EE8301 Important Questions Electrical Machines 1

EE8301 Important Questions Electrical Machines 1 Regulation 2017 Anna University free download. Electrical Machines 1 Important Questions EE8301 pdf free download.

Sample EE8301 Important Questions Electrical Machines 1:

1. Mention the types of electrical machines.
There are three basic rotating machines types, namely
a. The dc machines
b. the poly phase synchronous machine (ac), and
c. Poly and single phase induction machine (ac)and a stationary machine,
namely Transformer EE8301 Important Questions Electrical Machines 1
2. State Ohm’s law for magnetic circuit.
It states that the magneto motive force across the magnetic element is equal to
the product of the magnetic flux through the magnetic element and the reluctance of
the magnetic material. It is given by
MMF = Flux X Reluctance
3. Define leakage flux
The flux setup in the air paths around the magnetic material is known as
leakage flux.
4. Define magnetic reluctance EE8301 Important Questions Electrical Machines 1
The opposition offered by the magnetic circuit for the magnetic flux path is
known as magnetic reluctance. It is analogous to electric resistance.
5. Draw the typical normal magnetization curve of ferromagnetic material.
6. What is fringing?
In the air gap the magnetic flux fringes out into neighboring air paths due to the
reluctance of air gap which causes a non uniform flux density in the air gap of a
machine. This effect is called fringing effect.
7. State stacking factor. EE8301 Important Questions Electrical Machines 1
The stacking factor is defined as the ratio of the net cross sectional area of a
magnetic core to the gross cross sectional area of the magnetic core. Due to lamination
net cross sectional are will be always less than gross cross sectional area. Therefore the
value of stacking factor is always less than unity.
8.Mention some magnetic materials
Alnicos, chromium steels, copper–nickel alloy, nickel, cobalt, tungsten and aluminium.
9. What is magnetostriction?
When ferromagnetic materials are subjected to magnetizing mmf, these may
undergo small changes in dimension; this phenomenon is known as magnetostriction.
10.Define statically induced emf.
The coil remains stationary with respect to flux, but the flux through it changes
with time. The emf induced is known as statically induced emf.
11. Define dynamically induced emf. EE8301 Important Questions Electrical Machines 1
Flux density distribution remains constant and stationary but the coil move relative
to it.The emf induced is known as dynamically induced emf.

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EE8391 Important 16 Mark Questions Electromagnetic Theory

EE8391 Important 16 Mark Questions Electromagnetic Theory Regulation 2017 Anna University free download. Electromagnetic Theory Important 16 Mark Questions EE8391 pdf free download.

Sample EE8391 Important 16 Mark Questions Electromagnetic Theory:

1. Write short notes on the following: (a) Gradient (b) Divergence (c)Curl (d) Stoke
theorem.
:
2. Express the vector B in Cartesian and cylindrical systems. Given,
Then find B at (-3, 4, 0) and (5, π/2 , -2)

3. i) Describe the classification of vector fields and a point Q is located at (-2 , 6,3), express (a) the point Q in cylindrical and spherical coordinates,(b) B in spherical coordinates. EE8391 Important 16 Mark Questions Electromagnetic Theory

4. Determine the divergence and curl of the following vector fields:
=ρ

5. i)Given point P( -2,6,3) and ,express P and in cylindrical
coordinates.
ii) state and prove divergence theorem. EE8391 Important 16 Mark Questions Electromagnetic Theory

6. i) Determine the curl of the following vector fields:
ii) Given that , evaluate both sides of Stoke’s theorem for a
rectangular path bounded by the lines x= ± a, y=0,z =b.

7. i) Find the electric field at a point P(0,0,6) due to a point charge Q1 of 0.35 μC placedat
(0,5,0) and Q2
ii) obtain in the spherical coordinate system the gradient of the function
of -0.6 μC placed at (5,0,0). EE8391 Important 16 Mark Questions Electromagnetic Theory
.
8. i) State and derive divergence theorem.
ii) show that in catesian coordinates for any vector A, .

