January-February 2009

UPS Systems Reliable Power Delivery

The worlds increasing reliance on technology translates to an equal demand on energy. That escalating dependence has taken power interruptions from annoying to critical mass.

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By Lori Lovely

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Building a Better Mousetrap Means a More Efficient, Reliable System
“Four years ago, we launched the first UPS platform,” reminisces Davis. “It was cutting edge technology.”

Since then, Eaton has continued to take the lead, and now, as product manager Pedro Robredo puts it, Eaton has “made a natural progression from a lower to a higher power range.”

Eaton recently introduced a new and extended power rating for its industry-leading Powerware 9395 UPS, with 825 kVA. Davis says customers wanted more powerful systems to support their critical business processes. The 9395 not only provides more power with 94% efficiency, but it also offers cost-saving scalability across a wide load range. Furthermore, it’s designed to be field upgradable by adding modules to achieve N+1 redundancy or to provide additional capacity.

Because a single large UPS unit can also be a single point of failure causing continued disruption of other systems, many businesses prefer multiple smaller integrated modules for equal but redundant power protection. A N+1 system is designed to supply more power than is required, so that one module can be down for service in the case of a failure without interruption, explains Robredo.

“You used to have separate modules for bypass, reducing the chance of failure of multiple items,” elaborates Davis. “With our modular system, you have redundant power modules set up to be removed if catastrophe strikes. You don’t have to remove the whole box. That speeds up repair and recovery time [when you have to reset all the servers], which is even more critical than downtime. When the power goes out, this gives you time to secure the system and the data; you have time to fix the problem. There’s no such thing as load sharing or load dumping; even onsite generation can fail.”

Another advantage of the N+1 system is that it readily accommodates expansion to increase capacity by combining additional units. Although it wasn’t always possible to combine the output voltage of two separate UPS units because the output waveform of one invariably led or lagged behind the other, causing damaging power fluctuations, Eaton’s patented Hot Sync technology alleviates that potential problem.

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Hot Sync technology allows UPSs with different power ratings to be paralleled together to provide “clean, continuous power,” states Davis. Eaton’s patented wireless paralleling technology eliminates the need for centralized controllers and complicated control wiring. A special synchronization signal is shared by the modules to insure they’re in synchrony, without leading or lagging waveforms.

Multiple redundancy provides an additional layer of protection. Rather than connect individual power supplies into a single UPS, each is connected to its own UPS, ensuring continued operation in the event of the failure of an individual unit. Because there’s no master/slave arrangement in Eaton’s system, Davis says the scalable architecture is easily expandable for greater flexibility. Next Page >

What Do You Think?

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swizznowt

February 26th, 2009 1:23 PM PT

I do not understand how four - 35" wide 225 kVA units plus a CLC cabinet will have a smaller footprint than one - 130" wide 750 kVA unit without a CLC cabinet. Please explain.

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