Troisième année14 items · about 3 hours
Third-year electrical apprentice
Third year is where the trade turns three-phase. These lessons take wye and delta apart, build transformer banks, spin up an induction motor and start it five ways, turn a relay circuit into PLC ladder logic, and then walk the commercial jobsite — protection, grounding, wiring methods, prints and fire alarm. Each lesson ends in a short quiz; pass it at 80% and it is ticked off here.
Comes after: First year · Second year
The lessons, in order
- Wye and delta: line vs phase The two ways three windings are joined, and the √3 that separates line from phase voltage and current.
- Unbalanced loads and neutral current Why a balanced wye neutral carries nothing, what it carries when the loads are uneven, and the harmonics that break the rule.
- Three-phase power and power factor kW, kVA and kVAR on a three-phase load: the power triangle, the √3 formula and what a poor power factor costs.
- Three-phase transformer connections Delta-wye, wye-wye, delta-delta and wye-delta: what each gives you on the secondary and where you meet it.
- Polarity, phase shift and open delta Additive and subtractive polarity, the 30° shift through a delta-wye, and running a bank on two cans.
- How an AC induction motor works The rotating field, synchronous speed, slip, and reading the nameplate numbers that come out of them.
- Motor starting methods Across-the-line, primary resistor, autotransformer, wye-delta, soft starter and drive — what each trades away.
- Intro to PLCs: from relays to ladder logic Inputs, outputs, the scan cycle, and how a hard-wired start/stop becomes three rungs of ladder logic.
- Overcurrent protection and coordination Overload versus short circuit, reading a time-current curve, and what "selective coordination" is trying to do.
- Grounding and bonding as a system System grounding, equipment bonding, the fault return path and separately derived systems, end to end.
- Commercial wiring methods EMT, rigid, flex, cable tray, armoured cable and busway — what each is good at and the questions to ask of the book.
- Reading commercial and industrial prints The drawing set, single-lines, risers, panel and luminaire schedules, and finding your way around a sheet.
- Fire alarm basics Initiating and notification devices, supervision and end-of-line devices, conventional versus addressable.
- Third-year review quiz Every third-year question in one place, mixed, with explanations. Filter to a topic you are weak on.
Tools for this year
- Three-phase power calculator kW, kVA, kVAR and amps from any one of them, with voltage and power factor — three-phase or single.
- Transformer full-load current & ratio Primary and secondary full-load amps, line and turns ratio, and the current in each winding for delta or wye.
- Motor synchronous speed & slip Synchronous speed from frequency and poles, the pole count a nameplate speed implies, slip and rotor frequency.
- Delta ↔ wye impedance conversion Turn a delta of three impedances into the equivalent wye, or back — balanced or not.
How to use this year
Go in order the first time — each lesson leans on the one before, and the three-phase lessons at the top feed everything after them. Every number on these pages is physics or a practice figure; ratings, sizes and limits come from your own code book (CSA C22.1 in Canada, the NEC in the US), which is the book your exam uses. When a topic has a hands-on side, the lesson points you at the motor control labs or one of the tools above.
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Un petit mot sur les outils qui vous conviennent — par courriel, facultatif
Laissez votre courriel et cochez la case pour un petit mot, au plus toutes les deux semaines, sur les outils, exercices et schémas qui vont avec ce que vous étudiez — ici et sur bentright.com et fieldcalc.net. Une seule liste pour les trois, un clic pour la quitter, et rien n’est envoyé avant que vous confirmiez depuis votre boîte de réception.