Editing Fluorescent lamp (section)

====Preheating====
[[File:Fluorescent Light.svg|thumb|A ''preheat'' fluorescent lamp circuit using an automatic starting switch. A: Fluorescent tube, B: Power (+220 volts), C: Starter, D: Switch (bi-metallic thermostat), E: Capacitor, F: Filaments, G: Ballast]]
[[File:Fluorescent lamp-electronic ballast starter-movie VNr°0001.ogv|thumb|left| Starting a preheat lamp. The automatic starter switch flashes orange each time it attempts to start the lamp.]]
Preheating, also called switchstart, uses a combination [[electrical filament|filament]]–[[cathode]] at each end of the lamp in conjunction with a mechanical or automatic ([[Bimetallic strip|bi-metallic]]) switch (see circuit diagram to the right) that initially connect the filaments in series with the ballast to preheat them; after a short preheating time the starting switch opens. If timed correctly relative to the phase of the supply AC, this causes the ballast to induce a voltage over the tube high enough to initiate the starting arc.<ref name=philipsapp>{{cite book|chapter=Chapter 8. Lighting|title=Power Semiconductor Applications|chapter-url= http://www.nxp.com/documents/application_note/APPCHP8.pdf|archive-url= https://web.archive.org/web/20091122114429/http://www.nxp.com/documents/application_note/APPCHP8.pdf|url-status=dead|archive-date=22 November 2009|access-date=22 November 2009|publisher=Philips Semiconductors}}</ref> These systems are standard equipment in 200–240&nbsp;V countries (and in the United States lamps up to about 30&nbsp;watts).

[[File:Starterp.jpg|thumb|left|A ''preheat'' fluorescent lamp "starter" (automatic starting switch)]]
Before the 1960s, four-pin thermal starters and manual switches were used.{{Citation needed|date=June 2013}} A [[glow switch starter]] automatically preheats the lamp cathodes. It consists of a normally open [[bi-metallic strip|bi-metallic]] switch in a small sealed [[gas-discharge lamp]] containing inert gas (neon or argon). The glow switch will cyclically warm the filaments and initiate a pulse voltage to strike the arc; the process repeats until the lamp is lit.  Once the tube strikes, the impinging main discharge keeps the cathodes hot, permitting continued electron emission. The starter switch does not close again because the voltage across the lit tube is insufficient to start a glow discharge in the starter.<ref name=philipsapp/>

[[File:Pulsestarter.JPG|thumb|Electronic fluorescent lamp starters]]

With glow switch starters a failing tube will cycle repeatedly.  Some starter systems used a thermal over-current trip to detect repeated starting attempts and disable the circuit until manually reset.

A [[power factor]] correction (PFC) [[capacitor]] draws leading current from the mains to compensate for the lagging current drawn by the lamp circuit.<ref name=philipsapp/>

'''Electronic starters''' use a different method to preheat the cathodes.<ref name="electrostart">{{cite web|title=Datasheet of typical electronic starter (not fast start), with detailed explanation of operation|url=http://www.tabelek.co.uk/datasheets/UM2-UM3-Datasheet.pdf|access-date=2011-04-08 |archive-date=2012-03-22 |archive-url=https://web.archive.org/web/20120322120421/http://www.tabelek.co.uk/datasheets/UM2-UM3-Datasheet.pdf|url-status=live}}</ref> They may be plug-in interchangeable with glow starters. They use a semiconductor switch and "soft start" the lamp by preheating the cathodes before applying a starting pulse which strikes the lamp first time without flickering; this dislodges a minimal amount of material from the cathodes during starting, giving longer lamp life.<ref name="philipsapp" /> This is claimed to prolong lamp life by a factor of typically 3 to 4 times for a lamp frequently switched on as in domestic use,<ref name="faststart">{{cite web|title=Datasheet of typical fast start electronic starter, with detailed explanation of operation|url=http://www.tabelek.co.uk/datasheets/300C-Datasheet.pdf|access-date=2011-04-08 |archive-date=2012-03-22 |archive-url=https://web.archive.org/web/20120322120454/http://www.tabelek.co.uk/datasheets/300C-Datasheet.pdf|url-status=live}}</ref> and to reduce the blackening of the ends of the lamp typical of fluorescent tubes. While the circuit is complex, the complexity is built into an [[integrated circuit]] chip. Electronic starters may be optimized for fast starting (typical start time of 0.3 seconds),<ref name="faststart" /><ref name="type300c">{{cite web|title=Electronic Tube Starter 300C Fastlux for fluorescent strip lights|url=http://www.tabelek.co.uk/product-300C-fastlux-electronic-fluorescent-tube-starter.php|website=www.tabelek.co.uk|access-date=2019-04-26 |archive-date=2019-01-08 |archive-url=https://web.archive.org/web/20190108100850/http://www.tabelek.co.uk/product-300C-fastlux-electronic-fluorescent-tube-starter.php|url-status=live}}</ref> or for most reliable starting even at low temperatures and with low supply voltages, with a startup time of 2–4 seconds.<ref name="um2">{{cite web|title=Soft Start Electronic Starter for fluorescent tubes the UM2 Multi Pulse|url=http://www.tabelek.co.uk/product-um2-multipulse-electronic-fluorescent-tube-starter.php|website=www.tabelek.co.uk|access-date=2019-04-26 |archive-date=2019-04-23 |archive-url=https://web.archive.org/web/20190423140214/http://www.tabelek.co.uk/product-um2-multipulse-electronic-fluorescent-tube-starter.php|url-status=live}}</ref> The faster-start units may produce audible noise during start-up.<ref>{{cite web| title=Fast electronic starters for fluorescent lights| date=20 June 2004<!--from page source-->| quote=All three of the 'FAST' (< .5 seconds) starter brands caused an audible 'BURRRRRRRP' noise in some light fittings as they started and this is an inherent problem caused by their use of the faster 'DC' heating. It is worse with higher wattage tubes and if there is any loose metal in the light fitting.| website=users.tpg.com.au| url=http://users.tpg.com.au/pschamb/light.html| access-date=25 February 2023| archive-date=2012-11-04 | archive-url=https://web.archive.org/web/20121104034555/http://users.tpg.com.au/pschamb/light.html| url-status=live}}</ref>

Electronic starters only attempt to start a lamp for a short time when power is initially applied, and do not repeatedly attempt to restrike a lamp that is dead and unable to sustain an arc; some automatically stop trying to start a failed lamp.<ref name="electrostart" /> This eliminates the re-striking of a lamp and the continuous flashing of a failing lamp with a glow starter. Electronic starters are not subject to wear and do not need replacing periodically, although they may fail like any other electronic circuit. Manufacturers typically quote lives of 20 years, or as long as the light fitting.<ref name="type300c" /><ref name="um2" />