Page 1 of 2 12 LastLast
Results 1 to 10 of 12

Thread: Current control

Hybrid View

Previous Post Previous Post   Next Post Next Post
  1. #1
    Diamond Member
    Join Date
    Mar 2010
    Location
    Cape Town
    Posts
    6,329
    Thanks
    426
    Thanked 978 Times in 795 Posts

    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?

  2. #2
    Diamond Member
    Join Date
    Apr 2010
    Location
    planet earth
    Posts
    3,943
    Thanks
    153
    Thanked 317 Times in 287 Posts
    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
    Join Date
    Mar 2010
    Location
    Cape Town
    Posts
    6,329
    Thanks
    426
    Thanked 978 Times in 795 Posts
    The element is a simple wire twised together in the correct shape.

  4. #4
    Diamond Member Justloadit's Avatar
    Join Date
    Nov 2010
    Location
    Johannesburg
    Posts
    3,479
    Thanks
    134
    Thanked 695 Times in 593 Posts
    Blog Entries
    1
    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 pumping, Solar Geyser & Solar Security lighting solutions - www.microsolve.co.za

  5. #5
    Diamond Member
    Join Date
    Apr 2010
    Location
    planet earth
    Posts
    3,943
    Thanks
    153
    Thanked 317 Times in 287 Posts
    Andrian's element is around 4000 watts give or take a few.

    Where is Andy ?

  6. #6
    Full Member
    Join Date
    Sep 2012
    Location
    Centurion
    Posts
    39
    Thanks
    2
    Thanked 3 Times in 3 Posts
    You can instal a thyristor drive and install a hockey puck on the thermocouple to have a 4-20mA output to control the drive

  7. #7
    Diamond Member
    Join Date
    Mar 2010
    Location
    Cape Town
    Posts
    6,329
    Thanks
    426
    Thanked 978 Times in 795 Posts
    @justloadit - I'll see if I can find one that can cope with the current.

  8. #8
    Diamond Member Justloadit's Avatar
    Join Date
    Nov 2010
    Location
    Johannesburg
    Posts
    3,479
    Thanks
    134
    Thanked 695 Times in 593 Posts
    Blog Entries
    1
    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 pumping, Solar Geyser & Solar Security lighting solutions - www.microsolve.co.za

  9. #9
    Diamond Member
    Join Date
    Mar 2010
    Location
    Cape Town
    Posts
    6,329
    Thanks
    426
    Thanked 978 Times in 795 Posts
    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....

  10. #10
    Diamond Member
    Join Date
    Mar 2010
    Location
    Cape Town
    Posts
    6,329
    Thanks
    426
    Thanked 978 Times in 795 Posts
    The 5KW dimmer is going to set me back R980. I'm going te get it tomorrow and see how it goes.

Page 1 of 2 12 LastLast

Similar Threads

  1. Replies: 3
    Last Post: 28-Nov-12, 04:06 PM
  2. Calculating current based on start up or running?
    By BlueArc in forum Electrical Contracting Industry Forum
    Replies: 2
    Last Post: 04-Oct-12, 10:46 AM
  3. [Opinion] AC voltage / current data logger
    By murdock in forum Technology Forum
    Replies: 6
    Last Post: 18-May-11, 11:25 AM
  4. . Current Market Conditions In The Tradeshow Business
    By donaldcarter55 in forum Business Finance Forum
    Replies: 1
    Last Post: 29-Mar-10, 10:10 PM
  5. electrical over current protection
    By mikilianis in forum Electrical Contracting Industry Forum
    Replies: 8
    Last Post: 21-Jan-10, 03:30 AM

Did you like this article? Share it with your favourite social network.

Did you like this article? Share it with your favourite social network.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •