1. If you have 3 single phase RTU's , each drawing 30 amps and balanced them on a three phase service they would draw 60 amps per phase. The same 3RTU's in three phase would only draw 20 amps. After hooking these up it would draw 60 amp per phase. It is the same.

2. Originally Posted by beenthere
There are other far better explanations of 3 phase then the one you found.

That one is a little misleading.

1/3 the power doesn't "just" bounce between the winding.

But, the OP's question, was a system question, not a componet question.

boing, boing, boing. Yeah 3 phase is more efficient because 1/3 of the energy is just "bouncing" around in the windings. That makes it sound real efficient doesn't it.

3 phase works better because when you look at the sine waves of all three phases you always have a phase that is carrying current on the positive side of the wave. This makes for a stronger motor. However you still are using power. A 1 hp motor is still rated at 746 watts regardless if it has single phase, three phase, or dc power feeding it. 150% more efficient means that is using it's energy in a better manner, meaning more torque, less heat, which allows for a smaller motor package.

Now this means that if you use a 3 phase motor instead of a single phase motor you "May" be able to reduce the required HP to perform the same amount of work. This however is not what we are talking about here.

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