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Most forms of uninterruptible power supply (UPS) can be either powered by battery or flywheel energy. These are ready for immediate use at the instant that the mains electricity fails, but the relatively small and finite amount of stored energy they contain makes them suitable for short periods of use, typically in the order of a few dozen minutes to a couple of hours depending on the actual load.
The run-time for a battery-operated UPS depends on the type and size of batteries and rate of discharge, and the efficiency of the inverter. The total capacity of a lead–acid battery is a function of the rate at which it is discharged, which is described as Peukert's law. Manufacturers supply run-time rating in minutes for packaged UPS systems.
Resistive/reactive load banks may be used for testing turbines, switchgear, rotary UPS, generators and UPS systems. They can also be used for integrated system testing of utility substation protection systems, particularly for more complex relays like distance, directional overcurrent, power directional and others.
is the actual time to discharge the battery (in hours). Using the above example, if a battery rated for 100 ampere-hours at a 20-hour rate has a Peukert constant of 1.2 and is discharged at a rate of 10 amperes, it would be fully discharged in time 20 ( 100 10 ⋅ 20 ) 1.2 {\displaystyle 20{\left({\frac {100}{10\cdot 20}}\right)^{1.2}}} , which ...
Telephone system central offices contain large battery systems to provide power for customer telephones, telephone switches, and related apparatus. [2] Terrestrial microwave links, cellular telephone sites, fibre optic apparatus and satellite communications facilities also have standby battery systems, which may be large enough to occupy a separate room in the building.
Auxiliary power is electric power that is provided by an alternate source and that serves as backup for the primary power source at the station main bus or prescribed sub-bus. An offline unit provides electrical isolation between the primary power source and the critical technical load whereas an online unit does not.
A 200 kW Caterpillar diesel generator set in a sound attenuated enclosure used as an emergency backup at a sewage treatment substation in Atlanta, United States. A diesel generator (DG) (also known as a diesel GenSet) is the combination of a diesel engine with an electric generator (often an alternator ) to generate electrical energy . [ 1 ]
Standby generators. A standby generator is a back-up electrical system that operates automatically. [1] Within seconds of a utility outage an automatic transfer switch senses the power loss, commands the generator to start and then transfers the electrical load to the generator.