Transmission Line Current Differential Protection

[microaid]

Is anyone familiar with the use of devices (such as SDH) to introduce delays into the transmission time for data associated with current differential protection to synchronise this data when different communication paths are being used by the relays at each end of the protected line (eg when there has been a failure of the normal comms. path and the data it is routed via different/indirect paths)?
PS It sounds to me that it would be simplier to just use the backup Distance element that is available in many current differential models.

 

[DiscoP]

The P545 & P546 from Areva is suitable for this application - there are probably others too. Check out the literature on their webiste -

http://www.areva-td.com