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Air Compressors

  1. #51
    (4) Try not to be a dick. PurplePackage's Avatar
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    Re: Air Compressors


    it uses 42% less *amps* to turn the same load. converter losses really depend on the converter. 5% loss is a very rough ballpark.

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  2. #52
    Lifer jasnmar's Avatar
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    Re: Air Compressors

    Quote Originally Posted by PurplePackage View Post
    10HP motor is a 10HP motor. It will take 10HP to run it. That is 7.8kW at 100% efficiency.

    Use this calc: https://www.jcalc.net/motor-current-calculator

    10HP motor (240v) on 3-phase draws 22.22 amps with a .85 PF
    10HP motor (240v) on single phase draws 38.48 amps with an equal .85 PF

    You can see how 3-phase is much more efficient at spinning the motor.
    So for the three phase motor, 22.22A * 240V * Sqrt(3) = 9236VA
    For the single phase motor, 38.48A * 240V = 9235VA.

    Efficiency = Power Out / Power In.
    If both motors operate at 7.8kW, with .85PF, that means
    Efficiency Three Phase = 7800W / 9236VA*.85 = .9936, or 99.36%
    Efficiency Single Phase = 7800W / 9235VA*.85 = .9935 or 99.35%

    I wonder if there's some sort of relationship between the current draw of the single phase and 3 phase motor...

    38.48A / 22.22A = 1.732 (aka Sqrt(3)).

    The primary efficiencies to be gained in running motors on 3 phase vs. single phase are mostly in I2R losses.
    There may be savings / costs in breaker size and wiring for the installation as well. For the 3 phase you're running one more conductor, but all of the conductors are smaller.

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  3. #53
    Angry Gumball RandyO's Avatar
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    Re: Air Compressors

    I doubt that I will buy a new 3phase compressor, but maybe a used one

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    RandyO
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  4. #54
    Lifer golden chicken's Avatar
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    Re: Air Compressors

    After approximately 7-8 years owning a 1/4" Milwaukee cordless ratchet and using it every day professionally, today the ball detent fell out of the drive anvil so it no longer retains whatever socket or extension you put on it.

    Luckily, Amazon has me covered and a replacement part is on the way for under $30.

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  5. #55
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    Re: Air Compressors

    Quote Originally Posted by jasnmar View Post
    So for the three phase motor, 22.22A * 240V * Sqrt(3) = 9236VA
    For the single phase motor, 38.48A * 240V = 9235VA.

    Efficiency = Power Out / Power In.
    If both motors operate at 7.8kW, with .85PF, that means
    Efficiency Three Phase = 7800W / 9236VA*.85 = .9936, or 99.36%
    Efficiency Single Phase = 7800W / 9235VA*.85 = .9935 or 99.35%

    I wonder if there's some sort of relationship between the current draw of the single phase and 3 phase motor...

    38.48A / 22.22A = 1.732 (aka Sqrt(3)).

    The primary efficiencies to be gained in running motors on 3 phase vs. single phase are mostly in I2R losses.
    There may be savings / costs in breaker size and wiring for the installation as well. For the 3 phase you're running one more conductor, but all of the conductors are smaller.
    except your numbers are wrong

    three phase would be 208V three phase, single phase would be 120V single phase....

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  6. #56
    Lifer jasnmar's Avatar
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    Re: Air Compressors

    Quote Originally Posted by xrocket21 View Post
    except your numbers are wrong

    three phase would be 208V three phase, single phase would be 120V single phase....
    So there's no such thing as 240V single phase?
    There's no such thing as 208V single phase?

    208V vs 240V depends on whether it's a Y or delta system.

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  7. #57
    Angry Gumball RandyO's Avatar
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    Re: Air Compressors

    Quote Originally Posted by jasnmar View Post
    So there's no such thing as 240V single phase?
    There's no such thing as 208V single phase?

    208V vs 240V depends on whether it's a Y or delta system.
    it is my understanding that in the US, 3phase can come in 120/208/240/277 or 480v depending how it's wired

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  8. #58
    Lifer jasnmar's Avatar
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    Re: Air Compressors

    In the US 120 and 277 can be components of a 3 phase system, but are typically referred to as single phase.
    208, 240, or 480 can be either single phase or 3 phase depending on configuration.

