Three-Phase AC Generation & Systems is one of 9 topics in the Grade 12 Electrical Technology CAPS syllabus, covered across 3 lessons on Study Vault. Below are real practice questions from this topic with full worked answers.
Sample practice questions
Easy
1. By how many electrical degrees are the three windings of a three-phase generator spaced apart?
120 degrees
90 degrees
180 degrees
360 degrees
Answer: 120 degrees — The three windings of a three-phase generator are spaced 120 electrical degrees apart, producing three voltage waveforms offset by one-third of a cycle from each other.
Easy
2. Which is a key advantage of three-phase power delivery compared to single-phase, for the same conductor size?
Three-phase power delivers significantly more power for the same conductor size
Three-phase power always requires fewer conductors than single-phase
Three-phase systems are always cheaper to install than single-phase
Three-phase power cannot be transmitted over long distances
Answer: Three-phase power delivers significantly more power for the same conductor size — For the same physical size of conductor and equipment, three-phase power delivers significantly more power than single-phase.
Medium
3. Name the type of diagram that shows three voltage phasors spaced 120 degrees apart, used to represent three-phase generation.
Answer: phasor diagram — A phasor diagram represents the three voltage phasors of a three-phase system, spaced 120 degrees apart.
