Power Factor Correction in a residence

Discussion in 'The Projects Forum' started by Daven540i, Feb 22, 2016.

  1. Daven540i

    Thread Starter New Member

    Feb 21, 2016
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    Hello and thank you for taking the time to read and respond to my post.

    First of all you should know that I do not know squat about electrical theory which is also what brings my here. I have read over the years that spikes in electrical current draw cause one to be overcharged for electricity. I have read about devices that you connect up to an electrical panel can save on your power bill. I made an assumption that these devices just contained arrays of large capacitors to compensate for the startup of appliances with electric motors. So I did some searching on eBay and found a new in the box capacitor array for a 3 phase APC power supply. I figured this would do the trick. The capacitor array has 5 large capacitors in series connected to a lug. Each capacitor reads "70uf 370v 50/60hz 50c".

    Although my house is not 3 phase I figured I could either not use the third bank or split them up on the other 2 phases. I purchased an 18x18x8 pull box to house the unit and my thought was to connect up the array to my electrical panel with #8 wire and land it to a double pole 30 amp breaker. My electrical panel would be no more than 5 feet away from the capacitors. So after doing all this (nothing hooked up to panel thus far) I have done some more reading on the subject which led me to this forum. I have read on this forum that the expense for residential power correction does not justify the cost. I have already spent the money which was minimal so I would like to move forward on my project. I have read about all the complex calculations required to determine capacitor size (complex to me). What I am wondering is if I am completely wasting my time (consider it would take me under an hour to connect to my panel and make any adjustments to the capacitor array as to the number of capacitors were on each leg). Could I hurt anything by doing so?

    If I use to many capacitors or too little is that a problem? Could an educated guess be made on the capacitance needed? If this helps I have a 200AMP service 240 volts in the U.S. I have two refrigerators, one has to condensors, one for the refer the other for the freezer. I have to 4 ton air conditioners and a 5 h.p. Compressor which is used almost daily. Many of the lights in my home are Low voltage so they contain a coil in ranch to step down the voltage to 12v from 120. If I need more info please ask. Thanks for your help
     
  2. #12

    Expert

    Nov 30, 2010
    16,257
    6,757
    Residential power meters do not charge for poor power factor correction in the U.S.A.
    They already measure the actual power instead of the apparent power.
    You can adjust capacitance all day and the meter won't know or care.

    If that was false, you would be working on a perfectly valid method to correct for inductive loads. I tried it. My refrigerator needed 80 uf in order to achieve its lowest current draw. That was 3 amps instead of 5 amps. It looks like a 40% improvement, but the meter doesn't know that. It is already designed to ignore the phase angle of the power. Your capacitors might diminish some of the noise caused by lightning or switching transients, but I settled on using a "whole house" surge protector. Around here, the electric company will install one and rent it to you, but I bought one at Home Depot for $35. That is less than the cost of renting one from the power company for one year. They do degrade over time, so I replace it every ten years whether it needs replacing or not.
     
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  3. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,772
    931
    If you ever plan to run your electric appliances in an off-grid fashion, the power factor correction you are doing will be a benefit to efficiency for your power generator.
     
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  4. Daven540i

    Thread Starter New Member

    Feb 21, 2016
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    So if I install the capacitors since I already have them will it hurt anything? A/V equipment? Condensors? Will it improve the quality of my power?
     
  5. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    installing the caps is ok, but to really do power factor correction, you have to have a dynamic corrrector,. he inductive oas on the refrigerator starting is different than running. same with airconditioner, starrt and run power factor are different. also the load on the compressors in the ac and refrig changes as they run.the power comapies power factor corredtion is done with a big bank of caps, with scr's switching them in and out to correct the phase.
     
  6. Daven540i

    Thread Starter New Member

    Feb 21, 2016
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    0
    Let me try asking my question in a different manor as I seem to not be getting the answer I'm looking for. Please don't take this as a negative, I am merely trying to understand something I don't understand.

    If I had a wheel bearing that was packed with grease a year ago and only needs to be packed every 5 years but I go ahead and repack it now I benefit from not needing to repack the bearing for another 5 years. I know I'm not hurting anything and I may have a benefit from it.

    Perhaps a lousy analogy but. . . .

    I install my bank of capacitors. Can to many hurt? Is it helping? Why? Better electrical quality? Should I just say screw it and put the capacitors back on eBay? If there is any benefit to installing them it would literally take me about 30 minutes to hook it up.
     
  7. #12

    Expert

    Nov 30, 2010
    16,257
    6,757
    The capacitors won't hurt anything if they are attached right after the meter. They are merely a waste of time and money unless you want to help the local energy corporation with their phase angle correction. Consider the idea that the capacitors continue to pass current when nothing is turned on. That is the opposite of the alleged goal. If you place the capacitors after a switch which turns a motor on, they will cause current spikes that might weld the switch in the, "on" condition.

    The, "whole house" surge protector will absorb voltage spikes better than the capacitors will, and probably cost less. The surge protector has no idle current. It only works when you need it.
     
  8. Daven540i

    Thread Starter New Member

    Feb 21, 2016
    4
    0
    I have a surge suppressor from AC Data Systems model AC2100-F-NA. I had planned on attaching it to the lugs of the capacitor array. I guess I will forego the capacitors and just install the suppressor
     
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