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ABB Substation Automation
Products and Systems
4.1.1.7
4.1.1.8
1MRS750940-MUM
Technical Reference Manual
MMI module
The MMI of the relay is equipped with six push-buttons and an alphanumeric LCD
for 2 x 16 characters. The push-buttons are used for navigating in the menu structure
and for adjusting set values.
An MMI password protects all user-changeable values from being changed by an
unauthorised person. The default value for the MMI password is "999". With the
default value the password is not active and it is not required for altering parameter
values. For further information, refer to "Operator's Manual".
Self-supervision
The self-supervision system of the relay handles run-time fault situations and informs
the user about an existing fault. When the self-supervision system detects a permanent
internal relay fault, the ready indication LED starts blinking. At the same time the
self-supervision alarm relay that is normally picked up drops off and a fault code
appears on the display. This code is a number that identifies the fault type. For fault
codes, refer to section "Internal fault" in "Operator's Manual".
READY
START
TRIP
INTERNAL FAULT
FAULT CODE : 56
C
E
Figure 4.1.1.8-1 Internal fault
Fault codes can indicate:
• No response on output contact test.
• Faulty program memory, work memory or parameter memory.
• Internal reference voltage error.
REJ 523
11
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