Toshiba GRZ100 B Series, Инструкция по эксплуатации, Страница: 54 / 447

⎯
53
⎯
6 F 2 S 0 8 4 6
Element Setting Remarks
Z4BG
θ
(*3) Interlinked with ZBG
θ
Angle of Z4 directional element
BRRG
θ Fixed to 75° Angle of reverse right blinder BRRG
BRLG Interlinked with BRRG Reverse left blinder
BRLG
θ
Interlinked with BFLG
θ
Angle of reverse left blinder BRLG
(*1) Ohmic values shown in the parentheses are in the case of 1 A rating. Other ohmic values are in the
case of 5 A rating.
(*2) Valid only when mho-based characteristic is selected by ZS-C and ZG-C.
(*3) Valid only when quadrilateral characteristic is selected by ZS-C and ZG-C.
The reverse looking elements Z4 (G,S), BRR (G,S) and BRL (G,S) must always operate for
reverse faults for which the forward overreaching element of the remote end operates. The
following setting coordination is required.
When zone 2 is selected as the forward-looking element,
Z4 setting = 1.2
×
(Zone 3 setting at remote end)
or
Z4 setting =
α ×
(Zone 2 setting at remote end)
Note:
α
should be determined in consideration of the extension of zone 2 by zero-sequence
compensation.
When zone 3 is selected,
Z4 setting = 1.2
×
(Zone 3 setting at remote end)
In both cases,
BRR setting = 1.2
×
(BFR setting at remote end)
The delayed pick-up timer TCHD is set as follows taking into account the transmission delay time
of the blocking signal and a safety margin of 5 ms.
TCHD setting = maximum signal transmission delay time(*) + 5ms
(*) includes delay time of binary output and binary input for the blocking signal.
2.4.3.5 Protection for Weak Infeed Terminal
The POP and UOP are provided with an echo function and weak infeed trip function. Both
functions are used for lines with weak infeed terminals.
Figure 2.4.3.5 shows the scheme logic for the echo function.
With the POP, when a trip permission signal is received (R1-CR=1) if neither forward
overreaching zone 2 or zone 3 nor reverse looking Z4 have operated, 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=0) if neither forward overreaching zone 2 (or zone 3) nor reverse looking Z4
have operated, the echo function stops sending the blocking signal to the remote terminal. When
the circuit breaker is open (CB-OR = 0), too, the echo function sends back the trip permission
signal or stops sending the blocking signal. Timer TECCB is used to set the time from CB opened
to the echo logic enabled.
The terminal on which the forward overreaching element has operated can be tripped at high speed
by this echoed signal.
Once the forward overreaching element or reverse looking element have operated, transmission of
the echo signal is inhibited for 250 ms by delayed drop-off timer T1 even after they have reset.
In order to prevent any spurious echo signal from looping round between the terminals in a healthy
state, the echo signal is restricted to last for 200 ms by delayed pickup timer T2.