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Resilience of lighting to voltage fluctuations

Former Community Member
Former Community Member

Came home this evening to find the house in darkness. Got the text from Western Power just as I turned into my road. Problem: HV fuse blown on one phase (probably due to trees as they don't appear to be cutting them back as regularly). Despite this there was still some power: when checked, my mains supply was running at about 80V. Switched on hall light (LED), got interesting disco effect. Landing light (also LED) stayed off. Switched on alcove lights in living room (tungsten filament) and got red glow. DAB radio in kitchen worked perfectly! (Plug type PSU, switch mode?). Other LED lights didn't play ball either except for 3-LED flex light over the bed (worked but dimmer than usual) and workbench anglepoise lamp (12W LED rated 220-240V) which worked perfectly!

From this I assume that most of my LED lighting probably has fairly simple driver electronics while some lamps are regulated better and more tolerant of wide voltage ranges.

  • 0

    If you want to know about the innards of LED lamps, see a seemingly unlimited number of teardowns of them on the “bigclivedotcom” YouTube channel.

    Some have a switch mode power supply.

    Others use a simple “capacitive dropper” - a capacitor wired in series with the LEDs to add impedance and limit the current.  It's like putting a resistor in series, but without generating lots of heat.

  • 0

    Almost all LED lamps except the very small ones that are one watt or less use switched mode power supplies these days.

    They vary a lot as to what voltage range they can accept. Those designed for only the European market tend to accept from about 190 volts up to about 260 volts. A nominal 220 volt supply could be as low as 198 at the point of supply, and as low as 190 volts at the point of use.

    The UK supply can be as high as 255 volts with PV backfeeding. Parts of India are still 250 volts nominal, and a bit more in practice.

    Other lamps are intended for world wide use, lower limit of 85 volts for Japan to allow for 100 volts nominal that is 90 volts at point of supply and 85 volts at point of use. Upper limit as above.

    And of course some lamps might operate on a voltage a little lower than specified.

    In the USA LED lamps are available that accept from 100 volts up to 310 volts. To allow use from 120 volt, 208 volt, 240 volt, or 277 volt circuits.

    Most types will accept a SLIGHTLY lower voltage on 60 cycles than on 50 cycles.

     

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