15.10
SEL-400 Series Relays Instruction Manual Date Code 20171006
Communications Interfaces
Ethernet Communications
Using Redundant Ethernet Ports
Relays may have as many as four Ethernet ports, which work together in pairs: A
and B, C and D. One pair of ports are for TDP/I/P or UDP/IP Ethernet communi-
cations, including FTP, TELNET, DNP3 LAN/WAN, etc., and IEC 61850 GOOSE.
You can configure these ports for redundant network architectures, or force the
relay to use a single Ethernet port for these protocols. If the relay has four ports,
the second pair of ports can be used for relay specific functionality. PTP is only
available on ports A and B.
Redundant Ethernet Network Using FAILOVER Mode
Make the following settings in Port 5 to configure the relay for FAILOVER mode.
➤ NETMODE := FAILOVER
➤ FTIME := desired time-out for the active port before failover to the
backup port
➤ NETPORT := the preferred primary network interface (C for Port 5C,
D for Port 5D)
Use the internal failover switch to connect the relay to redundant networks as
shown in Figure 15.5.
On startup, the relay communicates using the primary network interface selected
by the NETPORT setting. If the relay detects a link failure on the primary inter-
face, it asserts the LNKFAIL Relay Word bit. If the link status on the standby
interface is healthy, the relay activates the standby network interface after time
FTIME. If the link status on the primary interface returns to normal before time
FTIME, the failover timer resets and operation continues on the primary network
interface.
After failover, while communicating via the standby interface, if the relay detects
a link failure on the standby interface and the link status on the primary interface
is healthy, the relay activates the primary network interface after time FTIME.
The choice of active port is reevaluated after settings change, and after relay restart.
In either case, if the relay detects a link failure on the interface on which it is cur-
rently communicating, it asserts the LNKFAIL Relay Word bit. In relays that
support process bus functionality, FAILOVER is the only supported mode. If the
relay detects a failure on its current process bus interface, it will assert the LNK-
Figure 15.5 Failover Network Topology
Relay
Relay
Relay
Network
SEL-2725
SEL-2725
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