ECE 2207 — Electrical Machines I

Class Test (CT) Questions & Solutions (Session 2023-24)

Department of Electrical & Computer Engineering (ECE), RUET

This directory contains faithful, word-for-word digitizations of all four Class Tests (CT-01 to CT-04) conducted during the 2nd Year Even Semester (Session 2023-24). Each file includes the high-resolution paper scan, verbatim transcription, and complete step-by-step solutions with diagrams and derivations.

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1. Class Test Overview & Index

CT No.	Date	Topic Domain	Topics Tested	Marks	Full Solution File
CT-01	19/07/2026	Induction Motor	3-$\varphi$ RMF synchronous speed proof, IM operating principle	20	CT_01.md
CT-02	03/08/2026	Induction Motor	Max torque independence from $R_2$, Blocked rotor test	20	CT_02.md
CT-03	26/08/2026	Transformer	1-$\varphi$ transformer schematic & variables, EMF equation proof	20	CT_03.md
CT-04	09/09/2026	Transformer	Leakage flux effect, Phasor diagram of R-L loaded ideal transformer	20	CT_04.md

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2. Complete Question Listing

CT-01 (Held on 19/07/2026)

• Q1. Suppose that 3-$\varphi$ supply is given to an induction motor (IM). Prove that the resulting flux at stator will rotate at synchronous speed. [10 Marks, CO1, PO1]
• Q2. Explain the basic operating principle of an induction motor. [10 Marks, CO1, PO1]

CT-02 (Held on 03/08/2026)

• Q1. Justify the following: "The value of rotor resistance does not alter the value of the maximum torque but only the value of slip at which it occurs." [10 Marks, CO1, PO1]
• Q2. Explain the blocked rotor test of an induction motor. Also enlist the necessities of performing this test. [10 Marks, CO1, PO1]

CT-03 (Held on 26/08/2026)

• Q1. Schematically represent a single-phase transformer assuming the primary winding is connected to a sinusoidal voltage source, while the secondary winding is connected to a load. Also identify and label the variables associated with the primary and secondary sides of the transformer in the schematic. [10 Marks, CO1, PO1]
• Q2. Consider an ideal single-phase transformer operating under the following assumptions:
  • The permeability of the core is constant over the range of transformer operation, and hence the reluctance of the core is constant.
  • There is no leakage flux; therefore, the same sinusoidally varying flux links both the primary and secondary windings. If the core flux is sinusoidal with frequency $f$ and maximum value ${\Phi }_m$, prove that: $$E_1=4.44f{N}_1{\Phi }_m\text{and}{E}_2=4.44f{N}_2{\Phi }_m$$ Variables having their usual meanings. [10 Marks, CO1, PO1]

CT-04 (Held on 09/09/2026)

• Q1. With the help of schematic representation, explain the effect of leakage flux on the transformer operation. [10 Marks, CO1, PO1]
• Q2. Draw the phasor diagram of a R-L loaded ideal transformer. Also describe each step while drawing. [10 Marks, CO1, PO1]

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3. Exam Analysis & Strategic Value

These class tests directly reflect the teacher's exam focus. Every single topic tested in these four class tests represents a high-frequency question in RUET semester final examinations:

CT Question	Topic	Frequency in 7 Semester Finals	Direct Semester Final Appearances
CT-01 Q1	3-$\varphi$ RMF proof ($1.5{\Phi }_m$)	6 / 7 (86%)	2024 Q5a, 2023 Q5a, 2021 Q5a, 2020 Q5a, 2018 Q5a, 2017 Q5a
CT-01 Q2	Induction motor operating principle	Fundamental	Appears across all theoretical sections
CT-02 Q1	$T_{\text{max}}$ independent of $R_2$	6 / 7 (86%)	2024 Q6a, 2023 Q6b, 2021 Q6a, 2020 Q6a, 2019 Q6a, 2018 Q6a
CT-02 Q2	Blocked rotor test & parameter extraction	4 / 7 (57%)	2023 Q7a, 2020 Q7b, 2018 Q7b, 2017 Q7b
CT-03 Q1	Transformer physical schematic	High	2024 Q1b (exciting core schematic)
CT-03 Q2	Transformer EMF equation ($4.44fN{\Phi }_m$)	4 / 7 (57%)	2024 Q1b, 2023 Q1b, 2021 Q1a, 2019 Q1a
CT-04 Q1	Leakage flux & leakage reactance	High	Core equivalent circuit derivation in 2024 Q2a, 2020 Q2a
CT-04 Q2	R-L loaded transformer phasor diagram	4 / 7 (57%)	2024 Q2b, 2021 Q2b, 2018 Q2a, 2017 Q2a

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4. Directory Structure

CT_Questions/
├── AGENTS.md                  # Quick lookup table for AI agents
├── README.md                  # This master index and analysis document
├── CT_Questions.md -> README.md
├── CT_01.md                   # CT-01 questions, transcript, scan, and solutions
├── CT_02.md                   # CT-02 questions, transcript, scan, and solutions
├── CT_03.md                   # CT-03 questions, transcript, scan, and solutions
├── CT_04.md                   # CT-04 questions, transcript, scan, and solutions
└── diagrams/
    ├── ct01_question_paper.jpg
    ├── ct02_question_paper.jpg
    ├── ct03_question_paper.jpg
    └── ct04_question_paper.jpg

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5. Related Vault Resources

• Full Exam Analysis & Heatmap: ECE_2207_Question_Analysis.md
• Previous Semester Finals: PrevYearQuestions/README.md
• Classroom Notes: ClassNoteByRaidah/00_Index_and_Topic_Map.md
• Teacher Lecture Slides: SlidesByMaam/map.md
• Course Syllabus: Syllabus.md