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This is the eighth in a series of units that will educate you on the part played by a battery in an uninterruptible power supply (UPS) system. IEEE Standard 1187 establishes the recommended practices for the design and installation of valve-regulated lead-acid (VRLA) batteries.  The purpose of this paper is to highlight the most significant considerations identified in that standard, including: Safety considerations Design consideration Receiving and installation procedures IEEE 1188, which was discussed in Unit 8, describes the procedures for acceptance (commissioning) tests, including Pretest requirements Test procedures Corrective actions In general, work on batteries should only be performed by knowledgeable personnel who have proper training/certification, proper tools, and personal protective equipment (PPE).  IEEE Standard 1657 establishes minimum curriculum for battery technician certification.  Prior to any task involving contact with a battery, a job hazard analysis should be conducted to identify any potential hazards that might be encountered. Safety considerations HAZARD NOTIFICATION -  Proactive notification of an impending failure is far better than reactive alarms after a failure has occurred.  Continuous (real-time) monitoring is an indispensable tool that, when properly used, can detect and predict failures before they turn into fires, melt-down, arc flash, or other catastrophic failures.  Battery monitoring should always be installed by certified technicians, preferably prior to commissioning. SHOCK HAZARD -  Because most UPS system batteries are rated for greater than 50 Vdc, electrically-rated and/or insulated gloves should be worn.  Energized parts, such as terminal posts and intercell connections, should be insulated or shielded; shields should be removable when a section of the battery is being serviced. GROUND FAULT DETECTION -  GFD is recommended (or may be required by code) for most battery systems, depending upon the grounding method used.  Refer to local codes or IEEE 1187 for guidelines.  The UPS design will usually dictate the [...]

This is the seventh in a series of units that will educate you on the part played by a battery in an uninterruptible power supply (UPS) system. Early on in a UPS design a decision must be made on whether batteries should be installed on racks or in cabinets.  Both have pros and cons.  The following are typical design considerations. Battery technology Vented lead-acid (VLA) (frequently referred to as “flooded” or “wet cell”) batteries, which are sometimes used on very large UPS systems, are ALWAYS rack-mounted. Valve-regulated lead-acid (VRLA) batteries can be mounted on racks or in cabinets.  The remainder of this paper will address considerations for VRLA placement. Size Generally speaking, the larger the battery (both physically and ampere-hour rated), the more likely a rack configuration will be considered.  There are no hard and fast rules, but typically once a battery unit (single-cell or multi-cell) gets above 100 AH, it favors rack-mount.  Below that, cabinet mounting should be considered. Number “Number” refers both to the number of cells in a string, and the number of strings.  UPS systems frequently operate at high dc voltages (e.g., 250 to 800 Volts).  An analysis must be made on whether to have a minimum number of battery strings using physically large units, or to have multiple strings of physically smaller units.  Such decision is outside the scope of this paper, but it would include analysis of reliability (e.g., where and how many could the single-point failures be?) and maintainability (e.g., when is a unit too large for a person to handle, thereby requiring special handling equipment?).   Every cell-to-cell connection is a potential single point of failure.  Redundancy can increase or decrease reliability, depending upon the number of failure points.  Anything over about 23 kilograms (50 pounds) is probably too heavy to lift safely.  [...]