Mass Transit

FEB 2015

Mass Transit magazine features agency profiles, industry trends, management tips and new product information.

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26 | Mass Transit | MassTransitmag.com | FEBRUARY 2015 TECHNOLOGY & SOFTWARE • Logic cards, switching and control cards, power cards and related devices that fa- cilitate PBX operation • Stations or telephone sets, sometimes called lines • Outside telecommunication trunks that deliver signals to and from the PBX • Console or switchboard to control in- coming calls • Backup power system consisting of sen- sors, power switches and batteries • Interconnecting wiring • Cabinets, closets, vaults and other housings The Backup Power System Te primary use of the battery backup system is to keep the PBX system oper- ating during a power failure. Other ways that the battery backup system can ofer protection is during: • Lightning strikes • Power surges from motors and equip- ment being switched on and of • Power spikes and sags • Electrical noise or high frequency dis- ruption from nearby equipment • Frequency instability • Harmonic distortion, which may afect audio quality Periodic maintenance of the system is required for optimum performance. Tis in- cludes replacement of the backup batteries. PBX System Upgrade: A Step-by-Step Guide Recently, a transit system sought to retain a contractor to remove, dispose and install batteries at eight PBX locations within its service area and to install battery discon- nect switches at four PBX node locations. Many of the previous batteries had failed prematurely, lasting only 12 to 16 years — just three-quarters of their life expectancy — due to the hot operating environment. Te issue was addressed and changes were made to the environmental systems at these locations. Afer careful analysis, the battery procurement and installation was out- sourced. Te bid invitations specifed valve-regulated lead-acid (VRLA) batter- ies, plus labor, material and equipment necessary to remove, dispose and install the new backup system. Te battery manufacturer and its ex- clusive distributor performed all services, working together as a single vendor. Tis provided a single point of contact for the customer to make for easier project man- agement. As a reference for other compa- nies who are installing or replacing their PBX batteries, here is an outline of the steps involved in the process. INITIAL WALKTHROUGH EnerSys and its distributor National Rail- way Supply performed a comprehensive site survey, evaluating the battery envi- ronment for anything that might impact battery performance and longevity, such as temperature, moisture and contam- inants. Tey also assessed the space re- quirements and rack placement to ensure that the batteries could be easily accessed for future service and to ensure that there were no safety concerns. BATTERY SELECTION AND SIZING Te team recommended a battery solution designed specifcally for communication applications. Te selected VRLA batter- ies featured thick positive plates for long life and recombinant technology. Other features included a welded/epoxy, dual post seal design for high integrity seal, large copper post design for high rate performance and protective steel cans to maintain constant, uniform compression for the life of the cell. Te team also re-evaluated the size of the batteries needed. Tis is important as both application demands and the size of the manufacturer's prod- uct can change during the life span of the batteries. In terms of the application, the number of phone lines and devices may have increased, as well as the amount of electrical noise and system disruptions, re- quiring more battery power. Regulations also may have changed over time, requiring backup systems to provide longer standby coverage duration during crisis situations. INSTALL REDUNDANT BATTERIES Calculating accurate run times is im- portant for determining the amount of battery coverage that is required in the interim stages when temporary batteries are installed to back up the system prior to installation. Using these assessments, the required runtimes were determined and they switched the system from the old batteries to temporary units. INSTALL BATTERY DISCONNECT SWITCHES: Te team installed battery disconnect switches for workability, allowing them to switch between the main and secondary batteries in case of a battery failure and for future routine maintenance.

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