An Essential Power System in HD

This is a summary of the essential material on a power system flow of active and reactive power between an AC source and a source (a factory) connected by a cable (feeder) represented by its resistance and inductive reactance in series.
ERRATA: In the copy-and-paste frenzy of equations, one typo escaped the proofreading. The cosine law formula near 14:44 the last term should read 2VfVcbl cos alpha. Thanks to my students, the typo was caught.