DALI current draw

Discussion in 'General Discussion' started by tigerforce, Aug 21, 2008.

  1. tigerforce

    tigerforce

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    Hi

    Does anyone know if the DALI gateway has a currnet draw when connected to a DALI network. I realise that it has a 32ma draw on the C-Bus network & is optically isolated but cannot find any information on whether their is a load on the DALI network.

    Any comments appreciated.

    Cheers
     
    tigerforce, Aug 21, 2008
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  2. tigerforce

    Newman

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    All DALI devices have some current sink when connected to the network. In the case of the C-Bus DALI gateway the sink current is less than 2mA in receiving mode, which is part of the DALI specification.

    DALI units communicate by shorting out the DALI network briefly to send data bits and trusting in the ~250mA current limiting in the power supply to prevent devices getting fried. That's why you can't use a regular DC supply for DALI devices.
     
    Newman, Aug 22, 2008
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  3. tigerforce

    tigerforce

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    Thanks Newman.

    Didin't think it would be much.
     
    tigerforce, Aug 22, 2008
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  4. tigerforce

    ashleigh Moderator

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    Be very very careful not to put too many DALI power supplies onto your DALI network.

    That bit about shorting the DALI bus and relying on current limiting in the power supply... well... if you put a few power supplies in parallel (clip a few onto the same DALI bus) then you might just end up letting the smoke out of the ballasts, and that will be expensive. They don't work when the smoke is allowed out.
     
    ashleigh, Aug 22, 2008
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  5. tigerforce

    Newman

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    It is part of the DALI specification that only 1 ballast is allowed per DALI universe.
     
    Newman, Aug 22, 2008
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  6. tigerforce

    ashleigh Moderator

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    I think you mean 1 power supply...

    But yes...

    you should not do it.

    Just cos the standard says so does not mean it will be do.

    Be vewy vewy careful that you don't use more than 1.
     
    ashleigh, Aug 22, 2008
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  7. tigerforce

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    Er, yes... 1 power supply per DALI universe.
     
    Newman, Aug 25, 2008
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  8. tigerforce

    samluo

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    I think any device on DALI bus should draw less than 2ma/unit usually.
     
    samluo, Nov 3, 2009
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