63
6
F
2
S
0
8
3
4
When operation of the DEFR and no-operation of the DEFF continue for 20 ms or more, even if
the DEFF operates or the DEFR is reset later, tripping of the local terminal or transmission of the
trip permission signal is blocked for the TREBK setting time.
The POP or UOP can be set for instantaneous operation or delayed operation by setting on-delay
timer TDEFF and TDEFR.
The DEF command protection is provided with an echo function and weak infeed trip function.
Both functions are used for lined with weak infeed terminals.
The echo function allows fast tripping of the terminal on which the DEFF has operated when
applied to a line with an open terminal or a weak infeed earth fault current terminal. The scheme
logic is shown in Figure 2.4.4.4.
With the POP, when a trip permission signal is received (R1-CR-DEF = 1) if neither the forward
looking DEFF nor the reverse looking DEFR operates, the echo function sends back the received
signal to the remote terminal. With the UOP, when reception of a blocking signal is stopped
(R1-CR-DEF = 0), if the DEFF and DEFR do not operate, the echo function stops transmission of
the blocking signal likewise. When the circuit breaker is open, the echo function also sends back
the trip permission signal or stops transmission of the blocking signal.
Once the DEFF or the DEFR operates, transmission of the echo signal is inhibited for 250 ms by
delayed drop-off timer T1 even after they are reset.
In order to prevent any spurious echo signal from looping round between terminals in a healthy
state, the echo signal is restricted to last 200 ms by delayed pick-up timer T2.
The echo function can be disabled by the scheme switch [ECHO] and the PLC signal
ECHO_BLOCK.
When a signaling channel is shared by the distance protection and DEF protection, it is necessary
to unite the scheme logic of both echo functions so that the echo function may not be picked up in
the event of an external fault. The echo function at this time is blocked by Z2 (or Z3) and Z4
indicated by a dotted line in Figure 2.4.4.4.
"ON"
&
&
≥
1
200ms
(+)
t
0
Z3
Z2
Z4
T2
T1
250ms
0 t
50ms
0
t
[ZONESEL]
"Z3"
"Z2"
[ECHO]
1
CB-OR
≥
1
R1-CR-DEF(POP)
TECCB
0.00 - 200.00s
t 0
DEFFCR
DEFRY
1
R1-CR-DEF(UOP)
(UOP)
(POP)
CS
CS
1
CS (Carrier send) signal
Signal No. Signal name
225: EXT_CAR-S for Distance and DEF
command protection (CH1)
338: EXT_DEFCAR
-
S for DEF command
protection (CH2)
R1-CR-DEF: Trip permission signal from the remote terminal.
Signal No. Signal name Description
1568: EXT_CAR.R1-1 Trip carrier signal from
remote terminal
1569: EXT_CAR.R1-2 Guard/And carrier signal
from remote terminal
&
&
ECHO1_DEF-R1
1
ECHO_BLOCK
1840
&
Figure 2.4.4.4 Echo Function in DEF POP and DEF UOP Scheme Logic
Figure 2.4.4.5 shows the scheme logic of the weak infeed trip function. Weak infeed tripping is
executed on condition that a trip permission signal has been received (ECHO1_DEF-R1=1) for
the POP, the undervoltage element UVL (UVLS or UVLG) operates.
The undervoltage element responds to three phase-to-phase voltages and three phase-to-ground
voltages. The undervoltage element prevents false weak infeed tripping due to spurious operation
of the channel.
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Summary of Contents for GRZ100-211B
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