Hitachi Relion 670 Series Applications Manual page 402

Section 20
Security
20.3.1 Application
Change lock function CHNGLCK is used to block further changes to the IED configuration once the
commissioning is complete. The purpose is to make it impossible to perform inadvertent IED
configuration and setting changes.
However, when activated, CHNGLCK will still allow the following actions that does not involve
reconfiguring of the IED:
• Monitoring
• Reading events
• Resetting events
• Reading disturbance data
• Clear disturbances
• Reset LEDs
• Reset counters and other runtime component states
• Control operations
• Set system time
• Enter and exit from test mode
• Change of active setting group
The binary input controlling the function is defined in ACT or SMT. The CHNGLCK function is
configured using ACT.
LOCK
Change lock functionality can be temporarily disabled/overridden using Maintenance menu.
Maintenance menu/Recovery Menu (Password Protected)/Turn off Change-lock (Temporary).
Turning off the change-lock will override the change lock function until the next reboot of the IED. In
this case, the change lock function cannot be activated, and the Override output will indicate that the
change-lock is overridden.
20.4 Denial of service SCHLCCH/RCHLCCH
20.4.1 Application
The denial of service functionality is designed to limit the CPU load that can be produced by Ethernet
network traffic on the IED. The communication facilities must not be allowed to compromise the
primary functionality of the device. All inbound network traffic will be quota controlled so that too
heavy network loads can be controlled. Heavy network load might for instance be the result of
malfunctioning equipment connected to the network.
396
Binary input signal that will activate/deactivate the function, defined in ACT or SMT.
When CHNGLCK has a logical one on its input, then all attempts to modify the IED
configuration and setting will be denied and the message "Error: Changes blocked" will
be displayed on the local HMI; in PCM600 the message will be "Operation denied by
active ChangeLock". The CHNGLCK function should be configured so that it is controlled
by a signal from a binary input card. This guarantees that by setting that signal to a
logical zero, CHNGLCK is deactivated. If any logic is included in the signal path to the
CHNGLCK input, that logic must be designed so that it cannot permanently issue a
logical one to the CHNGLCK input. If such a situation would occur in spite of these
precautions, then please contact the local Hitachi Energy representative for remedial
action.
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