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Save power with efficient UPS

IT Managers need to control energy consumption, emissions and costs as well as maximise computing power from limited floor space. Advanced UPS technologies can help meet these demanding requirements as well as protect critical datacentre loads.

Datacentre managers have a difficult task specifying UPS systems which will cater for future needs with IT power consumption up 400% per server rack since 2003 and no sign of any slow-down. Added to this is the pressure to reduce carbon and physical footprints plus rising electricity costs and economic constraints.

The exponential growth in internet applications, processing power and data storage is definitely outstripping the level of protection for which existing UPSs were originally designed. This means that many legacy systems are incorrectly sized for today's needs and insufficient for continued load expansion. In addition, inefficient systems use excess electricity and create needless heat emissions. There is also a real risk of failure just when power continuity for mission critical loads is more important than ever.

Modular UPS Solutions
The need for datacentre efficiency, flexibility and availability has been fundamental in the development and uptake of modular UPS solutions. The scalability of modular architecture can deliver major reductions in electricity consumption and carbon emissions as well as enable flexibility in plans for power and space to allow for immediate and changing future requirements.

If a datacentre manager tries to allow for future power requirements with a traditional stand-alone UPS system it can lead to over-specification. This can then create a wasteful gap between installed capacity and the size of the actual critical load as well as making inefficient use of costly floor space.

However, rack-mounted configurations can be right-sized by inserting or removing 'hot-swappable' modules, enabling power to be added as requirements grow without any footprint penalty.  This hot-swap technology along with significant reductions in repair time can also achieve 99.9999% availability.

Modular, transformerless UPSs with Decentralised Parallel Architecture (DPA) provide a flexible, space-efficient and transferable system to static standalone installations that run the risk that they may never be used to capacity and would be difficult to relocate.

Datacentre managers have to seek space savings for their IT systems and equipment as a result of energy and environmental considerations coupled with the high costs of property particularly in city centre locations. Any space saving is a bonus when demand for power can often lead to plant being larger than the datacentre it is there to support.

A number of space-consuming IT deployments combined with property design and layout restrictions can create physical constraints on subsequent server installations and supporting infrastructure especially in old or converted locations.

Modular rack-mounted transformerless UPS systems offer flexible and space-saving solutions while meeting exacting performance specifications since they provide high power density and the smallest physical footprint available. In comparison to legacy systems, such modular UPSs typically take up only 25% of the floor space.

Cost of Failure
While major investments have been made in expanding and upgrading IT systems, many are still reliant on single stand-alone UPSs with Centralised Parallel Architecture (CPA). While this sharing of common components may offer some cost benefit, the centralised configuration introduces a number of 'single points of failure' into the system, which adversely affect its availability.

Decentralised systems are uniquely designed to remove single points of failure, achieving virtually zero downtime and the elimination of costly disruptions to mission critical operations.  The additional capital expenditure on a DPA system will be recouped through availability gains and by providing enhanced protection against revenue losses caused by system failures.

Decentralised Parallel Architecture works by paralleling independent rack-format UPS modules. This means that each individual module contains all the necessary hardware and software required for full system operation. With all critical components duplicated and distributed between the independent modules, potential single points of failure are eradicated, giving guaranteed system uptime.

With a minimum of one module over and above that required by the ‘capacity’ system, the load is supported with UPS power if any one module shuts down, thereby providing full N 1 redundancy and significantly increasing system availability.

Cost Savings & Improved Efficiency
Modularity improves efficiency by working closer to the load capacity than traditional UPSs without sacrificing the security of the system. The more a load approaches the capacity of any UPS, the more efficiently the UPS operates. A traditional stand-alone parallel redundant system is typically just 50% loaded while a modular solution typically achieves a 70% or higher loading which reduces both energy and UPS cooling requirements.

The initial purchase premium of an advanced modular system is more than compensated by the savings in annual running costs, emissions and floor space achieved. The scalability of modular systems also contributes major savings by providing redundancy if one of the units fails and spare ways that can accommodate an increase in capacity in affordable, incremental steps without interruption to the critical load. The stand-alone system provides no redundancy and the addition of a second parallel unit to increase capacity would result in additional costs and more space required as well as incurring downtime during installation. When compared with conventional parallel protection systems, decentralised modules reduce electricity costs, heat loss and CO2 emissions while delivering the industry’s smallest footprint and N1 parallel redundancy.

Blade Servers
Datacentres are dynamic computer environments and increasingly the mix of old and new computer technologies is causing the overall power factor of servers to shift towards unity. With the introduction of powerful blade servers the overall power factor may even become leading which creates a problem for legacy UPS installations. These mostly use pulse width modulated (PWM) technology which provides maximum power into lagging power factors.  As the load type changes from lagging to leading, these UPSs rapidly approach their kW power limits or can even go into overload. Replacing the existing legacy UPS with a higher output unit is expensive and usually causes disruption with changes in the power distribution and installation. Adding a second such UPS incurs even higher cost plus creating extra demand on premium floor space.

Instead, the best approach uses a modern transformerless UPS with adaptive inverter switching which derates far less severely than a legacy double conversion system as the power factor moves to leading. This improved efficiency means that a lower power system can be specified. Improved operating efficiency of UPS systems reduces the burden on air-conditioning in computer centres which further contributes to energy efficiency. Transformerless design also imposes a reduced total harmonic current distortion on its input (THDi). By eliminating the transformer UPS can be considerably smaller and lighter as well.

The electricity consumption of datacentres can be managed and reduced by alleviating the burden on cooling systems through matching the capacity of UPS systems to their respective critical loads. State-of-the-art modular, transformerless UPS systems are much more flexible than their traditional counterparts at matching load requirements and delivering optimum efficiency which enables datacentre managers to cost-effectively meet their power performance, space planning and environmental objectives.


  • Pelco
  • Schneider Electric Partner
  • APC Partner