Functions
6-1397SA6 Manual
C53000-G1176-C156-2
6.8 Earth Fault Protection Teleprotection Schemes (optional)
With the aid of the integrated comparison logic, the directional earth fault protection
according to Section 6.7 can be expanded to a directional comparison protection
scheme.
Teleprotection
Methods
One of the stages which must be directional and set Forward is used for the direc-
tional comparison. This stage can only trip if a fault is also seen in the forward direction
at the other line end. A release (unblock) signal or a block signal can be transmitted.
The following teleprotection schemes are differentiated:
Permissive (release) schemes:
• Directional comparison,
• Directional unblock scheme.
Blocking scheme:
• Blocking of the directional stage.
A further stage may be set as a non directional back up stage.
Signal
Transmission
Channels
For the signal transmission, one channel in each direction is required. For example,
fibre optic connections or voice frequency modulated high frequency channels via pilot
cables, power line carrier or microwave radio links can be used for this purpose. If the
same transmission channel as for the transmission by the distance protection (section
6.6) is used, the teleprotection scheme must also be the same!
Ifthedeviceisequippedwithanoptionalprotectiondatainterface,digital
communication lines can be used for signal processing; these include: Fibre optic
cables, communication networks or dedicated lines. The following teleprotection
scheme is suited for these kinds of transmission:
• Directional comparison
The signal transmission schemes are also suited to three terminal lines (teed feeders).
In this case, signal transmission channels are required from each of the three ends to
each of the others in both directions.
During disturbances in the receiver or on the transmission path, the teleprotection sup-
plement may be blocked via a binary input.
During disturbances on the transmission path, the teleprotection supplement may be
blocked. With conventional signal transmission schemes, the disturbance is signalled
by a binary input, with digital communication it is detected automatically by the
protection device.
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