DCA REVIEW Industry Trends & Standards
What do today’s data centres expect of their UPS?
UPSs that effectively protect their critical load from mains power failures and disturbances are essential to modern data centres. To successfully fulfil this role in today’s business conditions, they must do so while offering near-perfect availability, high efficiency and easy scalability. In this article, Kenny Green, Technical Support Manager at Uninterruptible Power Supplies Ltd (UPS Ltd), a Kohler company, looks at how available UPS topology allows data centre operators to meet these exacting requirements.
TODAY, no data centre operates without an uninterruptible power supply (UPS) in place to protect the load from mains-related disturbances and power failures. If the load is unprotected, such events have the potential to cause irrevocable damage to IT hardware. Significant as this damage could be, it is unlikely to be as serious as the impact on business and reputation resulting from loss of data, or IT availability in a 24/7 online service environment.
With this in mind, data centre operators will judge a UPS by its level of availability, combined with the quality of protection it provides from mains failures and transients while on-line. However, current business, economic and even political conditions impose other pressures. The greatest of these is the need to improve energy efficiency. Although this is largely to minimise the steadily increasing cost of energy, cutting
20
www.dcsuk.info I May 2014
carbon emissions and ‘Going Green’ is also increasingly important. Another factor imposed by modern conditions is that data centres’ processing loads can change rapidly as demand for IT resource grows. To remain effective, UPSs must be readily scalable to keep pace with these rapid changes.
Meeting the requirements of today’s data centre users Today’s UPSs allow data centre operators to overcome these issues. To see how they do so, we can look more closely at their technology, and at how they utilise this technology to fulfil their role.
Fig. 1 shows the major UPS components. Incoming raw mains is fed to a rectifier/ charger for conversion to a DC output. This output supplies the inverter input and charges the UPS battery. When the incoming mains supply is available, the rectifier/charger keeps the battery fully charged, while the inverter also uses its DC level to develop an
AC output for the critical load. If the AC mains supply fails, the inverter draws DC from the battery.
Because the battery is part of the DC bus, switchover between battery and rectifier, and back again, is seamless. The mains failure is entirely invisible to the critical load, provided it lasts less than the battery’s autonomy. The critical load is protected from incoming power aberrations as well as failures. The UPS rectifier and inverter provide a barrier to mains-borne noise and transient voltage excursions in addition to providing a well- regulated AC output.
Given that the UPS’s mains failure protection capability is subject to its battery autonomy, operators must have a strategy for handling power outages that exceed this. This strategy depends on whether or not the load must continue running throughout the mains failure. If this is not essential, a battery
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56