Standby battery supplies

The electricity supply to the fire alarm installation must be secure in the most serious conditions. In practice the most reliable supply is the mains supply, backed up by a standby battery supply in case of mains failure. The supply should be exclusive to the fire alarm installation, fed from a separate switch fuse, painted red and labelled, Fire Alarm - Do Not Switch Off . Standby battery supplies should be capable of maintaining the system in full normal operation for at least 24 h and, at the end of that time, be capable of sounding the alarm for at least 30 min. 

Table 50.11 LCP range small-size flat-plate lead-acid standby batteries supplied by Chloride Power Storage...

The control and snpervision of a snppression system is achieved rising an electrical power/control unit with 24-horir (minimum) standby battery backup power. The unit supplies sufficient energy to accomplish the following (NFPA69 1997) ... 

Batteries have many advantages over other power sources, as outlined in Table 6.1 They are efficient, convenient, and reliable, need little maintenance, and can be easily configured to user requirements. As a result, batteries are used in an extremely wide range and variety of sizes and applications—from as small as 3 mAh for watches and memory backup to as large as 20,000 Ah for submarine and standby power supplies. 

Large battery installations which are called upon only occasionally to supply power, usually in emergency or auxiliary power supply circumstances, are referred to as stationary or standby batteries. Sueh installations having total capacities in hundreds of ampere hours are commonly in use. Figure 32.1 illustrates a large secondary lead-acid battery installation. 

To be able to advise on this the battery manufaeturer needs to know what is required in terms of eurrent output, voltage and frequeney of operation. If only one continuous load is to be supplied, sizing the battery can be simple. For example, an emergency lighting system drawing 20A for 3 h on battery power would require a 60Ah battery at the 3 h rate. Since standby batteries are conventionally rated at the 10 h rate, this is equivalent to a 75 Ah battery at the 10h rate. 

In either case a standby battery of proven reliability and maximum compactness is required, which is capable of supplying a high discharge current for a comparatively short period. 

Chloride Industrial Batteries also supply high-performance flat-plate cell type standby batteries in the conventional vented (types FAP-H and FCP-H) and low-maintenance (types SAP, SBP and SEP) versions. Capacities up to 600 Ah (vented. Table 50.9)... 

Also available in the standard range is the R series of engine-starting standby batteries. These batteries are supplied as single cell containers with capacities up to 384Ah, or as monobloc containers with capacities up to 276 Ah (Table 50.12). 

The case is the largest portion of the container. The case is divided into compartments which hold the cell elements. The cores normally have a mud-rest area used to collect shed soHds from the battery plates and supply support to the element. Typical materials of constmction for the battery container are polypropylene, polycarbonate, SAN, ABS, and to a much lesser extent, hard mbber. The material used in fabrication depends on the battery s appHcation. Typical material selections include a polypropylene—ethylene copolymer for SLI batteries polystyrene for stationary batteries polycarbonate for large, single ceU standby power batteries and ABS for certain sealed lead—acid batteries. 

Stationary batteries serve predominantly as an emergency power supply, i.e., they are on continuous standby in order to be discharged for brief periods and sometimes deeply, up to 100 percent of nominal capacity, in the rare case of need. The following profile of requirements for the separator thus arises very low electrical resistance, low acid displacement, no leaching of substances harmful to float-... 

A more recent paper considered the use of a hybrid power supply for powering autonomous microsen-sors. ° Such devices are similar to the dust mote pictured in Figure 1 and described in the Introduction. This hybrid power supply combined a solar cell to meet standby requirements and to charge the battery, which was the microfabricated Ni—Zn battery described in section 3.2. The authors also showed that if the battery alone was to serve as the power source, the footprint would be substantially larger, over 12 cm . The hybrid device was constructed and some feasibility experiments were carried out, but no actual devices were powered. 

In a different type of RUPS system, during loss of normal power the AC motor is supplied from a battery bank by means of an inverter (Figure 2.19). The batteries are kept charged by the normal power source. The motor is powered from the batteries until the batteries become depleted. In some applications, standby generators are used to supply the battery bank in case of loss of normal power. Other combinations are used to provide uninterrupted power to critical loads, but we will not attempt to review all the available technologies. It is sufficient to point out that low-frequency disturbances are effectively mitigated using one of the means mentioned in this section. 

Stationary battery (cell) — Rechargeable -> batteries designed to be located at a fixed place. Stationary batteries are used mainly for uninterruptible power supplies (UPS) and standby applications. These cells are usually designed for high reliability and very long -> cycle life under shallow depth of discharge (DOD) conditions. The common chemical systems utilized for the production of stationary batteries are the -> lead-acid and -> nickel-cadmium batteries. Less common, and more futuristic is the - sodium-sulfur battery designed for KW and... 

A pharmaceutical plant can obtain emergency or standby electrical power from generators, rechargeable batteries, and in rare cases from a separate utility service. Uninterruptible power supplies, central storage battery system, and unit equipment all use rechargeable batteries for their emergency source of power. 

The converse of taking electricity off the grid is supplying electricity to the grid. Building owners have used standby generators, fuel cells, and battery banks to provide backup electric power to applications that are especially sensitive to disruption. These include hospitals, attended care facilities and health clinics, banks and credit data processing centers, and even homeowners. 

The majority of VRLA batteries produced today are used in standby applications to provide a reliable source of power in the event of failure of the mains supply. Discharges are infrequent and the batteries are maintained by float charging at a preset voltage. For example, European practice is to use parallel strings (usually 48 V) across a 54.5 V supply (2.27 V per cell). Adequately designed new cells, after conditioning and free of impurities, have a float current of < 1 mA per Ah at 20°C. 

V batteries in the PQ2000 unit. The full-scale PQ2000 switches from standby to full operation in about one-quarter of a 60-Hz cycle (4.2 ms) and can supply 2MW/2MVA for 10 s. When the utility supply normalizes, load excitation is transferred back to the utility supply. If the disturbance is due to a recloser operation of the utility distribution-line, for example, the entire PQ2000 cycle will be completed in about 3 s. (Utilities use reclosers to open momentarily a feeder-line in the event of a fault on the line. Typically, the recloser is programmed to cycle about three times before it latches open and requires operator intervention.)... 

We observe that almost two thirds of the anomalies involve the reactivity control function (command of control rod positions), the containment (notably dome isolation and reactor building ventilation) and standby supplies (diesel generator sets, batteries and switchboards that they supply). The anomalies concerning sodium only involve eight events... 

Uninterruptible Power Supply TUPS ) means a power supply that provides automatic, instantaneous power, without delay or transients, on failure of normal power. It can consist of batteries or full-time operating generators. It can be designated as standby or emergency power depending on the application. Emergency installations must meet the requirements specified for emergency power. 

The final specification (Table 10.4) is for an emergency power supply for a computer memory this is again a relatively small battery and the prime need is a long shelf life and the ability to work promptly on demand. Possible batteries would include secondary Ni/Cd or sealed Pb/acid or a long-life primary cell such a HgO/Cd or certain lithium cells. Table 10.4 Specification for standby supply to volatile computer memories. ... 

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