Toshiba GR200 Series Instruction Manual page 214

through the transmission line because that the transmission line includes a fault; the fault
may reduce the power of the signal and then PUP and POP may fail to operate. Unblocking
overreach protection (UOP) is introduced in order to negate this issue.
We can regard a transmitted signal as a trip block signal; and the trip block signal is
transmitted continuously except for the fault conditions. When the forward overreaching
element operates, signal transmission is stopped; hence, a trip block signal is not reached at
an opposite terminal. Consequently, the opposite terminal is allowed to trip; and CB tripping
is carried out when the forward overreaching element on its own operates.
ZCSF/ZCGF elements are used for the forward overreaching element. On the other hand,
ZCSR/ZCGR elements are used for the reverse looking element.
In UOP, the signal is required to send except for the occurrence of internal faults.
Therefore, a failure to operate or false operation due to attenuation of the signal will be
removed even if the power line carrier is used to exchange operation information.
Operation of echo (ECHO) and week infeed trip (WKIT)
(i)
UOP can have the functions of ECHO and WKIT, as well as POP. To operate these function,
user should set [Dis-ECHO] On or [Dis-WIKT] On. (For more information of ECHO and WKIT,
see section 2.12.5)
Countermeasure of current reversal (CRL)
(ii)
UOP has the countermeasure of current reversal, as well as POP. (For more information of
CRL, see section 2.12.6)
Delay of trip block signal
(iii)
As similar to POP, UOP has setting [TSBCT-dis] not to send the trip block signal even after
the local terminal issues a trip signal.
Scheme logic
(iv)
Figure 2.12-3 and Figure 2.12-4 also show UOP scheme logic. In UOP, trip block signals
(DISCAR-S: used for the external carrier communication) and (INT.DISCAR-S-*: used for the
integral carrier communication) are observed when the logic level in UOP is equal to "1".
Conversely, a trip block signal is not observed when the logic level is equal to "0".
UOP does not send a trip block signal when one of the following conditions are observed:
The forward overreaching element operates and the current reversal is not occurred.
✓
When On is set for scheme switch [Dis-ECHO], CB is open and the trip block signal
✓
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6F2S1914 (0.49)
GRL200 (Soft 033 & 037)