9. Explain the different coordinate systems.

10. Write short notes on gradient,divergence, curl and stokes theorem.

1. Deduce an expression for the capacitance of parallel plate capacitor having two identical media. EE8391 Important 16 Mark Questions Electromagnetic Theory

2. i) state and derive electric boundary condition for a dielectric to dielectric medium and a conductor to dielectric medium.
ii)Derive the expression for energy density in electrostatic fields.

3. (i)State and explain coulomb’s law and deduce the vector form of force equation between two point charges.
(ii)At an interface separating dielectric 1(εr1) and dielectric 2(εr2) show that the tangential component of is continuous across the boundary, whereas the normal component of is discontinuous at the boundary. EE8391 Important 16 Mark Questions Electromagnetic Theory

4. (i) A circular disc of radius ‘a’ m is charged uniformly with a charge density of ρsC/m2

ii) find the value of capacitance of a capacitor consisting of two parallel metal plates of 30cm x 30cm surface area, separately by 5mm in air. What is the total energy stored by capacitor is charged to a potential difference of 1000v? what is the energy density?
.
Find the electric potential at a point P diatant ‘h’ m from the disc surface along its axis. EE8391 Important 16 Mark Questions Electromagnetic Theory

5. i)A circular disc of radius ‘a’ m is charged uniformly with a charge density
of’σ coulombs/m2
ii)Determine the electric field density at P(-0.2,0, -2.3) due to a point charge of +5nC at
Q(0.2, 0.1, -2.5) in air. All dimensions are in meter.
. Find the potential at a point ‘h’m from the disc surface along its axis.

6. Find the potential at any point along the axis of a uniformly charged disc of σ c/m2

7. Derive the expression for energy stored and energy density in electrostastic fields. The disc has radius of ‘a’ m EE8391 Important 16 Mark Questions Electromagnetic Theory

8. Derive the boundary conditions at the interface of two dielectrics.

9. Point charges 1 mC and -2 mC are located at (3,2,-1) and (-1, -1,4) respectively.
Calculate the electric force on a 10nC charge located at (0,3,1) and the electric field intensity at the point.

10. A linear ,homogeneous , isotropic dielectric material has εr=3.6 and is covering the space between z=0 and z=1. If v= -6000z volts in the material, find EE8391 Important 16 Mark Questions Electromagnetic Theory

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EE8391 Important Questions Electromagnetic Theory

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Sample EE8391 Important Questions Electromagnetic Theory:

1. Define current density.

Current density is defined as the current per unit area.
J= I/A Amp/m2

2. What is meant by displacement current?

Displacement current is nothing but the current flowing through capacitor. J= D / t

3.State point form of ohms law. EE8391 Important Questions Electromagnetic Theory

Point form of ohms law states that the field strength within a conductor is proportional to the current density.
J=σE

4. Define surface charge density.

It is defined as the charge per surface area.
ρS=Q/S

5.Define magnetic vector potential.

It is defined as that quantity whose curl gives the magnetic flux density.

6.Write down the expression for magnetic field at the centre of the circular coil.

I=Current
A=Area

7.Give the relation between magnetic flux density and magnetic field intensity. EE8391 Important Questions Electromagnetic Theory

B =μ H
Where, H=Magnetic Field Intensity
B=Magnetic Field Density

8.Write down the magnetic boundary conditions.

i) The normal components of flux density B is continuous across the
boundary.
ii) The tangential component of field intensity is continuous across the
boundary.

9. Give the force(F) on a current element (dl). EE8391 Important Questions Electromagnetic Theory

dF = BIdlsinθ
Where, B=Magnetic Field Density
I=Current

10.Define magnetic moment.

