3B2 is one of four papers required for a 3rd Class Power Engineer's Certificate of Competency. Like every SOPEEC paper it is 100 multiple-choice questions and you need 65% to pass, within a 3-hour time limit. There is no written-answer component. Each of the four 3rd Class papers, 3A1, 3A2, 3B1 and 3B2, passes or fails on its own, with no averaging between them.
For where 3B2 sits against the other three papers, see the 3rd Class power engineering exam guide, and for how this level compares to the one above it, see 3rd Class vs 2nd Class power engineering.
What the syllabus actually says is on 3B2
SOPEEC does not publish a per-topic question count for 3B2, or for any other paper. It states the format, the duration and the 65% pass mark and nothing more. Any exact split you have been told is someone's estimate, not a published figure, and studying to a guessed weighting is a good way to leave a real topic thin. The safer approach is to cover the paper's full breadth, because every chapter in the course is fair game.
3B2 runs across fifteen chapters that group into seven blocks: steam turbines and condensers, gas turbines, internal combustion engines and cogeneration, compressors, refrigeration, heat exchangers with cooling towers and fired heaters, and wastewater treatment with plant maintenance and administration.
Steam turbines and condenser systems
Steam turbine principles and design, turbine auxiliaries and operation, and turbine condenser systems. This is rotating equipment on the steam side, from theory through to the equipment that removes heat from the exhaust.
What trips people up in steam turbines and condensers
Principles versus the specific design in front of you. Impulse and reaction principles explain why a turbine is built the way it is. Questions test whether you can reason from the principle to a design feature, not just recite which principle a given machine uses.
Auxiliary systems traced as a chain, not a parts list. Lubricating oil, governing and control auxiliaries interact with each other and with the turbine's operating state. A question about an auxiliary fault is usually asking what happens next in the system, not asking you to name the auxiliary.
Condenser performance reasoned from a symptom. Loss of vacuum, cooling water problems and air in-leakage each have a different signature. Condenser systems sit in their own chapter here because the reasoning from symptom to cause is a skill on its own.
Gas turbines
Gas turbine principles and designs, and gas turbine auxiliaries and operation. A separate machine family from steam turbines, sharing the word "turbine" but not much else in construction or cycle.
What trips people up in gas turbines
Confusing gas turbine and steam turbine auxiliaries. Because both chapters use turbine vocabulary, it is easy to import a steam turbine answer into a gas turbine question. The compressor, combustor and hot gas path on a gas turbine have no steam-side equivalent.
Design feature tied to its actual purpose. Gas turbine design choices exist to manage the cycle's efficiency and its operating temperature limits. Know why a specific design feature exists, not just that it exists.
Internal combustion engines and cogeneration
Internal combustion engines and cogeneration systems and operation sit together because a cogeneration plant is frequently built around a reciprocating engine or a turbine recovering its own waste heat for another use.
What trips people up in IC engines and cogeneration
Engine operating and safety detail treated as generic. IC engine questions test specific operating and maintenance knowledge, not a general sense of how an engine works. Read the chapter for the specific failure modes and safety practices it names.
Cogeneration as a system, not a single machine. Cogeneration questions test how the prime mover, the heat recovery equipment and the second use of that heat fit together. A cogeneration question that only asks about the engine or turbine in isolation is testing half the picture.
Compressors
Compressor theory and designs, and compressor auxiliaries and operation. Theory and hardware in one chapter, the supporting systems and operating practice in the next.
What trips people up in compressors
Compressor type matched to the duty it performs. Different compressor designs suit different pressure ratios and flow conditions. Questions describe a duty and ask which design fits, the same reasoning pattern that shows up across this whole paper.
Auxiliary systems as protection, not decoration. Compressor auxiliaries exist to protect the machine from conditions specific to compression, and questions test whether you know what each auxiliary is protecting against.
Refrigeration
Refrigeration principles and systems, and refrigeration auxiliaries and operation. Two chapters, one covering the cycle and system types, the other covering what keeps the system running safely.
What trips people up in refrigeration
Cycle analysis under an unfamiliar phrasing. Refrigeration cycle questions describe a state change or a component's effect on the cycle and ask you to identify the consequence. Candidates who have only memorized a diagram of the cycle, rather than what happens at each stage and why, lose marks here.
System type affecting the answer. Refrigeration systems are not all built the same way, and a question's correct answer depends on which system type is described in the stem. Read the stem for the system type before answering.
