Types of Alternating Current Direct Current transmission

The transmission in the Power System is done through two main types. Alternating current and Direct Current. They are further classified into many types depending on phase and wire used. 

Alternating Current transmission AC System

Alternating Current transmission is widely used and preferred over Direct Current transmission. Depending on our requirement we can use any of the following systems.

Also Read:

Schemes Of Distribution System 

Single Line Diagram of transmission and Distribution Scheme

Three Phase three wire Ac System:

This system consists of three wires and this system is most suitable for large factories which need a bulk supply. They get the required supply, directly from the sub-station. The power is also distributed here to various points like other substations and distribution centers.

Three Phase Four Wire Scheme:

This system consists of three phases and four wires namely R, Y, B and neutral. This system is suitable for domestic purposes and small industries.

[The remaining are rarely used and also uncommon. They are used only if the requirement arises and that’s too for shorter distances only. I myself never seen the remaining systems live in my entire life.]

Two Wire Single Phase Ac System with one Conductor Earthed:

Here one terminal from the conductor is earthed. The total voltage is Vm and the root mean square value is Vm/√2 .

Two Wire Single Phase Ac System with MidPoint Earthed:

Here the mid-point of the conductor is earthed. The total voltage is 2Vm (Vm + Vm). The RMS value is 2Vm/ √2 = √2 Vm

Three Wire Single Phase Ac system:

Three Wire Two-Phase AC System:

Four Wire Two-Phase  AC System:

Two Wire dc system with Midpoint Earthed:

Three Wire DC System:

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