NTPC AE Operation Previous Year Paper 2025: Exam Analysis, Pattern & Model Questions
NTPC has been conducting the Assistant Executive (Operation) recruitment on a fixed-term contract basis annually since 2024-25. The most recent completed exam was held on 27 April 2025 under Advertisement No. 04/2025 (400 posts). The 2026 cycle (Advt. 05/26, 250 posts) follows the same structure. This article covers the 2025 exam pattern, section-wise analysis based on candidate feedback, and 15 representative model questions that reflect the actual difficulty and type of questions asked.
👉 NTPC AE Operation Syllabus 2026 — complete topic list for Mechanical and Electrical candidates
NTPC AE Operation — Exam History
| Advertisement | Year | Posts | Exam Date | Status |
|---|
| Advt. 04/2025 | 2025 | 400 (Mech + Elec) | 27 April 2025 | Completed — results announced |
| Advt. 05/2026 | 2026 | 250 (Mech + Elec) | To be announced | Active — last date 7 May 2026 |
NTPC does not officially release question papers after the exam. However, based on candidate feedback shared on forums and prep platforms after the April 2025 exam, the pattern is consistent: 200 questions, 200 marks, 120-minute duration with no confirmed negative marking.
2025 Exam Pattern — Section-wise Analysis
| Section | Questions | Marks | Remarks from 2025 Feedback |
|---|
| Technical Knowledge (Mechanical or Electrical) | 100 | 100 | Predominantly application-based; theory questions were fewer than expected. Power plant operations were heavily tested for Mechanical. |
| General Awareness | 50 | 50 | Current affairs from 2024-25 (power sector, government schemes, environment) + static GK on Indian polity, economy, science. |
| Reasoning & General Intelligence | 50 | 50 | Moderate difficulty. Series, coding-decoding, analogies, direction problems. Time management was key — 30 minutes for 50 questions. |
Candidate consensus from the 2025 exam: Technical section was the differentiator. GA and Reasoning were manageable within the time limit. The Technical questions for Mechanical candidates were heavily weighted toward Power Plant Engineering and Thermodynamics — confirming the operational nature of the role.
👉 NTPC AE Operation Eligibility 2026 — B.E./B.Tech + 1 year power plant experience — detailed breakdown
Model Questions — Mechanical (Technical Section)
These questions are representative of the type and difficulty reported in the 2025 NTPC AE exam. Use them to benchmark your preparation level.
Q1. In a Rankine cycle, the thermal efficiency is improved most effectively by:
- Increasing the condenser pressure
- Superheating the steam before turbine entry
- Reducing the boiler pressure
- Decreasing feed pump work
Answer: B — Superheating raises the average temperature at which heat is added, increasing efficiency and improving steam quality at turbine exit — reducing blade erosion.
Q2. A Circulating Fluidised Bed Combustion (CFBC) boiler maintains bed temperature at:
- 350–450°C
- 550–650°C
- 800–900°C
- 1100–1200°C
Answer: C — CFBC operates at 800–900°C — lower than pulverised coal combustion (1300–1500°C), which significantly reduces NOx and SOx formation.
Q3. The Economiser in a thermal power plant is used to:
- Superheat steam after the drum
- Preheat boiler feed water using flue gas heat
- Remove dissolved oxygen from feed water
- Control turbine inlet steam temperature
Answer: B — Economisers recover heat from flue gases leaving the boiler and use it to preheat feed water, improving overall boiler efficiency by 5–10%.
Q4. Which instrument measures steam flow in a high-pressure main steam line?
- Rotameter
- Venturi meter or orifice plate with DP transmitter
- Turbine flow meter
- Float-type flow meter
Answer: B — Differential pressure-based devices (orifice plates, venturi meters) are standard for steam flow measurement in power plants due to high pressure and temperature conditions.
Q5. In a cooling tower, water can theoretically be cooled to the:
- Dew point of ambient air
- Dry bulb temperature of ambient air
- Wet bulb temperature of ambient air
- Saturation temperature at atmospheric pressure
Answer: C — The wet bulb temperature is the theoretical lower limit for cooling tower outlet water temperature. In practice, the approach temperature keeps actual outlet 3–5°C above wet bulb.
Model Questions — Electrical (Technical Section)
Q6. The Buchholz relay is used for protection of:
- Air-cooled dry-type transformers
- Oil-immersed power transformers
- High-voltage switchgear
- Transmission lines
Answer: B — Buchholz relays detect gas accumulation from incipient faults (insulation breakdown, arcing) in oil-immersed transformers. They cannot be used in dry-type transformers.
Q7. In a 3-phase induction motor, if slip s = 4%, the rotor copper loss as a fraction of air gap power is:
- 96%
- 8%
- 4%
- 2%
Answer: C — Rotor copper loss = s × Air gap power. At s = 4%, rotor copper loss = 4% of air gap power. Mechanical output = (1-s) × air gap power = 96%.
Q8. A distance relay in a transmission line protection scheme operates when:
- Line current exceeds a set threshold
- The apparent impedance seen by the relay falls within the operating circle
- Voltage drops below a set level
- Both overcurrent and undervoltage occur together
Answer: B — Distance relays measure the ratio V/I at the relay point. When a fault occurs, impedance drops and enters the relay's operating zone, causing it to trip.
Q9. The per-unit (p.u.) impedance of a transformer rated 50 MVA, 10% leakage reactance, when referred to a 100 MVA base is:
- 5%
- 10%
- 20%
- 25%
Answer: C — Z_pu(new) = Z_pu(old) × (MVA_base_new / MVA_rated) = 0.10 × (100/50) = 0.20 p.u. = 20%
Q10. SCADA in the context of a thermal power plant stands for:
- System Control and Data Acquisition
- Signal Control and Data Automation
- Supervisory Control and Data Acquisition
- Systematic Command and Data Application
Answer: C — SCADA systems are used in power plants for real-time monitoring and control of plant processes — boilers, turbines, generators, auxiliary systems.
Model Questions — General Awareness
Q11. India's renewable energy installed capacity target by 2030 is:
- 300 GW
- 400 GW
- 500 GW
- 600 GW
Answer: C — India pledged 500 GW of non-fossil fuel installed capacity by 2030 at COP26 as part of its Nationally Determined Contributions (NDCs).
Q12. The "PM Surya Ghar: Muft Bijli Yojana" launched in 2024 is related to:
- Coal power plant expansion
- Rooftop solar installation for households
- Electric vehicle charging infrastructure
- Hydro power development
Answer: B — PM Surya Ghar provides subsidies for rooftop solar panels on residential buildings, targeting 1 crore households and providing up to 300 units of free electricity per month.
Q13. NTPC's Green Energy subsidiary focuses on:
- Nuclear power
- Wind and solar renewable energy
- Gas-based power plants
- Hydroelectric projects only
Answer: B — NTPC Green Energy Limited (NGEL) was incorporated to develop NTPC's renewable energy portfolio across solar, wind, and green hydrogen segments.
Model Questions — Reasoning
Q14. In the series 3, 7, 15, 31, 63, ___, the next term is:
- 95
- 127
- 125
- 131
Answer: B — Pattern: each term = 2 × previous term + 1. (3×2+1=7, 7×2+1=15, 15×2+1=31, 31×2+1=63, 63×2+1=127)
Q15. A person starts from point A, walks 5 km North, turns right and walks 3 km East, then turns right again and walks 5 km South. How far is the person from the starting point?
- 5 km
- 8 km
- 3 km
- 13 km
Answer: C — After walking 5N, 3E, 5S — the N and S movements cancel. Net displacement is 3 km East from starting point.
How to Use Previous Year Papers Effectively
- Identify weak topics first: Take a timed mock test using the model questions above. Any topic where you score below 60% needs focused revision before attempting more mocks.
- Simulate exam conditions: Set a 120-minute timer. Do not pause. The real pressure of the NTPC exam comes from managing 200 questions in 120 minutes — roughly 36 seconds per question.
- Build a topic error log: After each mock, note which topics produced the most wrong answers. Prioritise revising those topics over simply taking more tests.
- Where to find additional papers: NTPC does not officially release question papers. Candidates who appeared in the April 2025 exam shared question memory PDFs on preparation platforms. Search for "NTPC AE Operation 2025 question paper" on major preparation websites to access these unofficial compilations.
Frequently Asked Questions
Q: Did NTPC release official answer keys for the 2025 exam?
NTPC does not follow the SSC/RRB model of publicly releasing answer keys. Results are published directly without an answer key challenge window. This means if you disagree with an answer, there is no formal mechanism to challenge it — unlike UPSC or SSC where candidates can object to questions.
Q: What was the cut-off for the 2025 NTPC AE Operation exam?
NTPC has not officially published cut-off marks for the 2025 cycle. Based on the difficulty level reported by candidates and the number of posts (400), the general expectation from candidate forums was 130–150 out of 200 for the General category. However, this is unofficial feedback — treat it as an indicative benchmark, not an official figure.
Q: How many attempts are there for NTPC AE Operation?
There is no stated attempt limit. As long as you meet the age and qualification criteria at the time of each advertisement, you can apply for every cycle. Since NTPC has been recruiting annually (2025, 2026), candidates who did not clear the 2025 exam should apply for the 2026 cycle while continuing preparation.
Topic-wise Score Targets for NTPC AE CBT
Setting section-level targets before the exam removes guesswork on the day. Based on the 2025 exam pattern and the number of posts (250 in 2026), here are realistic targets for a competitive score:
| Section | Total Marks | Target Score | Safe Score | Notes |
|---|
| Technical (Mechanical or Electrical) | 100 | 72–80 | 65 | This is the differentiating section. Below 60 makes overall selection very difficult. |
| General Awareness | 50 | 35–40 | 30 | Power sector news (2025-26) and government schemes on energy are high-probability topics. |
| Reasoning & General Intelligence | 50 | 38–44 | 33 | Series, coding-decoding, direction problems, blood relations — all solvable within time. |
| Total | 200 | 145–164 | 128 | General category realistic safe score based on 400-post 2025 cycle feedback. |
These targets assume the same difficulty distribution as the 2025 exam. If the 2026 paper is easier (which sometimes happens in the second year of a recruitment cycle), the cut-off may be higher — so prepare to exceed these targets rather than just meet them.
30-Day Revision Plan for NTPC AE Operation 2026
| Week | Technical Focus | Non-Technical Focus | Daily Practice |
|---|
| Week 1 | Thermodynamics + Steam Cycles (Mech) or Electrical Machines (Elec) | Power sector current affairs 2024-25 (NTPC, NPCIL, renewable targets) | 15 Technical + 5 GA + 5 Reasoning MCQs |
| Week 2 | Power Plant Engineering + Boilers (Mech) or Power Systems + Protection (Elec) | Indian polity, economy basics + environment (Paris Agreement, COP pledges) | 20 Technical + 8 GA + 8 Reasoning MCQs |
| Week 3 | Fluid Mechanics + Heat Transfer (Mech) or Control Systems + Measurements (Elec) | Previous year GA questions from 2025 exam compilations online | Full section timed tests (60 min per section) |
| Week 4 | Full-length mock tests only | Review error log from weeks 1-3; revise only weak topics | 2 full 200-question mocks in exam conditions |
Recommended Resources for NTPC AE Operation Preparation
- Technical (Mechanical): R.K. Rajput — Thermal Engineering; P.K. Nag — Engineering Thermodynamics; R.K. Bansal — Fluid Mechanics. These three books cover 70%+ of the 2025 Technical section syllabus.
- Technical (Electrical): B.L. Theraja — Electrical Technology (Vol. 1 & 2); Nagsarkar & Sukhija — Electrical Machines; Stevenson — Elements of Power System Analysis. Focus chapters: Transformers, Induction Motors, Protection Systems.
- General Awareness: Monthly current affairs digest from any major prep platform focusing on energy and infrastructure. Static portion: Lucent GK is sufficient for NTPC-level GA.
- Reasoning: R.S. Aggarwal — Verbal and Non-Verbal Reasoning. Practice the chapter on Arrangements and Series — these appear most frequently in NTPC Reasoning.
Frequently Asked Questions
Q: Is NTPC AE Operation exam online (CBT) or offline?
Computer-Based Test (CBT) — conducted at NTPC-designated exam centres across major cities. Candidates choose their preferred city at the time of application. The 2025 exam was conducted at centres in Delhi, Mumbai, Hyderabad, Chennai, Kolkata, Bhopal, Jaipur, and other tier-1 and tier-2 cities.
Q: How many model question papers are available for NTPC AE Operation online?
Very few officially structured papers exist because NTPC conducts this exam only annually and does not release papers. After the April 2025 exam, candidates shared approximately 3–4 memory-based question compilations on platforms like Telegram preparation groups and study forums. Searching "NTPC AE Operation 04/2025 memory-based question paper" will surface these. Quality varies — treat them as practice material, not exact reproductions.
Q: Can Electrical Engineering candidates answer Mechanical questions or vice versa?
No. The Technical section in NTPC AE Operation is post-specific. When you apply, you choose either Mechanical or Electrical stream. Your question paper is entirely for that stream — there is no option to attempt questions from the other stream. Make sure your application stream matches your strongest subject area.
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