Discharge lamps require special gear to activate the discharge process and also to stabilise operating current and power consumption, such as starters, igniters and ballasts. This type of lamp cannot be operated direct from the mains either because they do not ignite at that voltage or because they would be destroyed if operated at unlimited current.
Electronic and magnetic ballasts
Lamps with electronic ballasts do not require a separate ignition system, as it is integrated in the ballast. In the case of fluorescent lamps with magnetic ballasts, a starter is used for ignition.
High-pressure mercury lamps ignite at mains voltage, whereas high-pressure sodium lamps and metal-halide lamps can only be ignited with the help of a suitable igniter.
A distinction can be made between superimposed pulse igniters, in which the ignition voltage is generated in an integrated high-voltage transformer, and impulsers, which deliver impulses to the ballast to generate the high voltage required. Superimposed pulse igniters are subject to a maximum permissible distance between the lamp and the igniter (e.g. 1.5 m).
Following ignition, high-pressure lamps take a few minutes (up to 10 min.) to reach full luminous flux (run-up period). During this period a higher run-up current flows (up to twice rated current). Once switched off, the lamps can only re-ignite after cooling down for a few minutes (cf. restriking). Immediate restrike is possible with double-ended metal halide lamps and high-pressure sodium lamps fitted with a suitable igniter.