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There is a type of bulb in the market nowadays that detects load-shedding! I mean it keeps lighting after load-shedding. But my curiosity is if I turn off the switch of the bulb, it might have detected that load-shedding has occurred, but it doesn't! How does exactly it detects electricity outage! I want to know the electrical working behind it.

[EDITED]

Here is a video of that product (not exactly mine, but similar) https://www.youtube.com/watch?v=T9yfgc3FpW8

I'm from Bangladesh, yep here load-shedding means turning off in a grid for a short period of time.

My Building has no special electrical connection.

DG_
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  • They mention some "proprietary Grid&Switch sensor technology", which is patent pending. Have you tried it yourself? When I heard about it it made me somewhat skeptical. Especially they claim you can control the bulb with the switch even during outage, which sounds like magic to me if there is no extra components hidden somewhere. – Eugene Sh. Jan 08 '19 at 18:15
  • Nope, I haven't tried that. The only thing is written on the pack of that bulb is "ECO Control" I don't even know what that meant. – DG_ Jan 08 '19 at 18:18
  • Load shedding may well be associated with slight reductions in supply frequency. And I guess it could have some nano-power circuits that rely on capacitive pickup in the supply wire to keep a processor going. – Finbarr Jan 08 '19 at 18:22
  • They have some video here https://www.cepro.com/article/now_thats_a_smart_light_bulb but on 1:14 it looks like the plug he is using is not the plug of the switched splitter. So I would call it a scam unless seeing it myself or hearing from someone I trust. – Eugene Sh. Jan 08 '19 at 18:22
  • It must have an internal battery backup.. clever ehm – Tony Stewart EE75 Jan 08 '19 at 18:25
  • But trust me, there's no special switch in my room, they are all old modeled normal natural switches on the switchboard. What I think, there is sensor workings behind it. But also it is a great mystery what happens in an electricity outage is not equal to the switch off state! – DG_ Jan 08 '19 at 18:26
  • @SunnyskyguyEE75 It definitely has it. The question is how it can distinguish switch off from power outage. – Eugene Sh. Jan 08 '19 at 18:26
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    @DG_: Please edit your question to add a link to a datasheet for the device in question so that the rest of us understand what you are talking about. You might also explain what "load shedding" is and in what country it is used. I'm guessing that your supplier or building manager switches off supply to your building in periods of high demand. – Transistor Jan 08 '19 at 18:34
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    So from this review and from the reviews on amazon it appears to work, but not as perfect as advertised. One limitation common for these is that it can only work in a fixture which has a single bulb on a switch. Which makes me think that the bulb is somehow modulating some signal on the wire s and can detect closed circuit. Update - looking on the duplicate that's it. – Eugene Sh. Jan 08 '19 at 18:35
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    @EugeneSh. my guess would be that, since that is the dominant noise in any household, the thing simply checks for 50 Hz being picked up with a small coil, or simply on the wire. If there's 50 Hz but no power on the mains, switch is off. Is there's beautiful silence on the aether, then there's a power outage? – Marcus Müller Jan 08 '19 at 18:38
  • @MarcusMüller That would be the first though, but they demonstrate it by "simulating" outage by unplugging from the wall. – Eugene Sh. Jan 08 '19 at 18:40
  • The clue here is it won't work if other loads on same circuit which can absorb impulses from grid load switch. – Tony Stewart EE75 Jan 08 '19 at 18:44
  • @DaveTweed yes and I see I gave a better answer than yours in one of those posts – Tony Stewart EE75 Jan 08 '19 at 18:55
  • Like this ? https://www.ikea.com/us/en/catalog/products/60440888/ – Hilmar Jan 08 '19 at 20:59
  • I'm sure there was another question on here about these already. The conclusion was that they basically sense the resistance of the supply. Resistance and no voltage -> switch is off. No resistance and voltage -> power is on, light up and recharge battery. No resistance and no voltage -> power is out, light up using the battery power. – user253751 Jan 09 '19 at 04:14

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