Electrical Machines I (BEE402) - AKTU Question Paper 2025-26
B.Tech · Semester 4 · Free PDF Download
This is the official AKTU Electrical Machines I Previous Year Question Paper for B.Tech Semester 4, academic session 2025-26. Published by Dr. A.P.J. Abdul Kalam Technical University (AKTU/UPTU), Lucknow. Free PDF download — no login required.
Course:B.Tech
Semester:Semester 4
Session:2025-26
University:AKTU / UPTU
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Questions Asked in 2025-26
Electrical Machines I (BEE402) — extracted question text · 70 marks · 3 Hours
Section AAttempt all questions in brief. 02 x 7 = 14
- aDefine co-energy in an electromechanical system
- bWhat is armature reaction in DC machines?
- cA DC motor draws 20 A from a 220 V supply. Armature resistance is 0.5 Ω. Find back EMF
- dDifferentiate between 3-point and 4-point starters
- eDraw phasor diagram of ideal transformer at no load condition
- fWhat is voltage regulation in a transformer?
- gGive conditions for three parallel operation of three phase transformer
Section BAttempt any three of the following: 07 x 3 = 21
- aShow that the field energy in a linear magnetic system is given by
- bDescribe the process of commutation. Also explain its types and the methods to improve the commutation in DC machines
- cA 250 V dc shunt motor has an armature resistance of 0.5Ω and a field resistance of 250 Ω. When driving a constant torque load at 600 rpm, the motor draws 21 A. What will be the new speed of the motor if an additional 250 Ω resistance is inserted in the field circuit?
- dThe maximum efficiency of a 100 kVA, 1100/440 V, 50 Hz transformer is 96%. This occurs at 75% of full load at 0.8 power factor lagging. Calculate the efficiency of transformer at half load and at 0.6 power factor lagging
- eDescribe the 3-phase to 2-phase conversion in transformers with suitable diagram. Also, derive the expression for positioning of neural point
Section CAttempt any one part of the following: 07 x 1 = 07
- aDerive the expression for force and torque in a singly excited magnetic system
- bExplain the generation of EMF in electrical machines with cylindrical air gap. (SEM. IV) THEORY EXAMINATION 2025-26 ELECTRICAL MACHINES-I
- aExplain the armature reaction in DC generators using armature and field MMF waveforms. Describe the effects of armature reaction?
- bDiscuss commutation and methods of improving commutation
- aA 230V DC series motor develops its rated output at 1500rpm while taking 20A. Armature and series field resistances are 0.3 Ω and 0.2 Ω respectively. Neglecting saturation, determine the resistance that must be added to obtain rated torque i) at starting and ii) at 1000 rpm
- bExplain Swinburne’s test to calculate no-load losses in a DC machine. State its limitations over Hopkinson’s test
- aDescribe the construction, working, and advantages of autotransformers
- bA 200 kVA, 2000/440 V, 50 Hz, single phase transformer gave the following test results: O.C Test (hv) : 2 kV, 1.75 kW, 1.8 A S.C Test (lv) : 13 V, 1 kW, 300 A (i) Calculate the parameters of equivalent circuit as referred to H.V side (ii) Determine voltage regulation and efficiency at full-load, 0.8 power factor lagging
- aWhat is V-V connection? Show that the open delta connection has a kVA rating of 57.7% of the rating of the normal delta-delta connection
- bExplain Sumpner’s test in transformer with neat diagram
Question text is extracted from the official AKTU question paper PDF above. Check the original PDF for equations, diagrams and complete wording. Extracted: 2026-08-23.
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