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  1. #1
    Join Date
    Mar 2007
    Posts
    356

    Default Power factor correction

    Can someone explain how this works on a syncro 250, i understand it does not actually save you any money on the meter, i dont really care about that, im looking at it for the ability to run a smaller breaker (i have a very small service at my home (70a) and even a 60a for the welding machine is pusshing it)

    im just a little fuzzy on the fact that yes, it draws less current while welding, but it draws the same current while idle (or more???) ? and is this current while idle actually running the meter ? because i would imagine that it would run the power bill pretty high just sitting idle, and not only that, if the machine were drawing 50 amps while idel that could cause some issues, (run the chop saw and blow the mains ?)

    i have gas heat and gas water, my only other main draws are the dryer and the stove, so keeping the electric draw low in the house while welding isnt a problem

    would i be better off without the correction caps and just limit the machine to say 200 amps?

    i realise the dynasty machine would be the better option for my low avail input power i have, however i would like the explore all options first, and as this is a rental property i have no plans of being here for the rest of my life and would hate to be limited later on by a smaller machine (the day will come when i buy a house, lol)

    one of the other reasons im looking toward a larger machine is because im used to running hot and fast in a production enviroment, and when the day comes that i have the avail amperage to run a 250 flat out i will, for now i can live with limiting the machine to 200amps ish

    sorry for the long post, but your guy's input would be apreciated
    mm210
    maxstar 150

  2. #2
    Join Date
    Oct 2004
    Location
    Edmonton, Alberta
    Posts
    7,833

    Default

    Basically just set of capacitors that stores energy to boost power for the main transformer, thereby dropping incomming current load. A 70 amp breaker would probably be fine, as you may never get to full machine load,, added as well to the breakers design delay.

    The Dynasty is a way better machine though....

  3. #3
    Join Date
    May 2007
    Posts
    539

    Default

    here is a link to some definitions: (third paragraph)

    http://www.lmphotonics.com/pwrfact.h...FQeHgQodEWB7RQ

    speaks primarily to motor correction.

    what about a dynasty 350? only requires 43amps at 230volt. (little bit pricey)

    I'm not an EE, (two years of ET) but, at idle the machine cannot draw what the welding draw is. If I understand the correction factor, it corrects the phase to reduce loss, ie makes it more efficient, and uses what is available. Their is no free lunch.

    Are you on 50 or 60hz?

  4. #4
    Join Date
    Mar 2007
    Posts
    356

    Default

    60hz

    a dynasty 350 would fit the bill perfectly, but there is no way i could justify the huge sticker price, dont forget im in canada, that sucker is probably 5500 ish with no accessories

    what im really wondering about the power factor is idel current, like if this sucker is drawing say 55 amps just sitting there, i go to cut something with the chop saw, and someone else is grinding with a 12a grinder im thinkin its gonna pop the breaker, now if someone goes to use a chop saw or some other high amperage tool while im welding and it pops the breaker no big deal, but if this thing is going to reduce my productivity while NOT welding, thats a serious issue

    now mabye i should note the machine will used for mainly tig, i understand that has a lower input for specified output than stick, but i wonder if the reduction in input power is enough to be able to run the machine at 200amps on a 50-60a breaker without the power caps

    some reasons the sy250 wins over the dy200 for me is that with 20% duty at the top end of the dy200 i can very easily see me hitting the duty cycle on a regular basis, aswell as i never use the pulsar, not even when down to 22g stainless, the ajustable ac freq sounds like a real nice feature but i have years on the syncrowave machines and dont see myself playing around with that feature

    dont take that as me saying i dont think the dy machines are good, but for myself i can weld just fine without the features of the dy machines, and if i can save money and get more amperage with a 250 thats what ill lean towards ( i know right now i cannot use the extra amperage, but the day will come)
    mm210
    maxstar 150

  5. #5
    Join Date
    Aug 2006
    Location
    Browns Valley, California
    Posts
    1,713

    Default

    Power factor correction in welders uses a capacitor bank to balance the inductive load of the transformer. It's a great idea if you have 50 welders running in your business. The issue for one welder in a home shop is that, if the welder is on, the primary side of the transformer will be enrgized, and the capacitor bank will charge and discharge with the line frequency to balance the inductive load of the transformer's primary, even though the secondary is an open circuit. All of this still reperesents a load to the electric meter, which will spin happily away, recoreding the additional energy used to keep the capacitor bank up to snuff, even though you are still doing your fitup!

