The telecommunications industry and other industries use backup power supplies or “uninterruptible power sources” (UPS's) to maintain operations when primary power sources fail or are interrupted. These UPS's are used to supply backup power to critical electrical and electronic equipment during primary power interruptions. Often these backup power sources include arrays of 2-volt valve-regulated lead acid battery cells (VRLA's). For example, a 48-volt backup power supply may include an array of twenty-four 2-volt VRLA's interconnected in series to supply backup power to critical equipment. Alternatively, a 24-volt backup power supply may include an array of twelve 2-volt VRLA's. These battery cells typically are supported on racks in a desired array. One such metal rack is described in U.S. Pat. No. 6,719,150. Such racks may support battery cells in a 3 by 8 array (48-volt array), or in a 3 by 4 array (24-volt array), for example, depending upon the desired or required amount of backup power.
The telecommunications industry has widely adopted a set of industry standards known as the NEBS (“Network Equipment—Building System”) standards. The NEBS standards were developed by Bell Labs in the 1970's to standardize equipment that would eventually be installed in either an Incumbent Local Exchange Carrier (ILEC) or Regional Bell Operating Company (RBOC) Central Office. The NEBS standards basically describe the environment of a typical or generic RBOC Central Office. Bell Labs' intent in developing the NEBS standards was to make it easier for vendors to design and supply equipment compatible with a generic RBOC Central Office environment.
The main NEBS standard is Bellcore (now Telcordia) GR-63-CORE “Network Equipment—Building System (NEBS) Requirements: Physical Protection” Section 4.4, entitled “Earthquake, Office Vibration, and Transportation Vibration,” provides generic criteria for earthquake, office vibration, and transportation vibration for telecommunications network equipment. Section 4.4.1 entitled “Earthquake Environment and Criteria” defines the seismic shaking conditions that must be withstood by a particular piece of equipment to be NEBS certified. This section requires the equipment to withstand a most severe “Zone 4 seismic event,” which is approximately equivalent to an earthquake having a rating of 8.2 on the Richter scale. GR-63-CORE section 5.4.1 defines the waveform testing requirements necessary to demonstrate NEBS GR-63-CORE seismic compliance. As yet, there is no known backup battery rack or support system that complies with the NEBS GR-63-CORE seismic testing requirements. In particular, there is no known modular rack or storage system that meets NEBS GR-63-CORE seismic testing requirements and is adaptable in size to either 24-volt or 48-volt battery arrays.
Accordingly, there is a need for a backup battery storage system that complies with the NEBS GR-63-CORE (Issue 2 Apr. 2002) seismic testing requirements. Preferably such a system is adaptable to either a 24- volt or 48- volt array of battery cells. In addition, such a system should be efficient to construct, should occupy a minimum amount of space, and should be relatively affordable compared to non-NEBS certified storage systems.