    For a lot of things the term '220' is used, which usually means something that works on either 208 or 240.

    220, 221, whatever it takes.

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  9. #59

    Re: Air Compressors

    Air compressors are now on my list of items that you don’t buy used any more. Ya I know there are some old school amazing models. But there are so many deals on new ones and used ones are overpriced af. Harbor freight and big box stores make it very easy.

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  10. #60
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    Re: Air Compressors

    Quote Originally Posted by tsorfas View Post
    Air compressors are now on my list of items that you don’t buy used any more. Ya I know there are some old school amazing models. But there are so many deals on new ones and used ones are overpriced af. Harbor freight and big box stores make it very easy.
    Until you actually get a big one.

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  11. #61
    Lifer loudbeard's Avatar
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    Re: Air Compressors

    Residential, single phase, 120/240 (also called 220…221, whatever it takes) always has a neutral conductor derived at service entrance.

    Commercial/Industrial, 120/208Y, 277/480Y. 120 is the “house” load, general purpose, requires a neutral. Can also pull 208 single phase which is two of the three supplied phase conductors. These types of circuits induce an unbalanced load over the service, require a neutral bonded at service entrance. If the load is entirety 3 phase then the service is balanced, no neutral required. 277/480Y is the same but with greater potential. Example, lots of commercial high bay lighting is 277V. Think of voltage as electrical pressure.

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  12. #62
    Lifer jasnmar's Avatar
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    Re: Air Compressors

    Quote Originally Posted by loudbeard View Post
    Residential, single phase, 120/240 (also called 220…221, whatever it takes) always has a neutral conductor derived at service entrance.

    Commercial/Industrial, 120/208Y, 277/480Y. 120 is the “house” load, general purpose, requires a neutral. Can also pull 208 single phase which is two of the three supplied phase conductors. These types of circuits induce an unbalanced load over the service, require a neutral bonded at service entrance. If the load is entirety 3 phase then the service is balanced, no neutral required. 277/480Y is the same but with greater potential. Example, lots of commercial high bay lighting is 277V. Think of voltage as electrical pressure.
    There's a small chance that more than 3 people on NESR understand that.
    There's a large chance that less than 6 people on NESR understand that.

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  13. #63
    Lifer loudbeard's Avatar
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    Re: Air Compressors

    Quote Originally Posted by jasnmar View Post
    There's a small chance that more than 3 people on NESR understand that.
    There's a large chance that less than 6 people on NESR understand that.
    Cringed a bit at previous replies, thought maybe I’d clear the air. Turns out I may have farted in a crowded room.

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  14. #64
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    Re: Air Compressors

    Quote Originally Posted by loudbeard View Post
    Cringed a bit at previous replies, thought maybe I’d clear the air. Turns out I may have farted in a crowded room.
    I have no idea what a lot of that meant but electrical is always something that I wanted to learn.

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  15. #65
    Lifer jasnmar's Avatar
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    Re: Air Compressors

    Quote Originally Posted by loudbeard View Post
    Cringed a bit at previous replies, thought maybe I’d clear the air. Turns out I may have farted in a crowded room.
    Lol. No, you're totally right. There's just so much nuance and so little knowledge of electrocity.

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  16. #66
    Lifer loudbeard's Avatar
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    Re: Air Compressors

    Quote Originally Posted by csmutty View Post
    I have no idea what a lot of that meant but electrical is always something that I wanted to learn.
    You need to know none of that for switches, lights, and receptacles. Anything else, call your favorite penguin.

    Quote Originally Posted by jasnmar View Post
    Lol. No, you're totally right. There's just so much nuance and so little knowledge of electrocity.
    I’ll always maintain you can teach a great electrician to be a great mechanic, not so much the other way. Electromechanics with a dash of product management is my career, fantastic way to make a living.

