By referring to the Availability section we can see how PowerWAVE® modules can achieve very high availability - Six Nines, or 99.9999% - by reducing repair time to less than half an hour.
However for many mission critical systems in emergency service, medical, commercial or industrial applications, any downtime, however minimal is simply not acceptable. Although a static switch can transfer the critical load to the incoming mains without break during the UPS repair, this carries risk as load protection from mains disturbances has been removed.
UPS Configuration to Provide Redundancy
Most mission critical systems today rely on a parallel redundant power system configuration. All the UPS modules are connected in parallel via a common output busbar and continuously, and equally, share the load. If any single module fails the other module(s) have sufficient capacity to continue supporting and protecting the load without interruption. The redundant configuration of the modules has given the UPS system resilience to at least a single module failure. |
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Under normal operating conditions a PowerWAVE UPS system, consisting of three 50kVA power modules, provides protected power to a 100kVA load. Each UPS module is 66% loaded.
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In the unlikely event that one of the ups modules fails, it will isolate itself from the rest of the system while the remaining two modules continue to support the load with protected power. The faulty module may be hot-swapped out from the system and replaced while the UPS continues to provide protected power to the load with zero downtime. |
N + n Redundancy
More about how it works
A parallel redundant modular UPS typically has a configuration referred to as N + 1, where N is the number of modules needed to supply the load. The '1' signifies the presence of an extra module, giving the UPS sufficient capacity to fully support the critical load even if one module fails.
To increase supply security, the number of redundant modules can be increased to two, or in extreme cases, even more. The number of redundant modules - n within the N + n redundancy figure - is known as the coefficient of redundancy for the UPS system.
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