Analysis of Electrical Machines M.E Question Paper : jaduniv.edu.in

Name of the University : Jadavpur University
Department : M. Power Engg. Examination
Degree : M.E
Subject Name : Analysis Of Electrical Machines
Sem : I
Website : jaduniv.edu.in
Document Type : Model Question Paper

Download Model/Sample Question Paper : https://www.pdfquestion.in/uploads/dspace.jdvu.ac.in/6155-Analysis%20of%20Electrical%20Machines.pdf

Jadavpur Analysis of Electrical Machines Question Paper

M. Power Engg. Examination, 2008 :
(1st Semester)
Time : Three hours
Full Marks : 100
Use a separate Answer-Script for each part.

Related : Jadavpur University Steam & Gas Turbine M.E Question Paper : www.pdfquestion.in/6152.html

PART–I

(70 marks)
Answer any four questions. :
(2 marks for neatness)
1. Write the flux linkage and voltage equations of a Kron’s primitive machine and obtain its impedance matrix. Also obtain an expression for electrical torque of the Kron’s primitive machine. Show that no torque is produced by interaction between the flux and current on the same axis. 17

2. Derive the transformations for currents between a rotating balanced 2-phase (a , b) winding and a pseudo-stationary two phase (d, q) winding. Assume equal turns on all coils. Show that the transpose of current transformation matrix is equal to its inverse.
For steady state balanced operation with
ia = ImCos(wt + j)
and ib = ImSin(wt + j)
determine the primitive coil current id and iq, and show that these are steady dc values. 17

3. What are the various basic parameters of a synchronous machine ?
Derive expressions for armature mutual inductances of salient pole synchronous machine. Explain with diagrams. 17

4. Deduce Park’s transformations relating the three phase currents of a synchronous machine to is corresponding d–q axes currents and its inverse. What is meant by ‘power invariance’ ? If current connection matrix [ C ] is given, find the new voltage matrix and the transformed impedance matrix in case the currents are
(i) instantaneous, and
(ii) expressed in complex notation. 17

5. A symmetrical sudden 3-phase short circuit is applied to the terminals of an excited salient pole synchronous generator (without damper bars) running at synchronous speed and at no load. Develop an expression for the armature current in any instant of time following the short circuit, in case armature transformer voltages and armature resistances are neglected. 17

6. Develop a suitable model of a salient pole synchronous machine (without dampers) in d–q reference frame. Starting from the impedance matrix of the same, derive the phasor voltage equation under balanced steady state operation. Hence draw phasor diagrams for both motor and generator. 17

PART–II

(30 marks)
Answer any three questions. :
7. Incorporating the effect of saturation and considering a primitive physical Model, derive the expression for flux and voltages for the model. 10

8. Explain with diagram the universal field oriented current controller and explain the machine performance under constant air gap flux situation. 10
9. Find the expression of current in the event of a sudden short circuit for a 3 phase induction motor. Assume the reference frame is attached to the rotor and transient begin on no load. 10

10. Sketch and explain with block diagram the universal vector decoupling control of an Induction motor using Rotor Field oriented control ( I type). 10
11. Using space phasor equations find the transient and subtransient inductances of an induction motor. 10

Syllabus

PE/T/425B Advanced Topics In Electrical Machines Syllabus :
Generalized theory of electrical machines, linear transformations – matrix model of dc, inductive & synchronous machines – motional impedance matrix, effects of saturation, harmonics & solid iron rotor/pole shoe on the performance of synchronous machines, stability assessment in terms of generalized machine model, Asynchronous operation of synchronous machines – resynchronisation – self syncronisation, heating & cooling of large power transformers & turbine-generators, effects of surge voltage on electrical machines, industrial testing of electrical machines – types tests & routine tests – IS specifications.