Power Factor correction

Discussion in 'The Projects Forum' started by hhhunzai, Dec 12, 2011.

  1. hhhunzai

    Thread Starter Member

    Nov 14, 2011
    72
    0
    Hello Polychromeuganda,
    I have a power factor corrector of duccati is installed, I want to install an other PF correction relay.
    Would you please tell me how I can calculate the Power factor of of an installation.
    The Installation is a critical problem, that is there are a number of pumps with 55KW motors, which do not continuously running but at different timings there are.
    What should be the criteria of designing PF correction for this kind of Installation?

    Thank you, awaiting for your reply.

    HHH
     
  2. polychromeuganda

    New Member

    Dec 12, 2011
    8
    0
    To get PF you measure load current and load voltage using instrumentation that seperates real and reactive part. You can buy or rent the equipment, you probably only need it for a few days to begin your design, and then after you build it to check the result.

    Your local power company has system engineers who do this for their system from time to time. Ask for a short meeting (1/2 hour) to explain just a little of your project and ask them to suggest equipment that you can get and where. Don't try to do this on the phone. Ask to meet in person at their office. You get better answers in person, and they might follow up by coming to your plant and get all the data you need much more quickly than you could.

    Correcting your PF to 0.8 is a typical goal, but your local power company may have specific guidance. For example if you are far away from the generator and from other loads, you may be paying real money for transmission losses on every VAR, and correcting to 1.0 PF would be cost effective. If they are 1/2 mile away, and moderately loaded they may be able to make your vars less expensively than you can. It is also possible that you are adjacent to a large data center with an uncorrected leading power factor and the power company is counting on you and the data center to cancel each other out. (If you are generating your own power, you should consult with the generator manufacturer)

    As to the design of the capacitor bank - 1 big bank is only simpler until it fails. Multiple smaller banks will fail more often, with smaller consequences. Controlled by computer is nice until it fails, or someone uploads a software update that crashes both the primary and backup controllers. A manually operated board is a good backup plan if software can undo n+1 redundancy.

    Whatever solution you pursue should make economic sense (cost less) in a reasonable time. If it can pay for itself in 1 year, its a good plan. if it will take 100 years to pay for itself - its a bad plan. In between, management usually holds meetings about it until you come up with a design that pays for itself in 1 year.
     
  3. hhhunzai

    Thread Starter Member

    Nov 14, 2011
    72
    0
    You r very true sir and your advices are too good to think about and I have done some point here u described, but please tell me how may I find KVAr without having a KVAr calculating & recording machine, Is there any way that would be available with a digital multimeter with which we can calculate current and voltage.

    HHH
     
  4. Georacer

    Moderator

    Nov 25, 2009
    5,142
    1,266
    Your post, originally found here (http://forum.allaboutcircuits.com/showthread.php?p=430976#post430976), has been moved into its own thread, where it will draw more responses.

    Please refrain from "hijacking" existing threads with tangent or off-topic questions. You can create new threads for new questions using the "New Thread" button on the upper left of the page.
     
  5. hhhunzai

    Thread Starter Member

    Nov 14, 2011
    72
    0
    Ok I am sorry for that, I didn't know about it yet.
    Please tell me about the topic, what are your Ideas about it.
    Thank u.
    HHH
     
  6. hhhunzai

    Thread Starter Member

    Nov 14, 2011
    72
    0
    Any One please comment on this topic, Do you have any idea about it please.?
     
  7. hhhunzai

    Thread Starter Member

    Nov 14, 2011
    72
    0
    If any one have Idea about this topic please?
     
  8. DickCappels

    Moderator

    Aug 21, 2008
    2,648
    632
    What I think you are thinking of is the "Three voltmeter method", which is a little bit complicated but allows you to calculate the phase difference in reactive circuits.

    The method is described on page 6 of this powerpoint presentation:
    journal.mercubuana.ac.id/data/pertemaun%2013.ppt
     
  9. hhhunzai

    Thread Starter Member

    Nov 14, 2011
    72
    0
    I have checked it and know a little about it.
    I am searching a new idea, to measure through easy calculations.
    If you can understand me , please let me know through calculations.
     
  10. DickCappels

    Moderator

    Aug 21, 2008
    2,648
    632
    If I knew an easier way, I would have told you about it. If you find an easier way, please share it with us.
     
  11. hhhunzai

    Thread Starter Member

    Nov 14, 2011
    72
    0
    Yes Ofcourse why not.
    I am searching and when ever I will get one I will share it.
     
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