Georator T3UPS-33-700K, Instruction Manual

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Both UPSs are running in normal mode under normal conditions. When one of them
has a problem, the load will still have protection from the inverter and battery. If
UPS1 fails and UPS2 is running normally, the load is unaffected, and supplied from
UPS2. If UPS2 fails and UPS1 is running normally, UPS2 will transfer the load to
UPS1 and the load will continue to be protected by the inverter and battery of UPS1.
If both of them are running normally, UPS2 takes up all load and UPS1 bears no
load. Therefore, UPS1 has a longer MTBF than UPS2 (can be interchanged after a
period of time), and their MTBF multiplies to a very large MTBF.
This type of redundancy is employed most frequently. When mains fail, UPS2 is the
first to contribute its battery to back-up the load. When UPS2’s batteries are
exhausted, the load is transferred to UPS1. Therefore, this topology can make full
use of the batteries of both units. User get a system that has redundant protection
and double the back-up time.
Another less expensive solution (see the figure below) is available if the load is
separated. A user may intend to install two UPSs, each with the same power, and
supplying half the load. A third UPS can be installed as backup to two main UPSs.
It is statistically improbable that both main UPSs concurrently break down.
Therefore, the third UPS can serve as a hot standby to two UPSs.
These topologies make full use of the resources to create the best protection and
longest MTBF.
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