B.TECH - Semester 5 electrical technology Question Paper 2021 (dec)
Practice authentic previous year university questions for better exam preparation.
Sample Questions
- An § pole lap wound armature of a do machine has 960 conduclors, 32 mWb flux per pole and speed of 400 rpm , Calculate the emi generated on opon circuit. If the above armalure were wave connected, al what speed must it be driven to generale 400 V ?
- Whal do you mean by back eml in a DC molor? Whal is its significance?
- What are the applications of DC series motor? Explain why series molors are never slarted on No-load?
- Derive the ent equation of a single phase trans[ormer.
- Derive the condition for maximum efficiency of a Iransformer.
- Explain the operation of an induction molor. What is the relevance of slip?
- What is a universal molor? Mention any two applicalions.
- Compare the construction of synchromous generalor with thal of a DC generalor.
- Whal do you mean by synchronous condenser?
- What are the advanlages of electric braking? $$ (10 \times 4=40 \text { Marks }) $$ Answer any one full question from each modula.
- (a) What are the different types of DC generators? Explain with simple skelches. Also mention at leasl one application of each type.
- (b) What do you mean by armalure reaction in DC machines? Whal are its effects? Explain with neat figures.
- (a) A $250 \mathrm{~V}, 4$ pole wave wound do series motor has 782 conductors on its amalure. The folal ammalure resislance is $0.75 \Omega$. The molor lakes a current of 40 A . Estimate the speed and gross lorque if the flux per pole is 25 mW b.
- (b) What is the necessity of a slarler in a DC molor? Explain the operation of a 3-poinl starter with a neal figure. Module - 11
- (a) Explain with neat oircuil the OC and SC tesls on a transformer.
- (b) A 150 KVA transformer has an iron loss of 1400 W and full load copper foss of 1600 W . Find the efliciency at $50 \%$ load and upf.
- (c) Draw the vector diagram of a lransformer supplying lagging load.
- (a) Explain the operation of a three phase induction molor.
- (b) Derive the torque slip characleristics of a three phase induction molor.
- (c) Draw and explain the operation of a star-della starter.
- (a) Explain why a single phase induction molor is not self-slarling. Describe a melhod of starting.
- (b) Explain the working of a slepper moker. What are its applications?
- (c) Derive the emf equation of an alternator.
- (a) Explain why a synchronous molor is nol sell-slaring.
- (b) What do you mean by regulation of an allemator? Describe emf melhod of deriving the regulation.
- (c) With a functional schematic, describe an ac electric locomolive.