2 Functions
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7SA522 Manual
C53000-G1176-C155-3
7SA522 allows also the transmission of phase-selective signals. This presents the ad-
vantage that single-pole automatic reclosure can be carried out even when two single-
phase faults occur on different lines in the system. Where the digital protection data
interface is used, the signal transmission is always phase segregated.
The signal transmission schemes are also suited to three terminal lines (teed feeders).
In this case, a signal is transmitted from each of the three ends to each of the others
in both directions. Phase segregated transmission is only possible for three terminal
line applications if digital communication channels are used.
During disturbances in the transmission path, the teleprotection supplement may be
blocked without affecting the normal time graded distance protection. The measuring
reach control (enable zone Z1B) can be obtained via the binary input ´!(QDEOH
$5]RQHVµ from an external reclosure device or from the internal automatic reclose
function. With conventional signal transmission schemes, the disturbance is signalled
by a binary input, with digital communication it is detected automatically by the protec-
tion device.
2.6.2 Method of Operation
Activation and
Deactivation
The teleprotection function can be switched on and off by means of the parameter
)&77HOHS'LV, via the system interface (if available) or via binary input (if
this is allocated). The switched state is saved internally (refer to Figure 2-47) and
secured against loss of auxiliary supply. It is only possible to switch on from the source
where previously it had been switched off from. To be active, it is necessary that the
function is switched on from all three switching sources.
Figure 2-47 Activation and deactivation of the signal transmission logic
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