Insight of the paper:

The paper of Punjab Technical University on Magnetic circuits and Transformers (EE-203) basically include plenty of topics on electromagnetism. It follows the fundamental physics on electrostatics, magneto statics, electrodynamics, electrical network etc.

Examination:

Three sections are there in the paper in which questions from the first section is necessary to attend as there are no choices given in this section. But other section contains some alternates.

Pattern of the paper:

The paper on Magnetic circuits and Transformers is 3 hrs based with maximum 60 marks for the externals. And 40 marks are there on the basis of internal examinations. Three sections are there. First section is about short answer type questions. All the questions carry 2 marks each. The rest of the sections are descriptive type. In section B questions are allotted 5 marks each and 4 questions have to be attended. And for the last section, 10 marks is given to each question and one have to attend 2 questions. Some restrictions are given in the beginning of the paper and students are requires to follow the guidelines.

Recommended books:

Electric Machinery—-Fitzgerald, Kingsley & Kusko (Mcgraw Hill)

Performance design & Testing of A.C. Machines—- M.G. Say (CBS, Delhi)

Magnetic Circuits and Transformers—- MIT staff

Electrical Machines—- Nagrath & Kothari (TMH)

Theory of Alternating Current Machines—- A.S. Langsdorf(TMH)

Transformer Engineering—- L.F. Blume

Syllabus:

• ELECTROMAGNETISM:

Review of electromagnetism, Magnetic field strength, Magnetic force.

• MAGNETIC CIRCUITS:

Magneto motive force , reluctance, laws of magnetic circuits , determination of ampere-turns for series and parallel magnetic circuits , magnetic leakage and fringing, hysteresis and eddy current losses.

• ELECTROMAGNETIC INDUCTION:

Faraday’s laws, Lenz’s law, statically and dynamically induced E.M.F., Energy stored in magnetic field.

• TRANSFORMERS:

Introduction, Principle of working, construction of single phase transformer, EMF equation, phasor diagramon no-load, leakage reactance, transformer on load, equivalent circuit, voltage regulation, power and energyefficiency, open circuit and short circuit tests, equivalent circuit parameters estimation.Effect of saturation on exciting current, in-rush current phenomenon.Parallel operation of single phase transformer.

• AUTO TRANSFORMER:

Principle of operation, comparison with two winding transformers.

• THREE-PHASE TRANSFORMERS:

Different winding connections, Voltage and current ratios, comparative features, effect of connections on exciting current, Parallel operation. Three winding transformer-equivalent circuit, off-load and on-load tap changing transformer, Scott connections.