Power measurement
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  1. #1
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    Dec 2016
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    Power measurement

    This may sound silly, but i need to do this urgently. i need to measure the power consumed by all the machines in my workshop in kW.

    the machines are lathe, chopsaw, pillar drill, bench grinder, electronic scales, welding transformer and appliances like pedestal fan, ceiling fan, flouroscent bulbs, exhaust fan and a computer with printer

    what kind of device do i need for this job, and what is the methodology ?
    Last edited by ZAVERI; 01-08-2017 at 01:36 PM.

  2. #2
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    Re: Power measurement

    Quote Originally Posted by ZAVERI View Post
    This may sound silly, but i need to do this urgently. i need to measure the power consumed by all the machines in my workshop in kW.

    the machines are lathe, chopsaw, pillar drill, bench grinder, electronic scales, welding transformer and appliances like pedestal fan, ceiling fan, flouroscent bulbs, exhaust fan and a computer with printer

    what kind of device do i need for this job, and what is the methodology ?
    Have a look at your electricity bill, the KWH will be on it, from there you can calculate
    what you use.
    But depending on what you need to know this for then this information may not suffice.
    Are you sizing a generator, a battery bank, transformer, inverter, wiring, more details will help provide the appropriate
    answer.

  3. #3
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    Western New York State, USA
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    Re: Power measurement

    Quote Originally Posted by ZAVERI View Post
    This may sound silly, but i need to do this urgently. i need to measure the power consumed by all the machines in my workshop in kW.

    the machines are lathe, chopsaw, pillar drill, bench grinder, electronic scales, welding transformer and appliances like pedestal fan, ceiling fan, flouroscent bulbs, exhaust fan and a computer with printer

    what kind of device do i need for this job, and what is the methodology ?
    .
    .
    clamp on amp meter
    .
    http://www.harborfreight.com/clamp-o...ter-95683.html
    .
    you clamp over just one wire so normally done at electrical box. it tells you amps
    Volts x Amps = Watts
    240 volts x 20 amps = 4800 watts or 4.8kw

  4. #4
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    Aug 2016
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    Ireland
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    Re: Power measurement

    Reading the OP again, there is no accurate answer, as it will all depend on what tools you use,
    how often they are used, and even on how often they are started as in motors, that use
    considerably more to start and this will reflect on the total.
    Again, if people knew the reason for the calculation it would help.

  5. #5
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    Re: Power measurement

    You need a clamp on ammeter. You multiply Amps times Volts to get Watts.

    Example: your chop saw is lets guess 10 amps times 120volts equalls 1.2KW.

    I use a short extension cord with black and white wires exposed for 120V. You clamp on to either white or black. Clamping to both cancels measurement.

    Another method also useful for 220Volts and probly more practical for your use; open sub/main panel and clamp over black wire at circuit breaker your trying to measure. Also, you could clamp on to one of the incoming panel lines. This will measure all circuits being used at once tho. To get lathe or other tool amps with this method; you could measure and note amps being used before turning on lathe and subtract that amount after lathe is turned on.

    This is what a clamp on meter looks like; you may already have one.

    http://en-us.fluke.com/products/clamp-meters/

    EDIT: I see WnyTom already said clamp on.
    Last edited by Insaneride; 01-08-2017 at 02:35 PM.
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  6. #6
    Join Date
    Dec 2015
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    505

    Re: Power measurement

    You can buy units that go between a device and the wall socket they will measure what it uses, but you are talking a whole workshop, not economical, or possible if you have hard wired gear. Short of putting it on a different meter at your fuse box, if your sharing power with anything else and cant just read it from the meter, best you can do is shut everything else off for a day, read k/watts at start and end of day, but that will be rough, different days you do different things, so daily power consumption will vary quite a bit.

  7. #7
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    Dec 2011
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    Tampa FL
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    944

    Re: Power measurement

    Do you need actual or calculated KW? Take amps from devices data plate time voltage equals watts.


    Mike

  8. #8
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    Oct 2006
    Location
    Illinois
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    8,234

    Re: Power measurement

    Would this GOOGLE thing help ?? http://www.wikihow.com/Calculate-Kilowatt-Hours

    Calculate Electricity Consumption - 4 Easy Steps

    1 . Step. Watts Per Day. To calculate energy consumption costs, simply multiply the unit's wattage by the number of hours you use it to find the number of watt-hours consumed each day. ...

    2 . Step. Convert to Kilowatts. ...

    3. Step. Usage Over a Month Period. ...

    4 . Step. Figuring Out the Cost.

  9. #9
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    Re: Power measurement

    Quote Originally Posted by BD1 View Post
    Would this GOOGLE thing help ?? http://www.wikihow.com/Calculate-Kilowatt-Hours

    Calculate Electricity Consumption - 4 Easy Steps

    1 . Step. Watts Per Day. To calculate energy consumption costs, simply multiply the unit's wattage by the number of hours you use it to find the number of watt-hours consumed each day. ...

    2 . Step. Convert to Kilowatts. ...

    3. Step. Usage Over a Month Period. ...

    4 . Step. Figuring Out the Cost.
    Wont all this already be outlined on ones electric bill for what ever period,
    just divide it by the amount of days worked if a daily average is required.
    No measuring required.

  10. #10
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    Oct 2006
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    Illinois
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    Re: Power measurement

    Quote Originally Posted by Windingroads View Post
    Wont all this already be outlined on ones electric bill for what ever period,
    just divide it by the amount of days worked if a daily average is required.
    No measuring required.
    I would think it would too. He maybe in a ALL electric house with electric heat, water heater, dryer, and stove too. Those really use some serious power.