    This is an oversimplified, and not totally technically correct version, but it says basicaly that a one-machine shop will be hurt more by PF correction that just running straight off the line.

    Run yourself a 60 amp welder circuit and go for it. If you need to weld something that will run that puppy up high enough to pop the breaker, it's prolly to big fer a home shop anyway!

    Hank
    ...from the Gadget Garage
    Millermatic 210 w/3035, BWE
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  6. #6
    Join Date
    Dec 2005
    Location
    Rainier, OR
    Posts
    495

    Default

    Quote Originally Posted by hankj View Post
    Power factor correction in welders uses a capacitor bank to balance the inductive load of the transformer. It's a great idea if you have 50 welders running in your business. The issue for one welder in a home shop is that, if the welder is on, the primary side of the transformer will be enrgized, and the capacitor bank will charge and discharge with the line frequency to balance the inductive load of the transformer's primary, even though the secondary is an open circuit. All of this still reperesents a load to the electric meter, which will spin happily away, recoreding the additional energy used to keep the capacitor bank up to snuff, even though you are still doing your fitup!

    This is an oversimplified, and not totally technically correct version, but it says basicaly that a one-machine shop will be hurt more by PF correction that just running straight off the line.

    Run yourself a 60 amp welder circuit and go for it. If you need to weld something that will run that puppy up high enough to pop the breaker, it's prolly to big fer a home shop anyway!

    Hank
    From a utility standpoint the 'power factor' is a phase shift caused by motor loads on the system. Commerical accounts are monitored for this and
    if the power factor is an issue the account is surcharged because the phase shift disrupts the system all the way back to the generation station.

    the issue is addressed with capacitor banks.

    this is the reason that many utilities have motor load hp limitations on their system without registering your motor. typically non-commercial accounts
    are prohibited from using more than a 5 or 7.5 hp motor on their account
    without special permission from the utility---though I doubt that very many people even know of the limitation or if they do---pay much attention to it.

    but if you fire off a rock crusher or something like that without capacitance to offset the phase shift from the motor load, you will be in the penalty box
    with the utility if they figure out who did it.
    rvannatta
    www.vannattabros.com
    Miller Bobcat 225G
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  7. #7
    Join Date
    Mar 2007
    Posts
    356

    Default

    Quote Originally Posted by hankj View Post
    The issue for one welder in a home shop is that, if the welder is on, the primary side of the transformer will be enrgized, and the capacitor bank will charge and discharge with the line frequency to balance the inductive load of the transformer's primary, even though the secondary is an open circuit. All of this still reperesents a load to the electric meter, which will spin happily away, recoreding the additional energy used to keep the capacitor bank up to snuff, even though you are still doing your fitup!
    that was my big concern, if this sucker is going to be drawing big amperage just sitting, not only costing me money, but cutting into productivity while not welding
    mm210
    maxstar 150

  8. #8
    Join Date
    May 2007
    Posts
    539

    Default

    I would call or email miller support on this question about power consumption at idle. High current draw when not welding just does't sound right to me.

    From the classes way back, and my work with electric motors in the rc world, I have the power meter that plots on my laptop, volts, current / work for dialing in and deciding what prop to use, I can't believe that at idle, (non welding) the machine is going to consume high amps. Pulling numbers out of the air, if idle current is 5 amps, corrected current at idle might be slightly higher. The only time the current draw will increase drasticly is when you are welding.

    On brushed motors we run capacitors to make the motor more efficient, at idle the current is low, at full bore the current is high. Thats the same thing you are talking here.

    If that machine was pulling 40 amps at idle, the inverters would have replaced the transformer machines years ago.

    Please post what you find out from miller.

  9. #9
    Join Date
    Mar 2006
    Location
    Tulsa
    Posts
    117

    Default

    I would see if someone has a amp meter they could put on one while it is idle.
    Millermatic 251, Miller DialarcHF 250 AC/DC Tig/Stick
    Miller Cutmate 375, Victor O/A rig
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    B2 Beverly Shear
    Metabo 7" grinder

  10. #10
    Join Date
    Oct 2004
    Location
    Edmonton, Alberta
    Posts
    7,833

    Default

    There is only a quick inutial surge to charge the caps, there is no actual amp load

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