Magnetic moment(m) is defined as the maximum torque (T) per magnetic induction
of flux density (B).
m=T/B

11. State Gauss law for magnetic field. EE8391 Important Questions Electromagnetic Theory

The total magnetic flux passing through any closed surface is equal to zero.
B.ds =0 Where, B=Magnetic Field Density

12. Define magnetic field strength.

The magnetic field strength (H) is a vector having the same direction as
magnetic flux density (B). H=B/μ

13. Give the formula to find the force between two parallel current carrying
conductors.

F=μI1.I2 / 2ΠR
Where, F=Force I=Current
R=Distance between charge

14. Give the expression for torque experienced by a current carrying loop situated
in a magnetic field.

T = IABsinθ
Where, T=Torque
I=Current
A=Area
B=Magnetic Field Density EE8391 Important Questions Electromagnetic Theory

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EE8351 Important 16 mark Questions DIGITAL LOGIC CIRCUITS

EE8351 Important 16 mark Questions DIGITAL LOGIC CIRCUITS Regulation 2017 Anna University free download. DIGITAL LOGIC CIRCUITS Important 16 mark Questions EE8351 pdf free download.

Sample EE8351 Important 16 mark Questions DIGITAL LOGIC CIRCUITS:

1. Develop the state diagram and primitive flow table for a logic system that has two inputs S and R and a single output Q. The device is to be an edge triggered SR flip- flop but without a clock. The device changes state on the rising edges of the two inputs. Static input values are not to have any effect in changing the Q output (16) EE8351 Important 16 mark Questions Digital Logic Circuits

2. Design an asynchronous sequential circuit that has two inputs X2 and X1 and one output Z. The output is to remain a 0 as long as X1 is a 0. The first change in X2 that occurs while X1 is a 1 will cause a Z to be a 1. Z is to remain a 1 until X1 returns to 0. Construct a state diagram and flow table. Determine the output equations. (16) EE8351 Important 16 mark Questions Digital Logic Circuits

3. Construct the state diagram of a Mealey Pattern detector that can detect a serial string of 4 inputs,where each input is a four bit code. If the string of four bit codes is correctly
received,then an output is generated. An incorrect input code pattern is to generate a second output.The second output is to be asserted only after receiving the sequence of four bit codes.

4. Draw the state diagram and obtain the primitive flow table for a circuit with two inputs x1 and x2 and two outputs z1 and z2 that satisfies the following conditions. When x1 x2 = 00 output z1 z2 = 00, when x1= 1 and x2 changes from 0 to 1 the output z1 z2 = 01, when x2= 1 and x1 changes from 0 to 1 the output z1 z2 = 10 otherwise output does not change. (16) EE8351 Important 16 mark Questions Digital Logic Circuits

5. Design an asynchronous binary toggle circuit that changes state with each rising edge of clock input. Assume the initial output as zero. (16)

6. Write notes on the following giving one example for each. (8)
Stable state,Unstable state,Cycles,Race

7.Analyze the Boolean expression, K- Map, transition and state table and primitive flow table of the following asynchronous sequential circuits. EE8351 Important 16 mark Questions Digital Logic Circuits

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Sample EE8351 Important Questions DIGITAL LOGIC CIRCUITS:

1. Where the digital systems are used?

Digital systems are used extensively in computation and data processing, control systems, Communications and measurements. Since digital systems are capable of greater accuracy and reliability than analog systems, many tasks formerly done by analog are now being performed digitally.

2. What is the difference between analog and digital systems?

In a digital system the physical quantities or signals can assume only discrete values, while in analog systems the physical quantities or signals vary continuously over a specified range. EE8351 Important Questions Digital Logic Circuits

3. What is a binary number system and Why are binary numbers used in digital systems?

The number system with base (or radix) two is known as the binary number system. Only two symbols are used to represent the numbers in the system and these are 0 and 1.The outputs of the switching devices used in digital systems assume only two different values. Hence it is natural to use binary numbers internally in digital systems.

4. What is the difference between binary code and BCD?

Binary:

i. Any distinct element can be represented by a binary code.
ii. No limitation for the minimum or maximum number of elements required for coding the element. EE8351 Important Questions Digital Logic Circuits

BCD:

i. Only a decimal digit can be represented.
ii. It is a four bit representation.

