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Birla Institute of Technology & Science, Pilani

Work-Integrated Learning Programmes Division

First Semester 2010-2011

Mid-Semester Test

(EC-1 Make-up)

Course No. : ENGG ZC111

Course Title : ELECTRICAL & ELECTRONICS TECHNOLOGY

Nature of Exam : Closed Book

Weightage : 40%Duration : 2 Hours

Date of Exam : 10/10/2010 (AN)

Note:

1. Please follow all theInstructions to Candidates given on the cover page of the answer book.2. All parts of a question should be answered consecutively. Each answer should start from a fresh page.3. Mobile phones and computers of any kind should not be used inside the examination hall.

4. Use of any unfair means will result in severe disciplinary action.

Q.1. Find the currents through each resistor for the circuit shown in figure1: [5]

Fig1

Q.2. Two circuits, the impedances of which are given by Z1=10+j15 and Z2=6-j8

are connected in parallel. If the total current supplied is 15A. What is the power

taken in each branch? Find also the power factor of the individual circuit andcombination, Draw the phasor diagram. [7]

Q.3. Draw the response curves for current through inductor, iL(t) and voltage across

inductor, vL(t) for the series RL circuit shown in the figure2 where u(t) is a

mathematical function such that for t=0sec, u(t) = 1. [7]

ENGG ZC111 (EC-1 Make-up) First Semester 2010-2011 Page 1 of 9

No. of Pages = 2

No. of Questions = 6

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Fig2

ENGG ZC111 (EC-1 Make-up) First Semester 2010-2011 Page 2

Q.4. Define voltage regulation of a single phase transformer. The primary andsecondary windings of a 40KVA 6600/250V single phase transformer have

resistances of 10 and 0.02 respectively. The single leakage reactance in theprimary circuit (Xe) is 35 . Find voltage regulation at a power factor of load

equal to 0.8 lagging. [7]

Q.5. Find the Nortons equivalent of the circuit to the left of the terminals a and b for

the circuit shown in figure3. Use this result to find i. [7]

Fig3

Q.6. An inductor circuit draws 10A and 1KW from a 200V 50Hz supply. Determine

6.1. Impedance in Cartesian form

6.2. Impedance in Polar form

6.3. Power factor

6.4. Reactive power 6.5. The Apparent power

[7]

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