Siemens siprotec 7SA522 User Manual

2 Functions
140
7SA522 Manual
C53000-G1176-C155-3
Figure 2-57 Unblock logic
2.6.7 Directional Blocking Scheme
The following scheme is suited for conventional transmission media.
Principle In the case of the blocking scheme, the transmission channel is used to send a block
signal from one line end to the other. The signal may be sent directly after fault incep-
tion (jump detector above dotted line in Figure 2-58), and stopped immediately, as
soon as the distance protection detects a fault in the forward direction, alternatively the
signal is only sent when the distance protection detects the fault in the reverse direc-
tion. It is stopped immediately as soon as the distance protection detects a fault in
forward direction. Tripping is possible with this scheme even if no signal is received
from the opposite line end. It is therefore mainly used for long lines when the signal
must be transmitted across the protected feeder by means of power line carrier (PLC)

Siemens siprotec 7SA522 Specifications

General

Brand	Siemens
Model	siprotec 7SA522
Category	Protection Device
Language	English