Electrical Test and Electric Motors

Fluorescent tubes
These were first introduced in 1938. In these tubes, an electrical discharge causes electrons to collide with ions of mercury vapor, resulting in ultraviolet radiation due to energization of the mercury atoms. The fluorescent material, which covers the inside of the tubes, then transforms this radiation into visible light.

Fluorescent tubes dissipate less heat and have a longer service life than incandescent lamps, but they do need an ignition device called a “starter” and a device to limit the current in the arc after ignition. This last device called “ballast” is usually a choke placed in series with the arc. The constraints affecting this ballast are detailed in the rest of the document.

Compact fluorescent lamps
These are based on the same principle as a fluorescent tube. The starter and ballast
functions are provided by an electronic circuit (integrated in the lamp) which enables the use of smaller tubes folded back on themselves.

Compact fluorescent lamps were developed to replace incandescent lamps: they offer significant energy savings (15 W against 75 W for the same level of brightness) and an increased service life (8,000 hrs on average and up to 20,000 hrs for some).

Standard compact fluorescent lamps take a little longer to ignite and their service life is reduced according to the number of times they are switched on. So, if the ignition frequency is multiplied by 3, the service life is reduced by a ratio of 2.