Directional Earth Fault Command Protection - Toshiba GRL100-701B Instruction Manual

2.4.1

Directional Earth Fault Command Protection

High-speed directional earth fault command protection is provided using the forward looking
directional earth fault element DEFF and reverse looking directional earth fault element DEFR.
The signaling channel of DEF command protection can be shared with or separated from distance
protection by the scheme switch [CH-DEF].
Figure 2.4.1.1 shows the scheme logic for the DEF command protection.
The DEF command protections are applied in combination with the distance command protection
POP, UOP, BOP and PUP and enabled when the scheme switch [CRSCM] is set to "POP",
"UOP", "BOP" or "PUP". These protections are called as the DEF POP, DEF UOP, DEF BOP and
DEF PUP hereafter. The POP, UOP or BOP schemes can be selected as a common scheme.
However, in the DEF PUP, distance protection takes the PUP scheme but DEF command
protection takes the POP scheme and signaling channels of distance and DEF command
protections are always separated (CH1: distance, CH2: DEF, see Section 2.3.2.9.).
The DEF command protection can select fast tripping or delayed tripping by a timer setting.
Delayed tripping is used when it is desired to give priority to distance protection.
The DEF command protection is blocked during a single-phase autoreclose period by the distance
protection (CB-DISCR=1). The signal CB-DISCR is generated with the binary input signals (PLC
signals) of circuit breaker auxiliary contact (refer to Section 3.2.1).
The DEF command protection provides the phase selection logic for single-phase tripping. The
details are shown in Figure 2.4.1.2. The current change detection element separated (OCD1) is
used as the phase selection element. In addition, it is possible to input the output of external phase
selection relay in PLC input DEF_PHSEL-A, DEF_PHSEL-B and DEF_PHSEL-C.
Phase selection
DEFF
Logic for DEF
NON VTF
CB-DISCR
DEFR
DEFF
605
OCD1 - A
606
OCD1 - B
607
OCD1 - C
DEF_PHSEL-A
1988
DEF_PHSEL-B
1989
DEF_PHSEL-C
1990
&
&
Figure 2.4.1.1 DEF Command Protection
1
S
≥1
R
S
≥1
R
S
≥1
R
Figure 2.4.1.2 Phase Selection Logic for DEFF
 77 
TDEFC
t 0
0 – 300ms
[CRSCM]
TDERC
t 0
"POP"
"UOP"
0 – 300ms
"BOP"
"PUP"
≥1
≥1
≥1
≥1
1
6 F 2 S 0 8 5 0
775 DEFFCR
DEFRY
776 DEFRCR
&
DEFFCR-A
&
DEFFCR-B
&
DEFFCR-C