Toshiba GRZ100 B Series, Instruction Manual

Page: 63 / 447

⎯
62
⎯
6 F 2 S 0 8 4 6
When the PUP+DEF scheme logic is selected, the DEF scheme logic is constructed same as the
DEF POP scheme logic in Figure 2.4.4.3.
The signal transmitted is a trip permission signal for the POP and a trip block signal for the UOP.
In the event of an internal fault, the POP transmits a signal, while the UOP stops transmission. In
Figure 2.4.4.3, a signal is transmitted when CS becomes 1, and when the signal is received
CR-DEF becomes 1. If the PLC signal PSCM_TCHDEN is established, the delayed pick-up timer
TCHD is provided.
When the DEFF operates, CS becomes 1 for the POP and a signal (that is, a trip permission signal)
is transmitted. For the UOP, CS becomes 0 and transmission of the signal (that is, a trip block
signal) is stopped.
When a signal is received in the POP, or no signal is received in the UOP, tripping is executed on
condition that the DEFF has operated. In order to assure tripping of the remote terminal,
transmission of a trip permission signal or stoppage of a trip block signal continues for the TSBCT
setting time even after the DEFF reset.
The DEFR is used for the current reversal logic in the same manner as reverse looking Z4 in the
distance protection (for the current reversal, refer to Section 2.4.3.6).
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 lines 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.