# Three phase supply

we talk about three phase supply .. I want to know that what actually is three phase..?? Its obvious there are three wires carrying current but what is "phase" ?
Is there something like, transmission line is further divided into three wires ..?? Please explain..its quite basic.. and I am confused..!!

## Answers and Replies

phinds
Gold Member
2021 Award
we talk about three phase supply .. I want to know that what actually is three phase..?? Its obvious there are three wires carrying current but what is "phase" ?
Is there something like, transmission line is further divided into three wires ..?? Please explain..its quite basic.. and I am confused..!!
You are right that it is quite basic and a simple Google search should turn up a good explanation with diagrams. Basically, it means exactly what it says ... there are three phases of voltages supplied, 120 degrees from each other.

we talk about three phase supply .. I want to know that what actually is three phase..?? Its obvious there are three wires carrying current but what is "phase" ?
Is there something like, transmission line is further divided into three wires ..?? Please explain..its quite basic.. and I am confused..!!
the article above should help.

we talk about three phase supply .. I want to know that what actually is three phase..?? Its obvious there are three wires carrying current but what is "phase" ?
Is there something like, transmission line is further divided into three wires ..?? Please explain..its quite basic.. and I am confused..!!

The phase means the angular difference between the sinusoidal voltage on one wire to another. For three phase, the angular difference would be 360/3 = 120 deg. Instead of having three independent single phase transmission system which require (phase + neutral wire for each phase) 2*3 = 6 wires, if we go for three phase system with angular displacement of 120 deg we need only (1 wire for each phase and 1 common neutral) 3+1 = 4 wires for the same power transmission.