- Protective Relaying: Principles and Applications by J. Lewis Blackburn and Thomas J. Domin, 3rd Edition, CRC Press
- The method of symmetrical components was discovered by Charles L. Fortescue.
- In Symmetrical components, the sequence quantities i.e. Voltage and Current are LINE to NEUTRAL or LINE TO GROUND (opposed to Power system where L-L Voltages are used).
- Positive sequence is a-b-c, 120 deg counterclockwise; Negative sequence is a-c-b, 120 deg reversed to positive sequence; Zero sequence is always in phase
- Phasors always exist as a set of 3 but never alone.
- Unbalanced 3-Ph quantities are divided into the seque nce component as they are independent components in a balanced system network.
- Electric power systems are balanced or symme trical from the generators to the point
of single-phase loading, except in an area of a fault.