# Three phase circuits

##### Video Lessons & Revision Notes

3 Phase Circuits - Basic Concepts
1. 3 Phase Circuits - Basic Concepts
In this 28 mins Video Lesson
Generation of 3 Phase Power, Phase Sequence, Sum of Generated Voltages in 3 Phase System , Need for 3 Phase Power, and other topics.
3 Phase Circuits - Terminology
2. 3 Phase Circuits - Terminology
In this 13 mins Video Lesson
3 Phase Connections, Star / Wye Connection, Delta / Mesh Connection, Balanced Load, Line / Line - Line Voltage, Line-Neutral Voltage, Phase Voltage, Line Current, Phase Current, and other topics.
3 Phase Star-Star System
3. 3 Phase Star-Star System
In this 42 mins Video Lesson
A Wye-Wye 3 Phase System, Phase Voltages in Star System, Phase and Line Currents in Wye System, Line Voltages in Wye System, Relationship between Phase and Line Quantities (Phasor Diagram) in Wye System, One Line Diagram in Balanced System, Power in Wye System, and other topics.
3 Phase Delta-Delta System
4. 3 Phase Delta-Delta System
In this 22 mins Video Lesson
A Delta-Delta 3 phase System, Phase and Line Voltages in Delta System, Phase Currents in Delta System, Line Currents in Delta System, Relationship between Line and Phase Quantities (Phasor Diagram) in Delta System, Power in Delta System, and other topics.
3 Phase Transformations and Typical Problems
5. 3 Phase Transformations and Typical Problems
In this 26 mins Video Lesson
Delta - Wye Load Transformations, Delta - Wye Source Transformations, Typical Problems on 3 - Phase Systems, and other topics.
Measuring Power in 3 Phase Systems - 2 Wattmeter Method
6. Measuring Power in 3 Phase Systems - 2 Wattmeter Method
In this 28 mins Video Lesson
Wattmeter - How it Works, 3 Phase Power using 2 Wattmeter Method, Power Factor using 2 Wattmeter Method, and other topics.

### Revision Notes

Three phase voltage and current generation, star and delta connections (balanced load only), relationship between phase and line currents and voltages, Phasor diagrams, Basic principle of wattmeter, measurement of power by two wattmeter method.