# What is Three Phase Supply?

• ranju
This makes three phase more efficient. In summary, three phase supply is a type of power transmission where there are three phases of voltages supplied, 120 degrees apart from each other, which is more efficient than using three independent single phase transmission systems.

#### ranju

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..!

ranju said:
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.

ranju said:
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.

ranju said:
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.