2.6 Teleprotection for distance protection
129
7SA522 Manual
C53000-G1176-C155-3
2.6.3 Permissive Underreach Transfer Trip with Zone Acceleration Z1B (PUTT)
The following procedure is suited for both conventional and digital transmission media.
Principle Figure 2-48 shows the operation scheme with zone acceleration for this permissive
underreach transfer trip scheme. In the case of a fault inside zone Z1, the transfer trip
signal is sent to the opposite line end. The signal received there causes tripping if the
fault is detected inside the zone Z1B in the set direction. The transmit signal can be
prolonged by T
S
(settable at address 6HQG3URORQJ), to compensate for pos-
sible differences in the pick-up time at the two line ends. The distance protection is set
such that the first zone reaches up to approximately 85% of the line length, the over-
reaching zone however is set to reach beyond the opposite substation (approximately
120% of the line length). On three terminal lines Z1 is also set to approximately 85%
of the shorter line section, but at least beyond the tee off point. Z1B must securely
reach beyond the longer line section, even when additional infeed is possible via the
tee point. For this procedure, transmission via a protection data interface (if provided)
is offered.
In protective relays equipped with a protection data interface, address
7HOHSURW'LVW allows to set 6,*1$/Y3URW,QW. At address )&7
7HOHS'LV 3877=% can be set.
Figure 2-48 Operation scheme of the permissive underreach transfer trip method via Z1B
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