controller unit 3BSE081636R1

controller unit 3BSE081636R1

controller unit 3BSE081636R1

Blocking scheme In blocking scheme a reverse looking zone is used to send a block signal to remote end to block an overreaching zone. Since the scheme is sending the blocking signal during conditions where the protected line is healthy, it is common to use the line itself as communication media (PLC).

The scheme can be used on all types of line length. The blocking scheme is very dependable because it will operate for faults anywhere on the protected line if the communication channel is out of service.

Conversely, it is less secure than permissive schemes because it will trip for external faults within the reach of the tripping function if the communication channel is out of service. Inadequate speed or dependability can cause spurious tripping for external faults. Inadequate security can cause delayed tripping for internal faults. To secure that the carrier send signal will arrive before the zone used in the communication scheme will trip, the trip is released first after the time delay tCoord has elapsed.

The setting of tCoord must be set longer than the maximum transmission time of the channel. A security margin of at least 10 ms should be considered. The timer tSendMin for prolonging the carrier send signal is proposed to set to zero in blocking schemes.