Published on Wednesday, Mar 10 2010 by
Advances in UPS technology and system flexibility mean there are now many more opportunities to optimise installations for increased efficiency and availability, or to reduce costs and emissions. Rising energy demands and pricing, along with pressure to shrink carbon footprints, make these achievements all the more attractive to contractors, consultants and customers alike.
Choosing the correct UPS system to support a connected critical load is not simply a matter of matching the output power to a given load. The solution must also take into account reliability, availability and expandability among other factors.
Modern UPS technologies, such as transformerless, modular configurations, are providing new ways to save energy and costs including rightsizing the UPS over time; higher efficiency for partial loads; lower cooling requirements; improved input power factor; and improved input current total harmonic distortion.
Tandem back-up
With growing dependence on power for critical processing and communication applications, often nothing less than 24/7 availability can be tolerated.
However, while the recognised solution for continuous power is the combination of a UPS and standby generator, they do not naturally have plug ‘n’ play compatibility. Individually sourced units present a risk of mis-sizing, causing installation and commissioning problems and potentially compromising system autonomy. For example, the generator output voltage may be acceptable to the UPS, but often the generator’s frequency range is wider than the UPS is designed to accept.
Turnkey supply and installation of UPS and generator delivers valuable integration benefits, eliminating potential points of failure and ensuring a true ‘no-break’ solution in the event of an extended power failure.
Further, the problem of demarcation between different suppliers is eliminated and the complexities of matching UPS and generator are resolved, alleviating concerns for the consultant, contractor and end user. Significant cost savings and operating efficiency can also be gained.
Transformerless technology
Of the three main types of UPS system, off-line, line-interactive and on-line, implementations of on-line double-conversion UPS systems have proven most effective, especially with critical loads such as computer rooms and data centres, because they offer the most comprehensive protection against mains supply problems and consequently deliver the highest levels of system availability.
Transformerless three-phase UPS are now widely adopted, delivering significant weight and space savings and enabling the development of today’s modular systems.
Space saving
Modular, rack-mounted transformerless UPS are ideal for applications where space is at a premium or where access on site is difficult. Typically only a quarter of the footprint and weight compared with traditional free-standing UPS units, they provide important savings on floor space and installation costs.
Modular UPS provide high efficiency and power density, while vertically scalable modules mean that additional capacity for redundancy or load upgrades can be easily achieved at a fraction of the cost of an additional stand-alone unit.
Right-sizing
There is huge potential to reduce electricity consumption, and to alleviate the burden on stretched cooling systems, by continually matching the capacity of UPS systems to their respective critical loads.
Trying to cater for future needs with stand-alone UPS systems can lead to over-specification, creating a wasteful gap between installed capacity and the size of the actual critical load. Such inefficiencies mean that companies could be burning excess electricity and creating needless heat emissions, compromising efforts to control costs and reduce their carbon footprint.
The flexibility and scalability of modular rack-mounted systems means they can be ‘right-sized’ from the outset by inserting or removing ‘hot-swappable’ modules, enabling power to be cost-effectively added as requirements grow, without any footprint penalty and with zero downtime.
Decentralised UPS
Parallel UPS systems comprise either centralised parallel architecture (CPA) or decentralised parallel architecture (DPA). While CPA systems offer a cost benefit by sharing common components, the drawback is that this centralised configuration introduces a number of ‘single points of failure’ into the system, which adversely affect its availability.
As well as valuable efficiency benefits and low total cost of ownership, decentralised UPS configurations offer maximum system availability. Paralleled and independent UPS modules, containing all the hardware and software required for full system operation, eliminate potential single points of failure by cost effectively duplicating critical components within each module. With a minimum of one module over and above that required by the ‘capacity’ system, the load is supported with inverter power if any one module shuts down, thereby increasing system reliability and guaranteeing system uptime.
DPA technology undoubtedly comes at a premium, but the lower purchase price of traditional UPSs must be offset by significantly greater operating expenses. Considering ‘Total Cost of Ownership’, reductions in energy loss costs with modular DPA systems mean the higher initial outlay can be recouped within the first year of operation, with further savings achievable in the longer term.
Price and service
Budget is naturally a key criterion in the selection process for UPS and standby generators. However, it’s important to ensure that suppliers are not cutting costs and corners that will compromise power protection in the future or involve expensive upgrades. Cost-benefit analysis should consider the best price against supplier expertise, product technology and quality, scalability, and after-sales services.
Many suppliers will claim to offer good pre and post sales support, but in reality contractors and customers experience a great deal of variance in service levels. Rather than a ‘sell-and-leave’ approach, specialist UPS suppliers will offer bespoke solutions and add value through additional services, providing comprehensive support throughout the installation process, advising on related site works, and resolving any issues that arise.
This article has been published in Network Communications News (NCN) please click here to view the article.