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5. REDUNDANCY ( SYSTEM BACK – UP )
Redundancy can be roughly divided in two types: serial (hot standby) redundancy and parallel (active)
redundancy.
A serially redundant system consists of two converters, with the output of the second converter connected
to the reserve input of the first converter.
Both converters are normally running.
protected by the first converter. If the first converter has battery support the load will still be supplied by the
first converter and its battery in the event of a power failure and the second converter is still in standby mode.
If the first converter should fail the load is automatically transferred from the output of the first converter to
its reserve input and then the second converter will supply the load thru the reserve input of the first converter.
The load is now being supplied entirely by the second converter and is now protected against overload etc. by
the second converter. If the second converter has battery support the load will still be supplied by the second
converter and its battery in the event of a power failure.
If both of converters are running normally, the first converter takes up the entire load and the second
supplies no load. In this case the second converter has a longer MTBF than that of the first.
can be interchanged after a period of time, and their MTBF multiply to a larger MTBF.
This is the type of redundancy employed most frequently. If the mains should fail, this topology can make
full use of the battery. This system provides double the protection and double the back-up time. It should be
noted that the total power output is not doubled.
The load is connected to the output of the first converter.
The load is being supplied entirely by the first converter and is
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However these
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