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    I went to MMI I know what Im doing here chief

  17. #67
    (4) Try not to be a dick. PurplePackage's Avatar
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    Re: Air Compressors

    Quote Originally Posted by csmutty View Post
    I have no idea what a lot of that meant but electrical is always something that I wanted to learn.
    just pickup a saw and get cutting down these walls, whatever it takes


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    Last edited by PurplePackage; 09-30-21 at 10:28 PM.

  18. #68
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    Re: Air Compressors

    I've got somethin kinda like one of these but it's the super budget JobSmart brand... it gets the job done fairly well and it's oil, but holy FUCK is it loud!

    https://www.tractorsupply.com/tsc/pr...air-compressor



    I also have one of these for smaller jobs on the go. But mine's red so it goes faster.

    https://www.homedepot.com/p/Husky-4-...4ST2/203287685


    I gotta get myself some air tools to put em to the test. Primarily just use for tires right now.

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    Last edited by OreoGaborio; 10-01-21 at 08:38 AM.
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  19. #69

    Re: Air Compressors

    Quote Originally Posted by OreoGaborio View Post
    I've got somethin kinda like one of these but it's the super budget JobSmart brand... it gets the job done fairly well and it's oil, but holy FUCK is it loud!

    https://www.tractorsupply.com/tsc/pr...air-compressor
    https://www.harborfreight.com/mercha...sor-57336.html

    I was thinking of this one for an upgrade. Under 70dB. Figured I can have find a good spot and make it even quieter for the house.

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  20. #70
    Angry Gumball RandyO's Avatar
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    Re: Air Compressors

    Quote Originally Posted by jasnmar View Post
    There's a small chance that more than 3 people on NESR understand that.
    There's a large chance that less than 6 people on NESR understand that.
    yer right, I don't know how to wire it, but I do know 277v lighting exists, and I understand how the different voltages are arrived at conceptually

    now add 50 cycle into the mix, that other countries have, and confuse us more

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    RandyO
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  21. #71
    Your Father csmutty's Avatar
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    Re: Air Compressors

    Quote Originally Posted by OreoGaborio View Post
    I've got somethin kinda like one of these but it's the super budget JobSmart brand... it gets the job done fairly well and it's oil, but holy FUCK is it loud!

    https://www.tractorsupply.com/tsc/pr...air-compressor



    I also have one of these for smaller jobs on the go. But mine's red so it goes faster.

    https://www.homedepot.com/p/Husky-4-...4ST2/203287685


    I gotta get myself some air tools to put em to the test. Primarily just use for tires right now.
    Air cutoff wheel/die grinder is straight money. Awesome for cutting chains and bolts and such. I think I went with an IR angle grinder and just threw a mandrel and cutoff wheel at it. Most of the stuff they have now is oil free so you don't have to oil it every time you use it.

    Impact is also awesome. I have the hf earthquake and it has been great.

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  22. #72
    (4) Try not to be a dick. PurplePackage's Avatar
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    Re: Air Compressors

    Quote Originally Posted by RandyO View Post
    yer right, I don't know how to wire it, but I do know 277v lighting exists, and I understand how the different voltages are arrived at conceptually

    now add 50 cycle into the mix, that other countries have, and confuse us more
    stare at these graphs long enough and things might make sense, or maybe make things worse

    https://www.thecoffeebrewers.com/electricity.html

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  23. #73
    Angry Gumball RandyO's Avatar
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    Re: Air Compressors

    Quote Originally Posted by PurplePackage View Post
    stare at these graphs long enough and things might make sense, or maybe make things worse

    https://www.thecoffeebrewers.com/electricity.html
    when I was in high school, my older brother built a Tesla coil, awesome, he could light a 4ft fluorescent tube from 10 feet away

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    RandyO
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  24. #74
    Lifer loudbeard's Avatar
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    Re: Air Compressors

    Quote Originally Posted by RandyO View Post
    when I was in high school, my older brother built a Tesla coil, awesome, he could light a 4ft fluorescent tube from 10 feet away
    You made that up, it’s not possible.

    Tesla was only 6 when you were in high school.

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    I went to MMI I know what Im doing here chief

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