“DC-grade” reliability for UPS in telecommunications data centers
Frank Bodi · 2007
Data Center reliability and the soaring cost of infrastructure are of major concern to businesses and Telcos. Traditionally data centers have been UPS-powered however on reliability grounds UPS are considered the "poor cousin" to their DC counterpart. This paper presents an analysis of UPS systems to show that a reliability matching DC systems is readily achievable. The paper will also discuss design options that are not required to achieve "DC-grade" reliability and which add substantially to the cost of a data center. The analysis was conducted to determine a set of configurations for use in a national standard by a leading Australian Telco. Configurations graded according to reliability enable a value comparison to be made between different UPS systems. A detailed reliability assessment was made of each configuration using Monte Carlo power system reliability modeling software. Traditionally DC tele power systems have been the cornerstone of reliable telecommunications power. As telecommunications advances rapidly towards an IP-centric network, the role and importance of Data Centers in telecommunications has surged. Data Centers however are traditionally AC powered and accordingly the importance of UPS systems to Telcos has increased dramatically. Emerging telecommunications platforms do not always have a DC powering option therefore highly-dependable UPS systems are needed. The problem is that UPS systems typically provide an order of magnitude lower reliability. High-end DC systems can readily attain an MTBF of 200+ years while UPS systems typically achieve as little as -10-30 years MTBF. With the cost of modern data centers soaring, the paper will show how such costs can be contained while designing UPS systems with "DC-grade" reliability.