M.2
SEL-751 Relay Instruction Manual Date Code 20170927
Cybersecurity Features
Configuration Management
The SEL-751 supports strong passwords with as many as 12 characters, using
any printable character, allowing users to select complex passwords if they so
choose. SEL recommends that passwords have a minimum of 8 characters and
include at least one of each of the following: lowercase letter, uppercase letter,
number, and special character.
Ethernet protocols Telnet and FTP require the proper passwords to gain access
to level-protected functions. Ethernet protocol MMS requires a password to
gain access if MMS Authentication is enabled via the CID file. See Section 7:
Communications for more information on access restrictions for the Ethernet
protocols.
Monitoring and
Logging
The SEL-751 provides Relay Word bits that are useful for monitoring relay
access:
➤ SALARM—Pulses for approximately one second whenever a
user gains access to Level 1 or higher, when an incorrect
password is entered when attempting to access Level 1 or
higher, or when a setting is changed.
➤ PASEL, PBSEL—Asserted while the Ethernet port(s) is active.
➤ LINK1, LINKA, LINKB—Asserted while the link is active on
the Ethernet port(s). Loss of a link can be an indication that an
Ethernet cable has been disconnected.
➤ LINKFAIL—Asserted if link is lost on the active IP port (ports
1A or 1B).
These bits can be mapped for SCADA monitoring via DNP3, IEC 61850,
Modbus, or SEL Fast Message. They also may be added to the SER for later
analysis or assigned to output contacts for alarm purposes.
The SEL-751 SER is a useful tool for capturing a variety of relay events. In
addition to capturing state changes of user selected Relay Word bits, it
captures all power-ups, settings changes, and group switches. See Sequential
Events Recorder (SER) Report on page 10.37 for more information about
SER.
Physical Access
Security
Physical security of cybersecurity assets is a common concern. SEL-751
relays can be installed within a control house that provides physical security.
Other times, relays are installed in breakers or enclosures within the
switchyard. The SEL-751 provides tools to help manage physical security,
especially when the unit is installed in the switch yard.
You can monitor physical ingress by wiring a door sensor to one of the
SEL-751 contact inputs. This input can then be mapped for SCADA
monitoring or added to the SER log so that you can monitor when physical
access to the relay occurs.
It is also possible to wire an electronic latch to an SEL-751 contact output.
You could then map this output for SCADA control.
Configuration Management
Many users are concerned about managing the configuration of their relays.
The SEL-751 provides mechanisms to help users manage relay configuration.
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