Ashida ADR233B - CBF Operating Logic (CB FAIL)

ADR233B
Doc ID : ADR233B/IM/01
Ref ID : ADR233B/IM/PS
Rev No. : 05
Page No. : 149 of 479
protection (CBF) will operate. CBF operation can be use to operate back-trip upstream circuit
breakers to ensure that the fault is isolated correctly.
4.16.1 CBF Operating Logic (CB FAIL)
The CBF Operating function provided for “Breaker Failure” menu. The CB failure protection logic
is performing as follows.
The “t50BF Delay” timer is initiated when a trip order is issued through the internal protection trip
or by an External “50BF Ext” digital input signal, the relay issues “50BF T” signal when the
“t50BF Delay” is expired.
The following four ways to reset 50BF Protection trip (50BF Reset = 1)
• I<: The 50BF trip will reset when the relevant phase current is less than minimum set
current
• CB Open + I<: The 50BF trip will reset when both conditions are satisfied, first condition is
when the relevant phase current is less than minimum set current and second condition is
CB must be opened (i.e. 52B status is active)
• Prot Reset + I<: The 50BF trip will reset when both conditions are satisfied, first condition is
Protection reset and second condition is the relevant phase current is less than minimum
set current
• CB Open: CB must be opened (i.e. 52B status is active)
Following diagram explains the function of CBF logic
Protection
Trip
50 BF Ext = 1
&
50BF Delay
50BF
Trip
50BF Enable
= Enabled
If I in all phases is
less than 50BF_I
52B
&
50BF Reset
S
Q
R
Protection Reset
&
Figure 27: CBF Operation and Reset Logic