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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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    The tubes run fine on DC , as will the CFL tubes, if you remove the electronics, and go direct to the tube itself.

    The old iron cored ballasts are not happy on DC, or indeed on anything that is not a good 50Hz as they rely on the inductance to provide the dropping impedance.

    I have run a 40w tube with a 60W lamp in place of the choke ballast, and it's not quite right, but it runs, resistance ballasting like that is possible, but lossy. (As a child I have seen light weight fittings with a filament lamp ballast, sold for hanging from the ceiling, from the 1960s ' soon power will be too cheap to meter' era.)  Resistance ballast is of course frequency independant, and  therefore will be good from DC to many kHz, though low freq AC tends to lead to flicker and flame-out requiring a re-strike. You can run them from an audio power amplifier via a mains transformer used backwards, but it is worth supplying at least one heater supply that is permanent.

    On DC the striking circuit needs more thought, and has more in  common with an electric fence pulser or a car ignition.

    May modern electronic 'ballasts' are designed to run on DC anyway,. as the first thing they do is rectify the mains coming in, and then chop it up again at a supersonic frequency that goes to the tube - the advantage is the £2 of electronics uses a far smaller transformer at 30KHz or whatever, compared to the 50Hz part, and the saving on the copper and iron is worth it, as a bonus the design can be made to better adjust to varying mains voltages , and can be more efficient. 

    I can well believe that such fittings may well have varying run-done times as the power is removed, and the internal smoothing capacitor goes flat.

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    The tubes run fine on DC , as will the CFL tubes, if you remove the electronics, and go direct to the tube itself.

    The old iron cored ballasts are not happy on DC, or indeed on anything that is not a good 50Hz as they rely on the inductance to provide the dropping impedance.

    I have run a 40w tube with a 60W lamp in place of the choke ballast, and it's not quite right, but it runs, resistance ballasting like that is possible, but lossy. (As a child I have seen light weight fittings with a filament lamp ballast, sold for hanging from the ceiling, from the 1960s ' soon power will be too cheap to meter' era.)  Resistance ballast is of course frequency independant, and  therefore will be good from DC to many kHz, though low freq AC tends to lead to flicker and flame-out requiring a re-strike. You can run them from an audio power amplifier via a mains transformer used backwards, but it is worth supplying at least one heater supply that is permanent.

    On DC the striking circuit needs more thought, and has more in  common with an electric fence pulser or a car ignition.

    May modern electronic 'ballasts' are designed to run on DC anyway,. as the first thing they do is rectify the mains coming in, and then chop it up again at a supersonic frequency that goes to the tube - the advantage is the £2 of electronics uses a far smaller transformer at 30KHz or whatever, compared to the 50Hz part, and the saving on the copper and iron is worth it, as a bonus the design can be made to better adjust to varying mains voltages , and can be more efficient. 

    I can well believe that such fittings may well have varying run-done times as the power is removed, and the internal smoothing capacitor goes flat.

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