stillirnin

Having hard time putting an every day situation in to some example that I can better understand..... lets say you have a motor,equipment 240 3ph 20 amp than lets say same motor,equip but 480 3ph, now its only 10 amp what is it about the higher voltage that motors.equip. etc use less amps . I understand ohms law ampacity of conducters emf, just cant paint a picture in my mind of what happens in the use of higher volts

TOMWELDS

2X's the voltage =1/2 the amperage

stillirnin

I GET THAT ,I GEUSS IM TRYING TO LOOK A LITTLE DEEPER INTO IT,LIKE WHAT PROPERTIES DO THE HIGHER VOLTAGES HAVE THAT ALLOW THEM TO CUT THE AMPS. i CAN GO ALL DAY LONG FIGUREING WITH THE FACE VALUE OF THE WHOLE THING AND FIGURE CUNDUCTER SIZING ETC BUT REALLY WOULD LIKE TO HAVE A MORE IN DEPTH UNDERSTANDING... THANX FOR YOUR REPLY TOMWELDS

te12co2w

Would it help to think of terms of pressure? If you equate voltage with pressure then the more static pressure you applied to something, then maybe it would take less force to accomplish a given task. If you apply 120 pounds of pressure to a stuck door to open it then it might take 20 more units of "force" to open it. If however, you apply 240 pounds of pressure to the same stuck door it might take only 10 more pounds of "force" to accomplish the same thing.
You could also think in terms of water pressure. 120 pounds of pressure could force a given amount of water through a given size of hole. Whereas 240 pounds of pressure could force twice the amount of water through the same hole.
I hope the scientists out there don't jump on me and tell me I'm all wet. Just trying to illuminate the issue.

220/221

Can you picture what would happen washing you car with twice the water pressure?

Voltage = pressure

Amperage = flow

stillirnin

Hmmm.... so 120 vac 20 amp lets say garden hose 60 psi 10 gpm 240v 10a pessure wash 1000 psi 5gpm more butt less pay out ......

micromind

Think of it like this; the shaft output of a motor is based on watts. Forget about power factor and all that sort of stuff. In this case it remains constant. If the watts stays the same, and you raise the voltage, then according to ohms law, the amps will be reduced.

stillirnin

yep I get it when doing the math part of it....... maybe what Im sort of looking for is the scientific end of it ,is there somethig with its structure or the effect on atoms structure that allows it to use less. and is ther any other gain than efficency, lower cost, smaller conducters etc. 5hp 230/3 15.2 a 5hp 460/3 7.6a does the 460 deliver any thing other than efficency to the 5hp

goose134

With motors it may have something to do with generation of magnetic field. The higher the voltage, the stronger the field. And yes, amperage plays into field strength too. But because most motors are inductive, field driven applications, this may have something to do with the amount of "effort" it takes to spin it. I may be wrong. But probably not completely.

waco

I've thought about it and I guess I don't remember the physics. But, I think the reason higher voltage can do the same work with lower current is because electrons are raised to higher energy levels (at the electron level) so energy is exchanged more rapidly and energy is always measured over time.

That said, in a purely resistive circuit (no reactance,) higher voltage does not result in lower current. However, higher voltage will produce the same work with less current for a given resistance, but that work is heat.

Sure has been a long time since I thought about theory!