Free mock exam
Three-Phase Systems — Level 3 Electrical Science Practice
Free topic-focused mock exam: all 30 questions on Three-Phase Systems, drawn from the wider Level 3 Electrical Science bank. 35-minute timer, 70% to pass, worked explanation on every question. Use this when you've taken the full mock once and want to drill the topics you got wrong.
- Questions
- 30
- Time limit
- 35 min
- Pass mark
- 70% · 21/30
- Question bank
- 30
Free, no sign-up. Retake as many times as you like — the questions are reshuffled, with the answer order changed.
Sample questions
01What is the phase difference between phases in a three-phase supply?
- A60°
- B180°
- C90°
- D120°
Why: In a three-phase supply, the three phases are displaced by 120° (one-third of a cycle) from each other.
02What is the UK three-phase line voltage?
- A230V
- B415V
- C440V
- D400V
Why: UK three-phase line voltage (between phases) is 400V. Phase voltage (to neutral) is 230V. Ratio is √3 (1.732).
03What is the relationship between line and phase voltage in a star connection?
- AVL = Vp
- BVL = Vp × √3
- CVL = Vp × 3
- DVL = Vp / √3
Why: In a star (wye) connection: VL = Vp × √3. UK: 230V phase × 1.732 = 400V line.
Common questions
Is the Three-Phase Systems mock exam free?
Yes — 100% free, no sign-up needed. Questions are pulled at random from a substantial bank, with a worked explanation on every question after you submit.
Can I retake the mock exam?
Yes. Every attempt picks a different random selection and reshuffles the options, so each retake gives you genuinely new questions. No limit on retakes.
Does this count towards the real qualification?
No — this is independent practice material. To gain the actual qualification you need to sit the official assessment through an approved provider.
