2nd Sem DIP Electrical Circuits - May 2010.pdf

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SECTION - I(a) Fill in the blanks :

(i) Unit of mutual inductance is _.(ii) Instantaneous value of voltage is given by the equation(iii) Current behind voltage by 90' in h pure inductance.(iv) Line current is equal to in 3-phase star connected

system.(v) For transmitting

material requiredsystem.

O) State and explain reciprocity theory.

SECTION _ II(a) Define the following :

(i) Active circuits(iD Passive circuits

(b) Explain the meaning of closed circuit and(c) Using star-delta transformation. Find the. below.

Code : 9EE-23

1x5:5

II Semester Diploma Examination, May 2010

ELECTRICAL & ELECTRONICS ENGINEERING BOARI)

ELECTRICAL CIRCUITS

Time:3 Hours I

Instructions: (1) Section -Iis compulsory.

I Max. Marks : 100

@ Answer any two full questions from each of the remaining Sections - tr, m &rv.

1.

sameis

amount of power, thein case of

amount of conductor3-phase than l-phase

42.

short circuit.total current for the circuit shown

[Turn over

10v

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3. (a)

(b)

State and explaip super position theory.

Verify super position theory for the NW shown below.

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t0v

(c) State Thevenin's Theory.

(a) Define the following and mention their unit :

(i) Magnetic flux(ii) Flux density

(b) State and explain Lenz's law.

(c) A wire of 1 meter length moves at right angle to its lcng& at 60 m/sec in auniform magnetic field of density 1 wb/m2. Calculde tre €mf induced in aconductor when the direction of motion(i) peryendieular to the field(ii) parallel to the field(iii) inclined at 30o to the direction of.the field-

SECTION - IIIState and explain Fleming's Right Hand Rule. :

Compare self induced EMF with mutually inducedEMF.

B,'when carryinga certain current, if the current is reversed in 02 sec wtiat is the averagevalue of EMF induced in a coil.

4.

I

II

i

:,,

5. (a)

o)(c)

6. (a) Define:(i) Self tnductance

(ii) Mutual lnductance

O) Derive an expression for the energy stored in a magnetic field.

(c) An iron cored electromagnet; has a length of 100 cm and a diameter of 4 cm.Calculate its inductance, if the coil has 2000 furni and also calculate theenergy stored, when the current rises from 0 to 10 A. Take F.:500 for iron.

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I

9EE-23

7. (a)

(c)

(b)

3

Draw sine wave and mark the following :

(i) Maximum value(ii) fve and -ve cycle(iii) Time period

Define the following :

(i) Phase

(ii) Phase Difference

A sinusoidal alternating current is represented by i:0.707 sin 520 t.Find (i) Max. value

(ii) Current when t : 0.002direction.

(iii) RMS value of current.

sec passing through zero in positive

8.

SECTION _ IV(a) Define the following :

(i) Resonant frequency(ii) Quality factor

(b) Perform the following operation :

IfA:10+j6B:30 + j 52

Find (i) A x B (ii) #in polar forms.

(c) An inductive coil takes a current of 33.24 Athe resistance of the coil is 6 C), calculate thepower taken by the coil.

from 230 V, 50 Hz supply, ifinductance of the coil and the

4

e. (a)

(b)

(c)

10. (a)

(b)

(c)

Define phase sequence.

Derive the relationship between voltage and current in store connection.Three 100 p resistors are connected in star across 415 volts, 50H2,3-phasesupply. calculate the line and phase current and the power consumed.

what are the advantages of 3-phase system over l-phase system ?Derive an equation for 3-phase power.

Each of the two wattmeter connected to measure the input to a 3-phasecircuit reads 20 kw. what does each instrument reads, when the p.f. is b.aooleggng with the total 3-phase power remaining unchangeo in the alteredcondition.

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2nd Sem DIP Electrical Circuits - May 2010.pdf

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