Transformerless UPS : “the most economical choice”

In our mission to provide you with relevant information on UPS and related data center technologies from experts around the web, we want to draw your interest to an article from our business partner UPSL once more. In this article Kenny Green, Technical Support Manager for Uninterruptible Power Supplies, a Kohler company explains why transformerless UPS systems are ultimately the most economical choice. He deeply investigates the benefits of the lower Total Cost Of Ownership (TCO) and reveals that that transformerless topology offers savings benefits due to improved operating efficiency and other factors.

One striking example he shares with us:

“In this example, a 100 kVA load is supplied by two 120 kVA modules in a parallel N+1 redundant configuration. We can compare the results from a transformerless implementation with those from using transformer-based modules. In either case, each module runs at 42% load; at this level, the transformerless solution will operate at 96% efficiency while the transformer-based pair will return just 91%. If their 100 kVA load has a power factor of 0.8, it will draw 80 kW from the UPS. The transformer-based solution will draw 88 kW from the utility mains to service this, while the transformerless UPS will take 83 kW.

Simple arithmetic shows how this 5 kW efficiency improvement accumulates into a worthwhile reduction over a year: 5 kW x 24 x 365 = 43800 kWh savings. Assuming an electricity cost price of 9.0p/kWh, this equates to a direct energy cost saving of £3942 each year. Further savings arise as the improved efficiency reduces heat losses and therefore air conditioning requirements. In this example, this could typically save a further £1000 or more over a year. Accordingly, total savings over five years from going transformerless could amount to as much as £25,000.

Going transformerless also saves costs by improving the power factor imposed on the utility mains from 0.8 to 0.98. This reduces the reactive current drawn by the UPS, therefore the sizing required for its upstream switchgear and cabling, as well as external power utility metering and possibly penalty charges.”

To find out more about further cost-saving factors of transformerless UPS please follow this link.

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