Toshiba GR200 Series Instruction Manual page 132

Operation of EFP Transfer-trip (Mode 2)
(ii)
Figure 2.5-3 shows the CT used in the bus-bar protection with the CB (CB-A) located at the
busbar side of the CT; the bus-bar will operate despite CB-A being open. If a fault occurs
between the CT and CB-A, the DIF relay may operate because the fault occurs in its zone of
protection. In this case, the DIF relay is not required to operate
achieved by tripped the CB at the remote-terminal. Therefore, a issued Transfer-trip signal
shall be forwarded to CB-D at the remote-terminal, following the operation of OCEFP_CH*
relay and the examination of the open state of CB-A being complete. To the operation in Mode2,
set On-TR for the settings [EFP-EN_CH*] in respective CHs.
Remote
end
CB-D
Figure 2.5-3 Fault occurrence and current flow before tripping
Remote
end
CB-D
EFP Transfer-trip
Figure 2.5-4 Tripping CB-D by EFP Transfer-trip
Note: The CH X can treat the current (I X ) as zero while CB-A is open. Such a function is
1
termed "Zero-ampere current-control". The operation of the discriminating-zone-
protection in DIF can be blocked using "Zero-ampere current-control" when a fault
occurs. However, the operation of the check-zone-protection cannot be blocked
because the check-zone-protection does not have such a function. That is, the
check-zone-protection will still operate when a fault occurs but will not result in
tripping of the CB because the discriminating zone protection is blocked using the
"zero-ampere control" function. Hence, the user should take note that unwanted
tripping may occur if only the check-zone-protection is engaged in the DIF relay.
Note: The operation of the DIF relay results in tripping of CB-B and CBC in Figure
2
2.5-3.
Setting items Mode / range
On-Zone
EFP-EN_CH*
I X
CT
Line
CH X
Line
CT
CH X
Table 2.5-2 EFP setting switches
Unit
Off Off mode: Blocking EFP operation
– Mode1: Enabling Zone trip in each CH
On-TR Mode2: Enabling Transfer trip in each CH
- 118 -
1
; fault clearance should be
2
Busbar Busbar
Zone A Zone B
Fault
CB-A
CB-B
CBC
Busbar Busbar
Zone A Zone B
Fault
CB-A
CB-B
CBC
Contents
Centralized GRB200
6F2S1931 (0.20)
Default
Off
(Soft: 030, 031, 032, 033, 034)