| On the one hand, there's the management issue | | | | Distributed UPS means that the business is |
| of controlling several smaller units attached to vital | | | | grouped into data processing clusters, each with |
| equipment or each separate network. On the | | | | dedicated UPS protection, giving several smaller |
| other, the cost and reliability implications of having | | | | power plants spread across the whole operation. |
| to install a dedicated ring main system for power | | | | Distributed UPS often require lower capital outlay |
| management; if the central UPS fails, so does the | | | | and installation costs. Some suppliers claim higher |
| whole system! | | | | overall operating efficiencies because the number |
| When planning business continuity, a centralised | | | | of conversions from mains AC to DC is reduced - |
| UPS is normally more powerful, functional, | | | | leading to energy savings. |
| sophisticated and automated than a solution based | | | | The primary advantage of centralized UPS |
| on a distributed architecture. What's more, it's | | | | Smaller UPS generate less heat than larger ones, |
| usually housed away from the main data centre. | | | | leading to greater efficiency. Distributed systems |
| Distributed UPS, however, is simpler and less | | | | also reduce the total number of power conversion |
| costly to install; vital equipment can be protected | | | | steps; consequently, electronic components and |
| independently, and thus it is shielded from a | | | | circuit complexity are both reduced. Distributed |
| central power outage. | | | | solutions, however, generally have more |
| Deciding on a UPS solution? | | | | components, which could increase the likelihood of |
| When planning power and business continuity, one | | | | breakdown. As each data centre processing |
| of the main issues is to protect against | | | | cluster has its own uninterruptible power supply, |
| 'single-points-of-failure'. In practice, both centralized | | | | confusion about which equipment is protected |
| and distributed UPS solutions work well - providing | | | | against power outage by which UPS is eliminated. |
| the system is designed with appropriate | | | | Likewise, maintenance and battery changes are |
| redundancy and a built-in maintenance by-pass | | | | localised to individual clusters thus reducing |
| (allowing UPS maintenance without loss of power | | | | downtime elsewhere in the business. |
| to the load). | | | | The primary advantage of centralised UPS over |
| A centralised uninterruptible power supply usually | | | | smaller, distributed UPS lies within batteries. |
| forms part of the facility, as it has to be housed | | | | Smaller UPS contain sealed lead-acid batteries - |
| securely away from the main business. In the | | | | with a typical design life of five years or less. The |
| past, these systems were only meant to protect | | | | cost implications of this depend on the number of |
| against short-term power outage but this is now | | | | UPS clusters. Larger batteries, used in centralised |
| changing. With modern UPS regarded as a lifeline | | | | UPS, have longer design lives. |
| service, battery back-up, failover, redundancy and | | | | Another business continuity benefit of centralised |
| maintenance by-pass are all now an integral part | | | | UPS is that, being housed away from 'busy' areas |
| of their design. Centralised solutions use a single | | | | of the building, it is less easily disrupted, |
| UPS to feed a custom built ring main, which | | | | accidentally damaged or maliciously interfered with. |
| supports numerous items of critical load or | | | | Always invest in expert UPS consultancy |
| dedicated networks. | | | | In conclusion, distributed UPS, though easier and |
| The alternative is a distributed/decentralised | | | | less costly to expand, can cost more per-kilowatt |
| system, with each piece of data centre | | | | than a centralised system. Centralised systems, |
| equipment powered by a smaller individual UPS. | | | | however, are more expensive initially to build and |
| Load utilisation and your uninterruptible power | | | | must be carefully designed to meet future |
| supply | | | | business continuity needs. Large-scale |
| In terms of load utilisation and battery capacity, a | | | | Power-over-Ethernet (PoE) deployments of IP |
| centralised uninterruptible power supply can be | | | | phones, wireless access points, internet security |
| more versatile and cost efficient. However, the | | | | cameras and other peripherals may favour a |
| installation of a dedicated ring main can be | | | | centralised uninterruptible power supply solution |
| expensive - especially if the loads are spread | | | | through lower whole-life costs. |
| around a building. While distributed solutions may | | | | When planning power and business continuity, the |
| not optimise load capacity and extended run time, | | | | wisest option is to treat each network on a |
| the effects of UPS failure may be reduced when | | | | case-by-case basis and always invest in expert |
| compared to the business continuity implications | | | | UPS and business continuity consultancy. |
| of a poorly-designed, failed centralised UPS. | | | | |