Emergency power supplies provide the electrical energy to feed necessary safety installations upon failure or voltage drop of the general power supply. The changeover to emergency power supply must occur once the general power supply voltage has dropped by more than 15% over a time period longer than 0.5s. At more than 85% of rated voltage, the changeover back to mains operation must occur within 1 minute.
Standby electric sources
Emergency power supplies include:
Individual battery, maintenance-free with charging, changeover and control devices as well as deep discharge protection, for a maximum permissible number of two safety or escape sign luminaires. Individual battery systems must comply with EN 60598-2-22.
Group battery, maintenance-free with charging and control devices for safety installations, permissible for a maximum of 300 W over an operating duration of 3 hours/900W over an operating duration of one hour.
Central battery with charging, changeover and control devices as well as deep discharge protection, permissible without performance restrictions for the entire safety installation. Battery-operated central power supply systems must comply with EN 50272-2.
Power stand-by unit consisting of a diesel engine and a generator with a changeover period of 15 s. maximum. Reciprocating internal combustion engines to power AC generators must be constructed according to ISO 8528-12.
Rapid stand-by unit with a changeover period of 0.5 s. maximum. Here, an energy storage serves for short-term supply of consumers and to start the power stand-by unit.
An immediate stand-by engine is a power generation unit without changeover period. An energy storages supplies consumers and an electrical engine short-term to rapidly start the engine of the power stand-by unit.
Networks with special protection feature two independent feeds for safety installations.
The operation of lighting installations via power generation units or specially protected networks is possible if the electrical parameters (voltage, frequency) conform to the luminaires’ nominal operating data. In case of doubt the manufacturer should be consulted.