[rahul_chaubey]

Can any body tellme what is difference between 2-PHASE and 3-PHAE connection of electricity

[ebaines]

Quick tutorial:

2-phase electrical circuits have 2 wires, where the voltage on the wires is 180 degrees out of phase with each other. The 220-volt service to a house is this type. Each wire carries 110 volt A/C (relative to earth), and because they are 180 degrees out of phase with each other the voltage reative to each other is twice 110, or 220 volt.

3 phase uses 3 wires, where the voltage on any one wire is +/- 120 degrees out of phase with the other two. This is typically used in the distribution network by the power companies and commercial/industrial electrical wiring. Ever notice that high-voltage transmission lines always have increnments of 3 wires on the tower? That's because each wire carries one of 3 phases of the voltage.

[tkrussell]

Sorry to correct ebaines, but a household service is still a single phase, not a two phase. It sometimes is called a split phase, since the neutral is a center tap on a single phase transformer.

To learn of the rare, now almost obsolete, two phase system see:2 Phase Power Systems and Two-Phase Electric Solutions

[Stratmando]

In addition to tkrussel's post.
Single Phase used mostly residential and three phase for commercial or industrial for
Efficiency of motors and compressors.
If interested: revesing 2 wires on single phase motor will not change direction, (has to be done with motor tap wires)That would
Be DC motor that reverses by changing polarity.
Three phase motor can be reversed by switching any two of three wires.