Explain the method of symmetrical components for unbalanced system analysis.

Symmetrical components decompose unbalanced three-phase quantities into three balanced sets: positive sequence (normal rotation), negative sequence (reverse rotation), and zero sequence (in-phase). Transformation uses the 'a' operator (120-degree phase shift). This technique simplifies fault analysis since sequence networks are decoupled and faults impose specific boundary conditions. Sequence impedances differ in rotating machines. It is essential for protective relay coordination and fault current calculations.