7/29/2019 BET Assignment 1 - 2013 Jan Batch

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Department of Electrical & Electronics Engineering

Manipal Institute of Technology, Manipal

Second Semester B. Tech.: JanMay 2013

BASIC ELECTRICAL TECHNOLOGY (ELE 102)

FIRST ASSIGNMENT

Last Date for Submission: 28 February 2013

1. Determine resistance between the terminals M and N of the network shown in fig. 12. Reduce the network shown in fig.2 to a single voltage source with its internal resistance using sourcetransformation across AB3. Using source transformation, determine power dissipated by 5.8 k resistor in fig. 34. The coil of relay takes a current of 0.12A when it is at the room temperature of 15 C and connected

across a 60V supply. If the minimum operating current of the relay is 0.1A, Calculate the temperature

above which the relay will fail to operate when connected to the same supply. Resistance-temperature

coefficient of the coil material is 0.0043/C at 0C

5. Use mesh analysis to find the power delivered by the 60V battery in fig. 4.6. For the circuit shown in figure 5, use node voltage analysis to determine Vx and Ix.7. Find the current I0, shown in fig. 6 using node voltage analysis.8. In fig. 7, determine the power dissipated by the 10 resistor. Also, find the current in 4. Solve using

node voltage analysis and verify by mesh analysis.

9. In the fig. 8, obtain the voltage V2 and V3 of the circuit10.For the circuit shown in fig. 9, the switch is initially closed at position 1. When the capacitor voltage

reaches a value of 25V, the Switch S is changed over to position 2

a. Find the equation of voltage across the capacitor after switching to position 2b. What is total time taken for the voltage to reach 10Vwhen switch is in position 2?

11.In the fig. 10, switch is closed at t = 0. Determine the expression for the current and find the current at t =5m second.

12.Two magnetically coupled coils, coil 1 and coil 2 having 200 turns and 1000 turns respectively, has acoupling co-efficient of 0.85. A current of 6.5A flows in coil 2 while keeping coil 1 open and produces a

flux of 0.71 mWb in it. Find the self-inductance of the 2 coils and the mutual inductance between them.

13.A magnetic circuit comprises four parts in series. They are,a. Length A of 50mm, cross sectional area 40mm2, r= 1000b. Length B of 100mm, cross sectional area 180mm2, r= 1400c. Length C of 180mm, cross sectional area 180mm2, r= 1100d. Length of air gap, 2mm, cross sectional area of 80mm2

Calculate, (i) Reluctances offered by A, B, C and air gap; (ii) Total reluctance

A coil of 1000 turns is wound on part A and the flux density in air gap is 2.5T. Calculate exciting currentrequired if, (a) There is no leakage flux (b) = 1.5

14.In the fig. 11, the coils are connected in series. Determine the equivalent inductance. Derive the formulaused.

15.In fig. 12, a magnetic circuit is made of silicon steel with a uniform cross section of 600mm 2. Length ofcentral limb BE is 200mm, length of BCD = length of BAFE = 450mm. Length of air gap PQ is 1mm and

RS is 3mm. The relative permittivity of core is 1400. Find the current required for the exciting coil to

produce a flux of 10mWb in the air gap of central limp. (Leakage factor = 1.2)

7/29/2019 BET Assignment 1 - 2013 Jan Batch

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N

5

5

10

025

158

20

30

5

6V

25V

2

3

365A

5A

10A

B

A

4mA3V0 k 10 k

9.7 k 5.8 k

3

5

4

6

5

10

55

10 10

6

+ Vx -

5A

60V

10Vx

Ix

2I

A

1A

5

8

55

10

3A

+ Vx -

3Ix

Ix

0Vx

10V

+-

12 V

3 k 4mA2 k1

2 k3 k

I0

2

1

8105

3

2

A

5A

12V

6V

+

-6

Vy+ Vy -

10 V

Iy

8

1

2

23

10 10

20 5 F0 V

12

10 0.1 H

100 V

. . .1mH

1mH

2mH 6mH4mH

1mH

Fig. 1Fig. 2

Fig. 3

Fig. 4

Fig. 5

Fig. 7

Fig. 8

Fig. 10

Fig. 11Fig. 12

Fig. 9