ABB REB 551-C3*2.5, Installation And Commissioning Manual, Page: 81 / 148

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Requirement of trig condition for disturbance
report Chapter 10
Requirement of trig condition for
disturbance report
1 Requirement of trig condition for disturbance
report
Disturbance reports, setting and internal events in REx 5xx are stored in a non volatile flash
memory. Flash memories are used in many embedded solutions for storing information due to
high reliability, high storage capacity, short storage time and small size.
In REx 5xx there is a potential failure problem, caused by too many write operations to the flash
memory.
Our experience shows that after storing more than fifty thousand disturbances, settings or inter-
nal events the flash memory exceeds its storing capacity and the component is finally defected.
When the failure occurs there is no risk of unwanted operation of the protection terminal due to
the self-supervision function that detects the failure. The terminal will give a signal for internal
fail and go into blocking mode.
The above limitation on the storage capacity of the flash memory gives the following recom-
mendation for the disturbance report trig condition:
• Cyclic trig condition more often then once/day not recommended.
• Minute pulse input is not used as a trig condition.
• Total number of stored disturbance reports shall not exceed fifty thousand.