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Thread: cob led + mini transformer that can operate on 380/400/415v

  1. #1

    Default cob led + mini transformer that can operate on 380/400/415v

    I need a cob style led chip + separate transformer to replace a old LoVo light setup on my surface grinder as the transformer has gone in the lovo housing and I'm on my last low voltage incandescent machine lamp bulb anyway, and the bulb holder is trash too. I run the grinder with suds most of the time, so it has to be low voltage for safety.

    I can site a chip style led transformer inside the lovo housing where the original lovo transformer lived, and have low volt wiring up to the machine light itself and swap out the holder for a led chip using the original wiring, trouble is, the machine has no neutral connection in its wiring closet, and is 3phase. So "mains" voltage into the lovo transformer housing is 400v in this case.

    I've gone through my little cob + transformer stash, and all of them are rated on their label as 100-280v so I imagine feeding one 400v might be detrimental to its short term life let alone a long term one, has anyone found any on the usual sites for the same with 20 or 30w cob led chip but will take higher input voltages without letting the magic smoke out?
    If push comes to shove, I'll add a neutral into the machine itself and use one of these to give me 230v instead, but it means new wiring, plug etc, so if I can just buy the right thing instead it might be easier, plus I have some other machines that could do with the same too.

    Regards
    MrFluffy

  2. #2
    Join Date
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    Missouri
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    What voltage are the machine controls?

    Usually they are not run on 400V. If they are run on a lower voltage, then your issue becomes simpler, start with the lower machine control voltage.
    1601

    Keep eye on ball.
    Hashim Khan

  3. #3

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    The machine itself just has a go and stop contactor which runs 380v, and everything else runs on hydraulics, so not sure I have any low voltages to tap. Digging through stash to see if I can transform the 380 down into something I can feed the cheap cob driver transformers instead as the current option.

  4. #4
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    Well, a 480 to 120V transformer will produce 100V if used with that. Not sure where you are, so some may be more available than others in your location.
    1601

    Keep eye on ball.
    Hashim Khan

  5. #5
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    First I would go for a 24 V circuit, not 115 V.

    24 to 28 Volt, cob LEDs:

    https://www.digikey.com/products/en/...=1&pageSize=25

    480V to 24V transformers:

    https://www.mouser.com/Power/Transfo...former&FS=True

    You will need to rectify the AC transformer output to DC for the best results. And be sure to match the current requirements of the LED you choose to the transformer's rating.

    But I would use a power supply instead of a transformer. With a regulated, DC power supply, you get the exact Voltage needed and they are highly efficient. So your LEDs should last for their rated life. DC power supplies, 24 V:

    https://www.digikey.com/products/en/...=1&pageSize=25

    Good luck.
    Paul A.

    Make it fit.
    You can't win and there is a penalty for trying!

  6. #6
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    That's the reason for using 100/115V..... there are so many regulated supplies that accept that (or 230V, in UK, where the OP may actually be located, IIRC.
    1601

    Keep eye on ball.
    Hashim Khan

  7. #7
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    Quote Originally Posted by Paul Alciatore View Post
    First I would go for a 24 V circuit, not 115 V.

    24 to 28 Volt, cob LEDs:

    https://www.digikey.com/products/en/...=1&pageSize=25

    480V to 24V transformers:

    https://www.mouser.com/Power/Transfo...former&FS=True

    You will need to rectify the AC transformer output to DC for the best results. And be sure to match the current requirements of the LED you choose to the transformer's rating.

    But I would use a power supply instead of a transformer. With a regulated, DC power supply, you get the exact Voltage needed and they are highly efficient. So your LEDs should last for their rated life. DC power supplies, 24 V:

    https://www.digikey.com/products/en/...=1&pageSize=25

    Good luck.
    Current.
    You should be using current regulated or constant current power supply, constant voltage is BAD way to drive those LEDs.

    Some chinese COB boards pack the "integrated smart ic" power supply to same COB board with the leds, but I haven't seen 24v models. Only 110 or 230v input
    https://www.ebay.com/itm/30W50W70W10...FKOyIBCi0tlxnQ

  8. #8
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    Comes to mind that if you use a transformer to begin with, you can end up with an isolated secondary. Even though still a high voltage, like 150vdc after rectification, it has less shock potential. There are cob led decks that have their own current regulator and are designed to run from 110 vac or higher. You have isolated voltage, but still high so maybe it's still a no-starter. But it's pretty simple, just the led deck and the transformer.

    You're likely going to be using the step down transformer anyway, so the next simplest is to add as few parts as possible between the led array and the transformer. How much led power are you thinking about anyway? I don't recall anyone suggesting what wattage level we're dealing with.
    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

  9. #9

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    I have 10,20 and 50w cob led + drivers on the shelf already in 100-280v versions. These come with a separate cob chip and a driver unit, so you can locate the driver inside and feed it "normal" mains voltages, but it emits low volt 24v dc into the cob chip via its wiring.
    I've done a few machine lights with this layout already, locating the driver part inside the machine base with other electrical components & using the existent wiring on the machine between base and lamp and swapping the bulb holder for a heatsink and the cob chip to move from defunct original lovo setups, but this machine is a bit awkward because its 3 phase with no neutral to pick up a 230v single phase feed from to run things. On deeper reflection I may bite the bullet and change the wiring to it and rewire the lockout and plug etc because I also want to eventually fit it with a DRO when funds allow, and that will have the same issues.
    Given how generic and wooly the spec's are on these things are, It may even be possible to feed 380v to something rated at 280v max on its print label and it cope, but ignoring spec's seems like a bad thing in general to get into, even with chinese spec's...

    Holy grail would have been someone who's had the same issue chiming in saying "hey, this brand from xyz can cope with higher input voltages" and it be silk-screened or printed onto the label of them.
    Last edited by MrFluffy; 04-16-2018 at 03:18 AM.

  10. #10
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    If an LED ASSEMBLY is designed to run on a specific Voltage, then a Voltage regulated supply is just fine. We are not talking about naked LEDs here which would operate in current mode and somewhere between 1.5 and 3 Volts. A 24 Volt LED assembly, such as a COB, will have it's own current regulation and be just fine with that Voltage.



    Quote Originally Posted by MattiJ View Post
    Current.
    You should be using current regulated or constant current power supply, constant voltage is BAD way to drive those LEDs.

    Some chinese COB boards pack the "integrated smart ic" power supply to same COB board with the leds, but I haven't seen 24v models. Only 110 or 230v input
    https://www.ebay.com/itm/30W50W70W10...FKOyIBCi0tlxnQ
    Paul A.

    Make it fit.
    You can't win and there is a penalty for trying!

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