Earth Fault Protection Teleprotection Schemes - Siemens siprotec 7SA6 User Manual

6.6

Earth Fault Protection Teleprotection Schemes

Teleprotection
Methods
Signal
Transmission
Channels
7SA6 Manual
C53000-G1176-C133-1
With the aid of the integrated comparison logic, the directional earth fault protection
according to Section 6.5 can be expanded to a directional comparison protection
scheme.
One of the stages which must be directional and set )RUZDUG is used for the
directional 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.
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
6.4) is used, the teleprotection scheme must also be the same!
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
the each of the others in both directions.
During disturbances in the receiver or on the transmission path, the teleprotection
supplement may be blocked via a binary input.
Functions
6-121