What's the basic difference between 480 three phase and 480 single phase?

Question

What's the basic difference between 480 three phase and 480 single phase?

Answer 1

2 phases?

Answer 2

I suppose if you really wanted the Wikipedia answer, you would have looked that one up yourself . . .

480V 3 phase is three "hot" wires (phases), each 120 degrees out of phase referenced to the other two, and a neutral.  Neutral and safety ground should be at or near the same potential.  Measuring with a voltmeter between any phase to neutral or ground will give you 277V RMS, and between any two phases you will get 480V RMS.

Single phase indicates that you are connecting your device between two of the "hot" wires as opposed to a three phase device that requires all three.  Connecting between one phase and ground is considered 277V service.

I know the next obvious question is, if they use two phases, why is it called single phase?  I don't know, they just do.

I hope this helps.

Answer 3

If you would like to see a diagram of the power curves of single phase vs 3 phase, you can look here

http://users.ticnet.com/mikefirth/electr...

Three phase is how power is generated at the plant providing a smoother mechanical load than one phase and delivering more power per second than one phase to places that need lots of power.

Answer 4

There are three phases in most high voltage networks - large motors are also typically wired for three phases down to 480VAC applications - it provides for a more efficient motor, and will only rotate one direction - depending on how it is wired.  (swapping any two phases will change the direction of rotation, although typical motor installations are designed for one direction - i.e. pumps)...

Single phase installations are typically very low voltage (220 or 120VAC, and fairly low power.  Household equipment is typically single phase, however there are three phases in most modern residential systems, just split so the household appliances use single phase power.  (as an example, I have a 220VAC well pump that is three phase - less current per phase for a given power output...)

Answer 5

480 VAC is produced as a 3 phase power source. Widely used here in the USA for industrial applications.

This voltage is not typically considered single phase, it is Line - Line. The 480VAC is transformed into 120VAC/220VAC for typical control circuits after it enters a control cabinet. The control Xfmr uses 480VAC line-line on its input.

This voltage to earth ground is not 480VAC, it is 480V/sqrt(3) = 277VAC.

Check out the 3 Phase power distribution below: