2B3 is Part B, Paper 3 of the six papers required for a 2nd Class Power Engineer's Certificate of Competency. It is 3 hours, 100 multiple-choice questions, and you need 65% of the total marks to pass.

It is regularly named alongside 2A2 as the hardest paper in the set, and the reason is straightforward: most 2nd Class candidates came up through mechanical plant work. Electrotechnology is not harder than thermodynamics in any absolute sense, it is simply the subject this audience has the least exposure to, and it is the biggest section on the paper.

For how 2B3 fits alongside the other five papers, see the full breakdown of all six SOPEEC 2nd Class papers.

What the syllabus actually says is on 2B3

The current SOPEEC reference syllabus lists three numbered sections for this paper:

On section weighting: SOPEEC publishes no per-topic question count for 2B3, or for any paper, so any exact split you have been quoted is an estimate. What the syllabus does show is that electrotechnology dwarfs the other two sections in scope, and Full Steam Ahead's own 2B3 course reflects it: 49 of its 84 objectives are electrical, 25 refrigeration and 10 compression. If you are budgeting study time by section, electrical work gets the majority of it.

AC theory

The foundation for everything else in the electrical section. Sine wave generation, RMS versus peak versus peak-to-peak, vector representation, R, L and C in single-phase circuits, reactance, impedance, resonance, true and apparent power, power factor and its correction, and three-phase circuits in both delta and star.

What trips people up in AC theory

Delta versus star relationships. Which of line and phase voltage are equal, which of line and phase current are equal, and where the root-three factor goes. This is the single most reliable source of lost marks in the section, and the distractors are always the other three combinations.

True versus apparent power. Watts, volt-amps and the relationship between them. The syllabus specifically names the practical importance of power factor, so expect questions about why it matters to the plant, not just how to calculate it.

Reactance behaviour. Inductive reactance rises with frequency, capacitive reactance falls. Questions test the direction of change as often as the value.

RMS by default. Unless a question says otherwise, AC values are RMS. Candidates who miss this convert when they shouldn't and land on a wrong option that exists precisely for them.

DC machines

Generators and motors: commutation, armature reaction, interpoles, compensating windings, lap and wave windings, self-excitation, voltage regulation, then motor action, torque development, back EMF, starting arrangements, braking and speed control.

What trips people up in DC machines

Armature reaction and its fixes. Interpoles and compensating windings both address it, differently. Know which does what.

Lap versus wave. Two winding arrangements with different current and voltage implications. Straightforward once studied, a coin flip if not.

Back EMF. Central to why a DC motor needs a starter and how speed control works. The syllabus asks for voltage, current and speed computation, so this section carries calculation as well as description.

Dynamic versus regenerative braking. Named separately. Both slow the machine; only one returns energy to the supply.

AC machines, transformers and protection

Alternators through to circuit-protective equipment. This is the largest single block of the electrical section and the closest to plant reality: synchronizing, parallel operation, power factor control, motor types and starting, transformer testing and connections, and the protection built around all of it.

What trips people up in AC machines

Speed, frequency and pole pairs. The relationship is examinable directly and underpins alternator and induction motor questions alike.

Synchronizing conditions. What has to match before you close the breaker, and what happens if one condition is not met. A favourite question because the consequences are concrete.

Slip. Slip and rotor speed in polyphase induction motors are named explicitly. Know the relationship and be able to compute it.

Single-phase motor types. Universal, shaded pole, split-phase, repulsion-start, reluctance-start and capacitor starting are six named things distinguished by how they start. That is the axis the questions use.

Open and short circuit tests. Which transformer loss each test measures. Regularly reversed in the answer options.

Interrupting capacity. Named on the syllabus. It is not the same as the continuous rating, and the distractors rely on candidates treating it as if it were.

Air and gas compression

The smallest section: compressor types and their applications, construction, regulation and control, drive selection and preventive maintenance, the effects of altitude, temperature and humidity, and the full ancillary set from unloaders and separators to dryers and receivers.

What trips people up in compression

Ambient effects. Altitude, temperature and humidity are called out first in the section. Know which way each one moves compressor performance and why.

Unloaders and capacity control. How a compressor is regulated at part load, and what an unloader actually does, is examinable and often assumed rather than learned.

Matching type to duty. Reciprocating, axial, centrifugal and rotary each suit different pressures and flows. Questions describe a service and ask which machine fits.

Skipping it because it is small. Ten objectives that can be covered completely in a few sittings. Complete coverage of a small section is the cheapest mark on the paper.

Industrial and commercial refrigeration

Bigger than most candidates expect, and it carries a calculation block of its own: capacities and performance, ideal versus practical cycles, theoretical piston displacement, heat pump effect, theoretical power, and pressure-enthalpy charts.

What trips people up in refrigeration

Absorption versus compression. Two different ways to move heat, with different components. Absorbers, generators and rectifiers belong to the absorption system, and a rectifier here has nothing to do with electrical rectification, which is a genuine trap on a paper that also covers electrotechnology.

Pressure-enthalpy charts. Named explicitly. Reading a P-h chart is a mechanical skill like reading steam tables, and it responds to drilling.

Theoretical piston displacement and theoretical power. Both named. These are formula-and-method questions, not concept questions.

Purging, charging and leak testing. Procedural content, examinable in its own right, and the sort of thing candidates assume they will reason out in the exam room.

Code requirements. The CSA B52 Mechanical Refrigeration Code is on the list of reference material you are permitted to bring into the exam room, which tells you the code is expected to be used rather than memorised. Practise finding things in it.

How to sequence your study for 2B3

  1. Start earlier than for any other paper, and start with AC theory. Everything else electrical stands on it, and if you are coming from the mechanical side you are learning a new subject, not revising one.
  2. Be honest about your baseline. If delta versus star and true versus apparent power are not solid, work there before touching machines. Candidates who push on regardless spend the whole study period building on sand.
  3. DC machines, then AC machines and transformers. The concepts transfer in that direction, and protection makes more sense once the machines do.
  4. Refrigeration next, with the calculations treated as their own drill. P-h chart work is a skill, not knowledge.
  5. Compression last, and finish it completely. Smallest section, quickest to close out.
  6. Timed full papers at the end. 1.8 minutes per question across a paper carrying electrical calculations, refrigeration calculations and descriptive content. See exam time management.

For total time to budget, see how long it takes to prepare for a 2nd Class exam, and the guide to SOPEEC multiple-choice traps for the distractor patterns that repeat across papers.

2B3 is commonly written last, and there is a good argument for it: nothing else in the 2nd Class set depends on it, so it can absorb the long runway it needs without holding up the other five papers. There is an equally good argument for starting the electrical reading early and writing it in the middle, so a weak baseline has time to become a strong one.

How Full Steam Ahead covers 2B3

The 2B3 course on the platform runs to 84 objectives across 10 chapters, mapped to the syllabus above: alternating current theory, direct current machines, AC generators, AC motors, transformers, electrical system protection, air and gas compression, then refrigeration systems and equipment, refrigeration safety, control and operation, and refrigeration calculations.

Electrical and refrigeration calculations are staged rather than single-answer, so a three-phase power problem or a piston displacement problem tells you which step broke instead of just marking the final number wrong. That matters more on 2B3 than anywhere else, because when the subject is unfamiliar a wrong answer with no explanation teaches you nothing. When you miss a question, the lesson that teaches that objective plays inside the results screen, and the AI tutor answers the follow-up.

2B3 is included in the 2nd Class subscription at $149/month, which covers all six papers. If you just want the source material, the power engineering textbook library on this site is free and ungated.