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Would a standard fluorescent fitting work on DC

jcm
Would a standard fluorescent fitting work on DC. Of course it would but a certain type most of you have never seen with a balance lamp for starting and changeover switch control. The reason I ask is  at one engineering factory switched off the 3P main  switch to check the mains fuses type and size, the high bay lighting (fluorescents ) did not turn off instantaneous but went out at random . Put it down to a connected capacitor bank supplying voltage. How could that be as the capacitor holding on  voltage would be DC.  That was a long time ago but am sure this situation would be more noticeable now with low wattage LED lighting. his post may not be at all relevant and I am not sure i understand it all, but it happened.    

Bleed resistors , it is my observation when was inspecting main switchboards at various factories (insurance inspections) that some resistors  on capacitors were burnt out or missing or one leg of the resistor sticking up in mid air. The can ones all you could look for if any are pregnant or the proper name any with top hats, don't know about the bleed resistors on them.  


jcm

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    A fluorescent light can be used on mains voltage DC and this was done back in the days of DC mains, or on board ships with DC supplies.

    The circuit was similar to a standard switchstart  lamp circuit but with the addition of a dropper resistance in series with the choke. This dropper resistance sometimes took the form of a special incandescent lamp, these are no longer manufactured AFAIK.

    With DC passed through the lamp, the mercury vapour tended to migrate to one end of the lamp and this resulted in only one end lighting correctly and the total light being much reduced. This had to be counteracted by reversing the supply polarity periodically. Special light switches were manufactured for this purpose. These were rotary switches with two "on" positions and two "off" positions, each of the "on" positions had a different polarity. Since the switch had a ratchet action and could only be turned clockwise, the supply polarity was automatically reversed each time the lights were turned on.


    A switchstart fluorescent lamp circuit Without this dropper resistance wont work on DC mains, the current would be excessive and soon destroy the choke or the lamp. It CAN remain lit for a second or two from a charged PFC capacitor.


    A more modern fluorescent light would have an electronic ballast, these often work fine on a DC supply and some types can be used to provide emergency lighting from a central battery system. This battery usually needs to have a higher voltage than the AC mains. Often about 300 volts to 350 volts DC is needed for an electronic ballast primarily designed for 230/240 volts AC. Such a light will also stay lit briefly from a charged PFC capacitor.


    Alternatively, in the circumstances reported by the O/P the lights might have remained lit for a few seconds due to the presence of an AC supply, this being obtained from one or more induction motors that generated briefly as they ran down after turning off the mains.



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    A fluorescent light can be used on mains voltage DC and this was done back in the days of DC mains, or on board ships with DC supplies.

    The circuit was similar to a standard switchstart  lamp circuit but with the addition of a dropper resistance in series with the choke. This dropper resistance sometimes took the form of a special incandescent lamp, these are no longer manufactured AFAIK.

    With DC passed through the lamp, the mercury vapour tended to migrate to one end of the lamp and this resulted in only one end lighting correctly and the total light being much reduced. This had to be counteracted by reversing the supply polarity periodically. Special light switches were manufactured for this purpose. These were rotary switches with two "on" positions and two "off" positions, each of the "on" positions had a different polarity. Since the switch had a ratchet action and could only be turned clockwise, the supply polarity was automatically reversed each time the lights were turned on.


    A switchstart fluorescent lamp circuit Without this dropper resistance wont work on DC mains, the current would be excessive and soon destroy the choke or the lamp. It CAN remain lit for a second or two from a charged PFC capacitor.


    A more modern fluorescent light would have an electronic ballast, these often work fine on a DC supply and some types can be used to provide emergency lighting from a central battery system. This battery usually needs to have a higher voltage than the AC mains. Often about 300 volts to 350 volts DC is needed for an electronic ballast primarily designed for 230/240 volts AC. Such a light will also stay lit briefly from a charged PFC capacitor.


    Alternatively, in the circumstances reported by the O/P the lights might have remained lit for a few seconds due to the presence of an AC supply, this being obtained from one or more induction motors that generated briefly as they ran down after turning off the mains.



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