Conformity Magazine - October 2007 - (Page 20)

Conventional batteries include: 1. Lead-acid based batteries A. Flooded Rectangular/Round Cells — Carriers, for over 30 years have been satisfied with the reliability of flooded lead acid round 2 V cells, which operate in the climate controlled environment of the Central Office. To match the DC plant voltage of -52.08 V, 24 cells are series connected to form batteries which are placed in parallel with rectifiers for continuous network operation even when commercial AC fails. Batteries are typically sized to provide 210 amperes for 8 hours or 1680 Ahs (ampere hours)s. Cells weigh close to 350 pounds and have an expected life of 15 to 30 years. The emergence of digitial loop carrier technologies, allowed carriers to provide network functionality beyond the confines of the Central Office. With the push for network decentralization in the 80’s, carriers seeked to provide network functionality in the uncontrolled and harsh environmental conditions of remote sites and the outside plants. For this transformation, carriers desired back-up batteries with round cell life, and reduced water loss, maintanance costs, and electrolyte spillage hazard. B. Valve-Regulated — The decentralization of the network and the deployment of the Outside Plant (OSP) provided a new market for battery technologies which could operate reliably in partially controlled and uncontrolled enviroments and work with minimal maintanance.In these environments, batteries would have to operate in cold (-40 °C) and warm (50 °C) temperatures. The first battery technology to be introduced into this new application was the Valve Regulated Lead-Acid (VRLA) battery. VRLA batteries typically use fiber separators for absorbed electrolyte and operate at voltages between 2.25 -2.27 at 25 °C. Unlike, round cells, VRLAs electrolyte is starved (The electrolyte is absorbed into the separator material and pores of the plates). To minimize water loss and maintanance, VRLAs use valves to recombine oxygen and hydrogen and maintain operational water levels. First designs of valve regulated lead-acid (VRLA) batteries were not accomodating. Major concerns with the first designs were with thermal instability, fire resistance, and unrealized service life. In response, Telcordia (Bellcore at the time) helped to gain consensus on the design, performance and safety of VRLA batteries. This industry colloboration led to the publication of Telcordia Special Report, SR-4228, “VRLA Battery String Certification Levels Based on Requirements for Safety and Performance”, December 1996 and the widespread deployment of the technology. (As of 2006, it is estimated that over 15 million VRLA batteries are in service.) VRLA batteries are now the major backup power source for the OSP environment. 2. Nickel based batteries A. Nickel-Cadmium - Nickel cadmium (NiCds) were introduced to compete against VRLA batteries in the OSP back-up power market. NiCds were designed to address carrier frustration with the shortcomings of VRLAs, - thermal instability, unscheduled maintenance, and unrealized service life. NiCds, which have a nominal voltage of 1.2 V, are flooded with an alkaline electrolyte of potassium hydroxide (KOH) and water . 38 to 40 NiCd cells are typically used to form a battery string that can operate on a typical telecom DC buss of 48 VDC. There has been widespread deployment of NICds, but the technology has not supplanted VRLAs in the OSP. Note: Similar to lithium batteries, another battery technology - Nickel-Metal Hydride (NiMH) – is geared for stationary power use. NiMH batteries were initially introduced in the electrical vehicle marketplace and in the consumer market. NiMH batteries are electrically similar to nickel cadmium batteries. NiMHs were developed to provide higher energy density than NiCds and are made with environmentally friendly materials. Similar to VRLAs, the NIMH electrolyte is starved and is also sealed to minimize maintenance and issues with leakage. 20 Conformity oCtober 2007 consider venting or leaking hazards as safe or permitted during normal operation. However, these hazards are permitted when the battery is intentionally forced to fail. The goal of the safety testing is to aid to carriers, emergency policy makers, first responders, and manufacturers to understand the hazards associated with battery service. All hazards are considered severe. In Part 2 Descriptions of the safety tests will be provided in Part 2 of this series of articles, which will appear in the November issue of Conformity. Jude Ken-Kwofie is a network engineer with Telcordia, and can be reached at jkenkwof@telcordia.com. To obtain copies of the GR-3150-CORE document, please e-mail document-info@telcordia.com. Notes 1. 2. Telcordia sold all rights of the PL-iON technology in 2000. A requirement, identified by the letter “R”, is a feature or function that, in the view of Telcordia, is necessary for client company product selection. Conditional requirements, identified by the letters “CR”, are features or functions that, in the view of Telcordia, are necessary in specific applications. Conditional requirements are considered requirements when considered necessary for client company product selection. In Telcordia’s view, objectives are desirable features or functions, which may be required by carriers. Objectives, flagged as “O”, represent goals to be achieved.. Conditionals objectives are features or functions that, in the view of Telcordia, are desirable in specific applications and may be required by carriers. In Telcordia’s estimation, conditionals, flagged as “Cn” are circumstances that will cause a conditional requirement or conditional objective to apply. 3. 4. 5. 6. 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Table of Contents Feed for the Digital Edition of Conformity Magazine - October 2007

Contents Editor’s Note Commission Proposes Changes for 57-64 GHz Spectrum Rules FCC Continues Actions Against Jamming Device Distributors Radio Operator Fined for Failing to Make Equipment Available for Inspection Commission Fines Unsolicited Fax Advertisers Firm Offering Quality Standards Training Also Fined Breaking New Ground with Lithium-Battery Generic Requirements for Use in Telecommunications Facilities ESD Open Forum EMC UK 2007 Conference Set Staying Abreast of U.S. E-Waste Legislation EU Commission Establishes RFID Expert Group Update on China's CCC Compliance Program System Level ESD Testing: The Waveforms An Alternative Approach to Surge Suppression Testing Equipment Buyer's Guide EU Scientific Committee Releases Updated Data on EMF Risks Updated Standards List For The EU’s EMC Directive Updated Standards List For The EU’s Directives on Measuring Instruments Call for Presentations for 2008 International ESD Workshop Announced CPSC Actions In The News IEC Standards Update Product Reviews UL Standards Update New Products From Our “You Can’t Make This Stuff Up” Department Looking Back: Items from Past Issues of Conformity Upcoming Events Advertisers

Conformity Magazine - October 2007

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