in power system in transmission line how 3 phases is transformed into 1 phase??

Question

inour home 1 phase power supply is given,but inour locality we alsop see the 3 phase line.of what purpose??

Answer 1

For low power applications 1 phase will be sufficient. So take one of the three phases and neutral so that you get 1 phase.

For high power applications 1 phase will draw heavy current and so 3 phase is used.

The power is generated as 3 phase and so is supplied to us for use.

Answer 2

Usually, generators produce 3-phase electricity. But it is also advantageous to transmit 3 phases over longer distance power lines, because that requires less copper (thinner cables) than transmitting the same power over only one wire. Not sure whether you are familiar with Ohm's law, but the more current you send over one wire (which is, in essence, a resistor), the more power you lose along that wire. So you spread the current over 3 wires......
A transformer (somewhere nearer where you live) transforms then the high voltage 3-phase power into (usually) two distinct phases of 110 Volt each. Some houses (with 220 Volt appliances) have 2 of those phases, others only have one.

Answer 3

In a 3 phase system any combinatin of two lines will provide a single phase.

1 + 2
2 + 3
3 + 1

would each make up the three distinct phases.

Answer 4

transmission lines are three phase only. distribution lines( lines used for suppling or distributing supply to houses) are three phase four wire system.for industry all for running motors three phase is requried.but for house application only single phase is required for that one phase and neutral wire is used.