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Thread: Current control

  1. #1
    Diamond Member adrianh's Avatar
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    Current control

    I have a small electrical furnace. The machine is basically a temperature controller connected to a contactor which connects to an element. The problem is that the when the element turns on it draws 15A continuously until the thermocouple shuts it down.

    What would be the best way to limit this to say 5A or 10A withou wasting energy or creating additional heat?

    Is there an industrial current limit unit available?
    How easily someone is offended is directly proportional to how stupid they are.
    ~GS Elevator

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    Remove the big element, fit 2 or 3 seperate elements with a selector switch, 1 and 2 and 3, which would give you 5 - 10 - 15 amps.

    I dont know on any current limiting device for big elements. I have used a light dimmer for a cutter device (special wire) for polystyrene, to control the temperature.

    I can find out from people in the know if you dont come right.

  3. #3
    Diamond Member adrianh's Avatar
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    The element is a simple wire twised together in the correct shape.
    How easily someone is offended is directly proportional to how stupid they are.
    ~GS Elevator

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    Diamond Member Justloadit's Avatar
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    The easiest would be to use a lamp dimmer in series with the element. Ensure the dimmer is rated for the current. Turn the knob and set at the desired setting.
    Victor - Knowledge is a blessing or a curse, your current circumstances make you decide!
    Solar and LED lighting solutions - www.microsolve.co.za

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    Andrian's element is around 4000 watts give or take a few.

    Where is Andy ?

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    You can instal a thyristor drive and install a hockey puck on the thermocouple to have a 4-20mA output to control the drive

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    Diamond Member adrianh's Avatar
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    @justloadit - I'll see if I can find one that can cope with the current.
    How easily someone is offended is directly proportional to how stupid they are.
    ~GS Elevator

  8. #8
    Diamond Member Justloadit's Avatar
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    Hi Adrian,

    Stick a big heatsink on the triac, being a resistive load, there should be no problem to do this. Don't forget to isolate the triac tab.
    Victor - Knowledge is a blessing or a curse, your current circumstances make you decide!
    Solar and LED lighting solutions - www.microsolve.co.za

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    Diamond Member adrianh's Avatar
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    I contacted R & D Electronics in Cape Town who told me that I have to order from their suppler Bellco. Bellco told me that the don't stock the item but that R & D would have to build it specially. Bellco said that they would come back with a price and lead time.... 3 hours ago....

    I'm not holding my breath....
    How easily someone is offended is directly proportional to how stupid they are.
    ~GS Elevator

  10. #10
    Diamond Member adrianh's Avatar
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    The 5KW dimmer is going to set me back R980. I'm going te get it tomorrow and see how it goes.
    How easily someone is offended is directly proportional to how stupid they are.
    ~GS Elevator

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