Siemens SIPROTEC 7SD600 System Manual page 46

Numerical line differential protection SIPROTEC 7SD600 V3.0
The function "Tripping by remote station" with the
parameters "13 TR.R" (off-on) "13 DEL" (delay time)
is provided for this purpose. This function can be ex
ternally blocked (marshalling function ">Rec.bl", Fno.
3333).
Remote tripping must not be confused with the inter
trip function which is an integral part of the differen
tial protection function (see section 4.4.2).
Only one pilot wire pair and one carrier frequency
(2000 Hz) are available for pilot wire monitoring, trans
fer tripping and remote tripping. For this reason it is
essential to differentiate via impulse code, whether a
pilot wire monitoring signal or a trip signal is to be
transmitted. Pilot wire monitoring is halted during
Siemens AG January 1999
Method of operation
System manual Order no. E50417-G1176-C069-A1
transmission of a trip signal (transfer tripping or re
mote tripping).
At the receiving end, no distinction is made between
transfer tripping or remote tripping, as the impulse
code is the same. The reaction of the device is also
the same: tripping via receiving signal.
The remote tripping should only be used in one direc
tion, because in the coincidental event of simulta
neous transmission in both directions, overlapping of
the two signals would occur. In this case, the condi
tions for the impulse code would no longer be fulfil
led: the received signals would not initialize a tripping.
Figure 4.9 shows the logic diagram of the functions
relating to the pilot wire monitoring.
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