VFD

I would do the 220 wherever possible. Even though it is the same total watts, spreading it across 2 legs is easier on equipment.

Dave

Here I am again. The great naysayer.

Equipment is not cheaper to operate at a higher voltage. Period. Volts times amps equals watts. Guess what you pay for? Thats right kilowatts. 746 watts make a horsepower. Run a one horse motor for an hour and you get charged for about 1 kw of power usage.

Dave is right I don't know where rdhem2 lives but you balance the load on two legs it draws less power which equals less Kilawatts the meter doesn't care it counts one leg or both.

Todd
 
Mr. Walltoddj:

W = V x A Watts equal volts times amps.
W = P Watts = Power
P = E x I, Power equals Voltage times Amperage
P = R x I[SUP]2 [/SUP]Power equals Resistance times Amperage [SUP](Squared).[/SUP] P = E[SUP]2[/SUP] / R Power equals Voltage [SUP](Squared)[/SUP] divided by the Resistance.

What am I missing here? Anyone?

240v times 6 amps equals 1440 watts of power consumed.

120v times 12 amps equals 1440 watts of power consumed.

240v is 2 times 120v.

6 amps is one half 12 amps.

BOTH are the same end result when measured in power consumed.

Please show me differently. By math. By formula. Anyway you choose that is an accepted manner. A quote from an instructor. From an engineering handbook. I am ready to learn what my instructors left out. Always hungry for something new to learn.

Thank you, awaiting your reply in my world.
 
Ray is right in what he has said but if you are adding machines or have more machines 220v is cheaper to run. With all of my tools I try to run 220v be it 1ph or 3ph and in my most active times in the shop running the lathe 5hp, my welders, and other tools it cost me about $20 a month which I don't think is to bad.


Todd

Large motors are more efficient at 220 and therefor slightly cheaper to run. At 1/2 hp the difference is negligible and offset by the inconvenience of needing a 220 circuit. At 5hp it's definitely worthwhile.
 
You guys are both right -but looking at it in different ways.

If you pull 1 kWh from the electrical panel, it makes no difference if it's 110, 220 or single phase or 3 phase... The power company charges you for 1kWh. Plain and simple.

With 3 phase equipment and 220 single phase, the current draw on the conductors is reduced. When conductors carry current, there are small power losses in the wiring that is proportional to the square of the measured current. If you reduce current by 1/2 or 1/3 in each conductor, you decrease power losses in the conductors dramatically more. If you use properly sized wiring, the losses in the first place are negligible. What this means, is that with 220 single phase or 3 phase equipment, more of the power you're paying for goes into producing work and less is lost in heat in the circuit providing the power. Again, with properly sized wiring, the heat losses in the wiring is negligible.

Next: Because of the mechanics of a 3 phase motor, they are inherently more efficient by a few percent. 3 little pushes on the rotor is more efficient than one big one. A few percent is not a lot. BTW: Mechanically, there is no advantage in single phase 110 vs 220 -both spin the rotor with one big push every rotation. 3 Phase pushes 3 times with every complete rotation and it is a mechanically superior design.

Also, single phase motors (110 or 220) need start and possibly run capacitors. There are small losses in the current flowing through a run capacitor -but not much. The start capacitor causes the motor to fight itself at startup and this causes a brief momentary period of high inefficiency at startup only. 3 phase motors do not need start capacitors or start windings.

As soon as you power a 3 phase motor with a VFD, all the inherent efficiencies get eaten-up by the VFD conversion process and circuitry. It's a wash.

Forget a minute about motors and think about a heating coil.

If the heating coil is putting out say 10kW and if the conductor wires supplying power are properly sized, it makes no difference if it's 110, 220 or single or 3 phase. It will cost exactly the same out of your wallet. If the wires are not properly sized, it will cost more to run the single phase than for the 3 phase.


Ray
 
Ray C writes: Next: Because of the mechanics of a 3 phase motor, they are inherently more efficient by a few percent. 3 little pushes on the rotor is more efficient than one big one. A few percent is not a lot. BTW: Mechanically, there is no advantage in single phase 110 vs 220 -both spin the rotor with one big push every rotation. 3 Phase pushes 3 times with every complete rotation and it is a mechanically superior design.

It's not three pushes. It's steady continuous torque. The three-phase stator generates a steady rotating field. This is a significant difference because it means that there is no inherent vibration.
 
It's not three pushes. It's steady continuous torque. The three-phase stator generates a steady rotating field. This is a significant difference because it means that there is no inherent vibration.

There are special purpose motors that are poly-phase beyond 3... They exist because it provides an even more steady torque with an even steadier rotating field... Are they rare? Yes -but they exist for a reason -which is just an extension of the superiority of 3 phase over single phase. They pulse less.

Ray
 
Ray C

I know the cost of op is the same. My real qustion is, I have eather power avilible The package I am looking at is the same price for eather 110 or 220 input. So would the VFD be happyer with 220 mabe run cooler or is it all the same.
 
Ray C

I know the cost of op is the same. My real qustion is, I have eather power avilible The package I am looking at is the same price for eather 110 or 220 input. So would the VFD be happyer with 220 mabe run cooler or is it all the same.

If it's not a trouble for you to wire a 22 line, I'd go with the 220 just for the sake of future versatility and to capture the very small gain we've discussed about 220 vs 110. From the perspective of the VFD, given the 1/2 to 3/4 HP you're powering, it's about the same.


Ray
 
thanks

220 is already there so I will go that rout. Thanks for all your help.
 
Mr. Walltoddj:

W = V x A Watts equal volts times amps.
W = P Watts = Power
P = E x I, Power equals Voltage times Amperage
P = R x I[SUP]2 [/SUP]Power equals Resistance times Amperage [SUP](Squared).[/SUP] P = E[SUP]2[/SUP] / R Power equals Voltage [SUP](Squared)[/SUP] divided by the Resistance.

What am I missing here? Anyone?

240v times 6 amps equals 1440 watts of power consumed.

120v times 12 amps equals 1440 watts of power consumed.

240v is 2 times 120v.

6 amps is one half 12 amps.

BOTH are the same end result when measured in power consumed.

Please show me differently. By math. By formula. Anyway you choose that is an accepted manner. A quote from an instructor. From an engineering handbook. I am ready to learn what my instructors left out. Always hungry for something new to learn.

Thank you, awaiting your reply in my world.

I'll try one more time and then I done! Yes the do have the same wattage but the whole point that you are missing is on 110v you have 1440 watts on one leg the meter reads the most draw, but with 220v you have two legs 720 watts on each leg so the meter only reads 720 watts not 1440 this is why you see most equipment wired for 220v. As to the smaller motors it make no difference it does if you are running a lot of machines by running 220v you balance the load, I've got probably 15 machines in my shops at this point i need to convert 4 to 220v. Now if you are running 220v your load is balanced if your running 110v you need to look at what runs the most and by moving the breakers you can balance the load and yes it will reduce your electric bill. My shop cost me about $20 a month to run in the summer which is when I'm in it the most. By paying attention to what is doing what I've reduced my electric bill by $50 this month and it was colder this year than it was last year. It's the little things that add up and every small motors add up over time if you use them on a regular basis.
Just to be should I talked to my son who is a Journeyman Electrician and that is what he told me as well.

Todd:whiteflag:
PS. I'm only trying to help none of us can afford to waste money an every penny counts in retirement!!
 
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