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  1. #1
    Join Date
    Feb 2007
    Location
    Florida
    Posts
    202

    Hmm Hey Electrical Engineers 460v vs 230v 3 Phase

    Can anyone settle an argument for me.

    Whats cheaper to run? "Without" regards to startup amps. Just nominal run time.

    Just for example...

    25 hp compressor
    45 amps at 230v 3ph
    OR
    22.5 amps at 460v 3ph

    My beef is, they consume the same power! but its a ongoing argument and no one really knows?

  2. #2
    Join Date
    Jan 2010
    Posts
    6,056
    Quote Originally Posted by 94blowncobra View Post
    Can anyone settle an argument for me.

    Whats cheaper to run? "Without" regards to startup amps. Just nominal run time.

    Just for example...

    25 hp compressor
    45 amps at 230v 3ph
    OR
    22.5 amps at 460v 3ph

    My beef is, they consume the same power! but its a ongoing argument and no one really knows?
    My vote is it's a wash. Unless the electric co. gives a better rate for the higher voltage.

  3. #3
    Join Date
    Apr 2010
    Location
    Ontario
    Posts
    474
    460 volt consumes less current, less cost to operate.
    ENJOY THE RIDE

  4. #4
    Join Date
    Feb 2007
    Location
    Florida
    Posts
    202
    Quote Originally Posted by Peztoy View Post
    460 volt consumes less current, less cost to operate.
    Well........

    Thats the argument. Mathmatically they equal the same wattage...right?

  5. #5
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,886
    But using Ohm's law, wouldn't the wattage be the same and that's what you are paying for?

  6. #6
    Join Date
    Jan 2011
    Location
    Louisville, KY
    Posts
    20
    What is the line voltage supplying the transformer? The difference will be the the losses in transforming the incoming to the correct voltage into the unit. In our plant we have 13.8 with large efficient transformer that goes to 480. step down again and you have more losses therefor in our plant 480 is less cost to operate.

  7. #7
    Join Date
    Jan 2010
    Posts
    6,056
    Quote Originally Posted by drjfjr View Post
    What is the line voltage supplying the transformer? The difference will be the the losses in transforming the incoming to the correct voltage into the unit. In our plant we have 13.8 with large efficient transformer that goes to 480. step down again and you have more losses therefor in our plant 480 is less cost to operate.
    What if the service is 480 or 240 and no step downs ?

  8. #8
    Join Date
    Jan 2011
    Location
    Louisville, KY
    Posts
    20
    kw=kw if no losses in transmission then no difference in efficiency

  9. #9
    Join Date
    Mar 2003
    Posts
    7,321
    thats a small motor, but for larger motors, look at the difference in cost for conductors, conduit, and installation. on larger loads, it can be a lot.

  10. #10
    Join Date
    May 2010
    Posts
    1,291
    Higher the voltage the lower the amps. Let's say we have a motor running at 110v and 8 amps. If you run 220v to that same motor the amps will be cut in half (4amps). Your electric bill is in kW. Therefore, you would see no cost difference between the two voltages. 220v requires 1/2 the time to do what a 110v circuit does.

    watts=volts(amps)

    Now, the difference in cost of wiring and components... 220v will cost more as you need two 110v legs. So 220v circuits will costs 2x (or more depending on gauge) as much to install compared to a 110v circuit.

    Say you had a 110v hot tub and a 220v hot tub. The 220v hot tub will heat up 2x faster than the 110v but use the same amount of energy. As for motors it won't matter as the RPM's will remain the same.

    As everyone is stating if their is losses in transmission then you will see a fraction of savings but nothing worth noting
    Last edited by ZeroTolerance; 03-02-2011 at 10:50 PM.

  11. #11
    Join Date
    Sep 2005
    Location
    Atlanta GA area
    Posts
    20,856
    If I remember... in the OP's question; we were comparing 460 3ph to 230 3ph...

    IMO the KWH will be the same, so the cost to operate theoretically will be the same. Some power co's may offer different rates for different services... talk to the power co.

    The difference is the circuit to the unit... If the 230V unit uses 45A, then it needs 6 GA wire... If the 460V unit uses 22.5A then it needs 10GA wire... And we both know the cost difference on those two cables. Lets not forget larger conduit, larger disconnect, and larger breaker.

    The major advantage to higher voltage is less expense in the supply circuit. Not much on one unit... but on the roof of a Walmart, and you may save a significant amount to Sparky.
    GA-HVAC-Tech

    Quality work at a fair price with excellent customer service!

    Romans Ch's 5-6-7-8

    2 Chronicles 7:14

  12. #12
    Join Date
    May 2010
    Posts
    1,291
    Yes, we were.... I was just comparing apples with apples as the difference in 110 and 220 is the same as 230 and 460.

    Would you like me to change the voltage values in my post to appease you?

    Also, gauge size is determined by length of run btw. So, your post above is somewhat inaccurate

  13. #13
    Join Date
    Sep 2005
    Location
    Atlanta GA area
    Posts
    20,856
    Quote Originally Posted by ZeroTolerance View Post
    Yes, we were.... I was just comparing apples with apples as the difference in 110 and 220 is the same as 230 and 460.

    Would you like me to change the voltage values in my post to appease you?

    Also, gauge size is determined by length of run btw. So, your post above is somewhat inaccurate
    Hmmm,

    Somehow I do not remember quoting anyone in my post... sorry if it sounded personal... it was not meant to be.

    The point was to compare 3Ph to 3ph at different voltages.

    As to the wire size... both examples have lots of room (length) in them...

    However just for the record: Tell me the max ft of 10GA wire on 22.5A and the max ft of 6GA wire on 45A... that way we both can be right...
    GA-HVAC-Tech

    Quality work at a fair price with excellent customer service!

    Romans Ch's 5-6-7-8

    2 Chronicles 7:14

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