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kit for variable speed drive

Discussion in 'Hobby Electronics' started by Craig Curtin, Sep 20, 2004.

  1. Craig Curtin

    Craig Curtin Guest

    Guys,

    I have a standard 240v AC cicrulating pump which i want to control
    from a PIC - i am looking for a kit or plans to interface the PIC to a
    Variable speed controller.

    Anyone know how this is done or have access to plans ??

    Craig
     
  2. Phil Allison

    Phil Allison Guest

    "Craig Curtin"

    ** Using an electronic variable frequency drive has to be the most absurdly
    expensive option possible for a water pump.

    The smallest model in the Farnell cat costs nearly $1000.




    .............. Phil
     
  3. Craig Curtin

    Craig Curtin Guest

    Sorry maybe i have written this incorrectly then.

    My understanding is that for a standard 240v ac centrifugal pump that
    by varying the frequency of the cycle will vary the speed of the pump.

    I have found reference on the net to a number of solutions for this,
    all of which seemed to be "relatively" simple (i am a Newbie to
    electronics). However none of them looked as if they would cost $1000
    or more ??

    What other way would you do this ??

    Craig
     
  4. Phil Allison

    Phil Allison Guest

    "Craig Curtin"
    ** I would love to see your "simple" variable frequency drive for a
    fractional horsepower 240 volt AC motor. The only ones I know about are full
    of high voltage mosfets, uPs and assorted electronic technology.

    BTW 1. An electronic interface has to interface to some particular
    hing - seems you have the cart firmly in front of the horse.


    BTW 2. Top posting is bad usenet manners and very annoying.



    ............. Phil
     
  5. Prolly be more practical to drive a variable valve on the output of the pump
    but it still wont be cheap.
     
  6. Bushy

    Bushy Guest

    KISS!

    Use 2 smaller pumps and a couple of relays!

    Or a couple of house water tank pressure pumps in parallel. Scale it up or
    down from there to suit your application. If you use a pressure tank, a
    pressure switch and a restriction on the outlet you will maintain a pretty
    steady flow.

    Is there a reason you need to get a more steady flow?

    Hope this helps,
    Peter
     
  7. Craig Curtin

    Craig Curtin Guest

    I want to have a continual variable flow based on temperature sensors
    Starting and stopping pumps is the worst thing you can do for the life
    of them
    This is a hydronic heating application and by using a continuous flow
    some of the issues of thermal bloom can be reduced together with
    improving the longevity of the pump by not continually starting and
    stopping.

    I have been pointed to a NZ site that has a traic that appears to do
    what i want for $65 (so much for Phil Allison and his attitude)

    I will report back once i hear form the company

    Craig Curtin
     
  8. Bottom posting is annoying. Why would i want to read again all of the
    stuff, that the previous has posted? If you need to read it again (if
    your memory doesn't work), then read it. I personally find it pretty
    stupid to bottom post, since it only leads to scrolling the damn page
    down just to see what the next guy answered, thank you very much.
     
  9. Phil Allison

    Phil Allison Guest

    "Craig Curtin"

    ** Triacs do NOT vary the AC frequency but merely chop bits off each half
    cycle to vary the average torque produced by a motor. If the motor is
    loaded fairly heavily, as with a room fan for example, this will cause the
    speed to drop to a lower one. However, you do not have actual *speed*
    control as you would with a "variable frequency drive".

    Beware, a triac "light dimmer" connected to an induction motor can be
    risky - at some setting the triac may decide to operate during one half
    cycle only effectively feeding DC current to the motor which will BURN IT
    OUT.


    BTW The poor attitude is all yours.



    ............... Phil
     
  10. Phil Allison

    Phil Allison Guest

    "Jouni Kaukonen"
    ** Idiot.

    Why would i want to read again all of the

    ** One breaks the post up and responds to the individual ideas / comments
    with replies.


    If you need to read it again (if

    ** Obviously you are someone who DOES NOT reply to other peoples thoughts
    and ideas individually.

    ** YOU** insist on posting pompous, irrelevant speeches instead.

    Top posting is not a method - it is an arrogant attitude.





    ............ Phil
     
  11. **** you too
    What if i don't need to reply individually dumbass.
    You know, logics ain't forbidden in here.
     
  12. To make things more clear to you:
    As i said, what if i had only one question to answer to?
    Craig there replied fully correctly.
    Really which is more annoying, to see the answer right there or to
    scroll down the previous text just to see the answer?
    Use your brains and logic.
    As far as i'm conserned, you don't need to reply, just think for a
    minute there.
     
  13. Phil Allison

    Phil Allison Guest


    ** Point proven.


    ** So YOU** insist on posting pompous, irrelevant speeches instead ???


    ** A foreign idea to you.



    ............ Phil
     
  14. Phil Allison

    Phil Allison Guest

    "Jouni Kaukonen"

    ** Then post under that question - trim it to its essentials if you like.


    ** Nope - he rudely top posted.


    ** Questions come first - answers second.

    Horses first - then carts.


    ** Time for you to try that sometime.



    ** Top posters are mentally defective - they cannot be see that they are
    are out of step and so WRONG.





    ............. Phil
     
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