ABB UniGear Digital, Engineering Manual

Page: 75 / 112

ENGINEERING ETHERNET
1VLG5 00007 E 63
High Availability Seamless Redundancy (HSR) network
The HSR ring applies the PRP principle of parallel operation to a single ring. For each message
sent, a node sends two frames, one over each port. Both frames circulate in opposite direc-
tions over the ring and every node forwards the frames it receives from one port to the other.
When the originating node receives a frame it sent, it discards the frame to avoid loops.
HSR redundancy is supported by Relion ® 615 (RED615 only via fiber optic interfaces), 620 and
640 series.
Figure 85: HSR network
HSR network with redboxes
Figure 86: HSR network with redboxes
The maximum number of IEDs in a HSR ring is 30. It is not recommended to configure more
than four SMV senders due to all information is sent into both directions in parallel.