  11. #11
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    Re: Power measurement

    Quote Originally Posted by BD1 View Post
    I would think it would too. He maybe in a ALL electric house with electric heat, water heater, dryer, and stove too. Those really use some serious power.
    Never thought about that scenario. But did think of looking at the ratings on the electrical plate,
    should be reasonably accurate, then he could factor them in over time used.

  12. #12
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    Nov 2009
    Location
    Arizona
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    Re: Power measurement

    If you have a single phase system you can get Sense: https://sense.com/ For 3 phase get Eyedro: http://eyedro.com/ Eyedro also has single phase units.
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  13. #13
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    Jan 2014
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    First state
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    Re: Power measurement

    Not sure if you need to know on-going actual KW usage, month-to-month, but if that is what you want, then a sub-metering KWH meter is what you need. Here'a an example of one I installed in a building that had a tenant that we needed this:

    http://www.metersusa.com/Watt-Hour-M...att/Meters.htm
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  14. #14
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    Dec 2016
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    Re: Power measurement

    Actually i am planning to get a diesel generator, and hook all the machines to it

  15. #15
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    Re: Power measurement

    Quote Originally Posted by ZAVERI View Post
    Actually i am planning to get a diesel generator, and hook all the machines to it
    thats a good idea, just make sure you hook them real good when you do it

  16. #16
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    Oct 2015
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    PNW
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    Re: Power measurement

    Quote Originally Posted by ZAVERI View Post
    Actually i am planning to get a diesel generator, and hook all the machines to it
    you shouldnt need to do anything more than look on each piece of machinery for a lable that tells you amp draw. calculate from that. you cant run them all at the same time, right? so figure the highest draw at any one time and oversize genny output by 25%. done.

    haha not even close. run your sensitive electronics from a power supply that that has a welder draw from it your going to be looking for trouble unless you have one hell of a genset. to 'urgently' assess your needs and not know how to says to me your going to run into some problems. even a properly sized setup can pose issues. hell i fried a computer on my $12k genset due to the high load unload of plasma cutting. i had to didtch that genny for one better suited for the load swings. but that generator wasn't stable enough to run my computer... get where i'm going with this??? either fork over **** tons of money for a bad *** genny that can do it all or get creative to stay afforable.

    for my application, mobile cnc, i went to a gas powered air supply, dedicated generator for the plas and run computers, lighting, fans etc from battery powered inverters. the batteries charge from the plas gen when the plas isn't in use. pain in the *** to set up but it cost me under $10k for the final setup when a generator to do it all would have been $20-30k. of course i'm talking all bought new if you can find a deal on used then do it! i couldn't afford downtime so evertthing has been bought new for me.

    good luck

  17. #17
    Join Date
    Sep 2013
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    west texas
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    Re: Power measurement

    I have been working on this too.
    First thing you need to do is get an amp clamp or 240v power meter for big stuff and a kill-a-watt meter for the little 120v stuff.
    Then power factor correct everything you can, anything with a transformer or induction motor. Because it's much cheaper and easier to save amps then buy a generator to produce more amps.
    Also run everything that can be hooked up to 240v is ran at 240v, if you have an air compressor that can be wired for 240v operation do it, if you have an inverter welder that can use 120v or 240v power make a 240v plug for it and use 240v power.
    Then all you need to know is how much everything uses and how much you will run at the same time.
    Also power factor corrected big equipment will allow the sensitive stuff to run better when used at the same time.
    Last edited by mad welder 4; 01-09-2017 at 10:59 AM.
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  18. #18
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    Re: Power measurement

    Quote Originally Posted by mad welder 4 View Post
    I have been working on this too.
    First thing you need to do is get an amp clamp or 240v power meter for big stuff and a kill-a-watt meter for the little 120v stuff.
    Then power factor correct everything you can, anything with a transformer or induction motor. Because it's much cheaper and easier to save amps then buy a generator to produce more amps.
    Also run everything that can be hooked up to 240v is ran at 240v, if you have an air compressor that can be wired for 240v operation do it, if you have an inverter welder that can use 120v or 240v power make a 240v plug for it and use 240v power.
    Then all you need to know is how much everything uses and how much you will run at the same time.
    Also power factor corrected big equipment will allow the sensitive stuff to run better when used at the same time.
    120v or 240v doesn't matter: the generator will only provide X amount of watts. Running machines on 240v does NOT change the wattage consumption- only the amperage on the wires.


    3000 watt machine on 240v= 12.5 amps
    3000 watt machine on 120v = 25 amps

    watts don't change.
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  19. #19
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    Sep 2013
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    Re: Power measurement

    I know that.
    Running everything that can use 240 being ran on 240v power eliminates the problem of loading up one 120v side or the other.
    Also using 240v there will be less voltage drop.
    old Miller spectrum 625
    Lincoln SP-135 T, CO2+0.025 wire
    Craftsman 230amp AC/DC and WP-18V torch
    Craftsman 100amp AC/DC and WP-17V torch
    Century 115-004 HF arc stabilizer
    Home made 4 transformer spot welder
    Home made alternator welder

  20. #20
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    Dec 2007
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    Los Angeles
    Posts
    7,015

    Re: Power measurement

    Quote Originally Posted by ZAVERI View Post
    Actually i am planning to get a diesel generator, and hook all the machines to it
    is this back up power for your shop? Or do you just not have enough power feeding the shop and can't get more from the Power company?


    Where are you located?
    Ed Conley
    http://www.screamingbroccoli.com/
    MM252
    MM211 (Sold)
    Passport Plus & Spool gun
    Lincoln SP135 Plus- (Gone to a good home)
    Miller 125c Plasma 120v
    SO 2020 bender
    Beer in the fridge

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