 is activated without checking the current level. The TRRET output
remains active for a fixed time set with the Trip pulse time setting.
The activation of the BLOCK input or the CB_FAULT_AL output deactivates the TRRET
output.
POSCLOSE
I >
From Level detector 1
Timer 1 elapsed
From Timer 1
OR
AND
AND
CB fail retrip mode
”Without check”
CB fail retrip mode
”Current check”
CB failure mode ”Current”
CB failure mode ”Breaker
status”
CB failure mode ”Both”
AND
AND
AND
OR
OR
AND
TRRET
BLOCK
CB_FAULT_AL
From Timer 3
GUID-11B700C8-7CCF-41E4-89C7-741D4AC71887 V1 EN
Figure 391: Retrip logic
Backup trip logic
The backup trip logic provides the TRBU output which can be used to trip the upstream
backup circuit breaker when the main circuit breaker fails to clear the fault. The backup
trip logic is activated by the timer 2 module or timer-enabling signal from the start logic
module (rising edge of the PICKUP input detected), and simultaneously CB_FAULT_AL
is active. The operation of the backup logic depends on the CB failure mode setting.
• If the CB failure mode is set to "Current", the activation of TRBU depends on the CB
failure trip mode setting.
• If CB failure trip mode is set to "1 out of 3", the failure detection is based on any
of the phase currents exceeding the Current value setting. Once TRBU is
activated, it remains active for the time set with the Trip pulse time setting or
Section 5 1MAC059074-MB A
Protection related functions
778 615 series ANSI
Technical Manual
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