Auxiliaries treated separately from the cycle they protect. Refrigeration auxiliaries and operation is its own chapter for a reason: safe operation of a refrigeration system depends on auxiliary equipment as much as the main cycle components, and the exam treats that knowledge as separately examinable.
Refrigerant behaviour confused with general steam or gas behaviour. Candidates coming to 3B2 with a strong steam turbine and boiler background sometimes carry steam-side intuition into refrigeration questions, where pressure, temperature and phase relationships work under a different set of properties. Study refrigeration on its own terms rather than as an extension of the steam material earlier in this paper.
Heat exchangers, cooling towers and fired heaters
Heat exchangers and cooling towers share a chapter, and fired heaters get their own. Both are equipment that transfers heat, one without combustion and one built around it.
What trips people up in heat exchangers, cooling towers and fired heaters
Heat exchanger type matched to service. Different exchanger constructions suit different fluids and fouling tendencies. Questions test the match, the same pattern that recurs across every equipment chapter on this paper.
Fired heaters as combustion equipment, not just a heat exchanger with a flame. Fired heaters bring combustion, draft and firing considerations into the same equipment class as the heat exchangers next to them, and treating a fired heater as a plain heat exchanger question misses the combustion-side detail the exam tests.
Wastewater treatment and plant maintenance and administration
The paper closes with wastewater treatment and plant maintenance and administration, the two chapters candidates are most likely to leave for last because neither feels like core rotating equipment.
What trips people up in wastewater treatment and plant administration
Wastewater treatment underestimated because it feels environmental rather than mechanical. It is a named chapter with its own examinable content, and skimming it because it does not involve a turbine or a compressor is a common way to leave easy marks on the table.
Administration content skipped as paperwork. Plant maintenance and administration covers the record-keeping and administrative side of running a plant. It reads as less technical than the rest of the paper, which is exactly why it is a cheap, complete section for anyone willing to study it properly.
How to sequence your study for 3B2
3B2's real difficulty is breadth: four separate machine families, steam turbines, gas turbines, IC engines and compressors, each with its own theory and its own operating practice, plus refrigeration and a set of plant systems on top. Treating it like a single subject is the mistake. Treat it like four or five smaller courses studied in sequence.
That breadth is also why it rewards candidates who separate the machine families cleanly in their own notes before they try to compare them. A study plan that jumps between a turbine question, a compressor question and a refrigeration question in the same session invites exactly the kind of cross-family confusion the exam's distractors are built to catch. Block your study time by machine family first, and only mix them once each one is solid on its own.
- Steam turbines and condensers first. The largest and most detailed block, and the one most 3rd Class candidates have the most workplace exposure to.
- Gas turbines next, deliberately kept separate from steam turbine review. Study them back to back with steam turbines only after you can keep the two machine families straight, so you do not blur their auxiliaries.
- IC engines and cogeneration together. The cogeneration chapter builds directly on the engine chapter before it.
- Compressors and refrigeration as their own pass. Neither depends heavily on the turbine and engine material above, so they can be studied as a self-contained block once the machine families are solid.
- Heat exchangers, cooling towers, fired heaters, wastewater and plant administration last, and completely. Smaller in scope individually, easy to shortchange, and easy to finish once the four machine families are done.
- Timed full papers at the end. See exam time management and what to expect on exam day.
The guide to SOPEEC multiple-choice traps covers the distractor patterns that repeat across every paper at every level, including the equipment-to-duty matching pattern that runs through most of 3B2.
3B2 pairs naturally with 3B1, the boiler plant and pressure vessel paper. Together they make up the Part B half of 3rd Class.
How Full Steam Ahead covers 3B2
The 3B2 course on the platform is built directly from the fifteen chapters above, grouped the same way this guide groups them: steam turbines and condensers, gas turbines, IC engines and cogeneration, compressors, refrigeration, heat exchangers with cooling towers and fired heaters, then wastewater treatment and plant maintenance and administration. The question bank behind 3B2 runs to 925 questions, the deepest of the four 3rd Class papers.
Because 3B2 spans so many separate machine families, the platform tracks your progress by chapter rather than treating the paper as one undifferentiated pool, so you can see which of the four machine families still needs work instead of guessing. When you miss a question, the lesson for that objective plays inside the results screen and the AI tutor takes the follow-up question, which on this paper is usually some version of what one system's failure does to the rest of the plant.
3B2 is included in the 3rd Class subscription at $99/month, which covers all four 3rd Class papers. If you just want the source material, the power engineering textbook library on this site is free and ungated.