6. What is a gray code and mention it‟s advantages.

A gray code is a non weighted code which has the property that the codes for successive decimal digits differ in exactly one bit.
The gray code is used in applications where the normal sequence of binary numbers may produce an error during the transition from one number to the next. EE8351 Important Questions Digital Logic Circuits

7. What is meant by non-weighted codes?

Each bit has no positional value i). Excess-3 code ii).Gray code iii).Five bit BCD

8. List the names of universal gates. Why it is named so?

NAND and NOR gates are universal gates. Because a combination of NAND gates or a combination of NOR gates can be used to perform functions of any of the basic logic gates EE8351 Important Questions Digital Logic Circuits

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EE8353 Important 16 mark Questions ELECTRICAL DRIVES AND CONTROLS

EE8353 Important 16 mark Questions ELECTRICAL DRIVES AND CONTROLS Regulation 2017 Anna University free download. ELECTRICAL DRIVES AND CONTROLS Important 16 mark Questions EE8353 pdf free download.

Sample EE8353 Important 16 mark Questions ELECTRICAL DRIVES AND CONTROLS:

1.Draw a neat schematic diagram of a three point starter and explain its working. (16)

2. Draw a neat schematic diagram of a four point starter and explain its working. (16) EE8353 Important 16 mark Questions Electrical Drives and Controls

3. Explain with neat circuit diagram, the star-delta starter method of starting squirrel cage induction motor. (16)

4. Explain the typical control circuits for DC Series and Shunt motors (16)

5. Explain the different starting methods of three phase squirrel cage induction motors with neat sketches. (16)

6. Explain different methods of starting of DC Motors. (16) EE8353 Important 16 mark Questions Electrical Drives and Controls

7. Explain with neat diagram the starting of three phase slip ring induction motor. (16)

8. Draw and explain the push-button operated direct-on line starter for three
phase induction motor. (16)

9. Draw and explain the manual auto-transformer starter for three phase induction motor. EE8353 Important 16 mark Questions Electrical Drives and Controls

10. (a). A starter required for a 220V shunt motor. The maximum allowable current is 55 A and
the minimum current is about 35 A .Find the number of starter resistance required and the
resistance of each section. The armature resistance of the motor is 0.4 ohm.(8)
(b). A three phase delta connected cage type induction motor when connected directly to 400
V, 50 HZ supply takes a starting current of 100 A in each stator phase. Calculate
(i).line current on direct on line starting.
(ii).line and phase starting currents for star-delta starting.
(iii).line and phase starting currents for a 70% tapping on autotransformer starting.(8)

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EE8353 Important Questions ELECTRICAL DRIVES AND CONTROLS

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Sample EE8353 Important Questions ELECTRICAL DRIVES AND CONTROLS:

1. Why a single phase induction motor does not self start?
When a single phase supply is fed to the single phase induction motor. Its stator
winding produces a flux which only alternates along one space axis. It is not a
synchronously revolving field, as in the case of a 2 or 3phase stator winding, fed from 2 or 3 phase supply.

2. Define Drive and Electric Drive.
Drive: A combination of prime mover, transmission equipment and mechanical working load is called a drive
Electric drive: An Electric Drive can be defined as an electromechanical device for converting electrical energy to mechanical energy to impart motion to different machines and mechanisms for various kinds of process control.

3. How heating occurs in motor drives?
The heating of motor due to losses occurring inside the motor while
converting the electrical power into mechanical power and these losses
occur in steel core, motor winding & bearing friction. EE8353 Important Questions Electrical Drives and Controls

4. Give some examples of Electric Drives.
Driving fans, ventilators, compressors and pumps.
Lifting goods by hoists and cranes.
Imparting motion to conveyors in factories, mines and
warehouses Running excavators & escalators, electric locomotives trains,
cars trolley buses, lifts & drum winders etc.

5. What is an individual electric drive? Give some examples.
In this drive, each individual machine is driven by a separate
motor. This motor also imparts motion to various other parts of the
machine. Single spindle drilling machine, Lathe machines etc. EE8353 Important Questions Electrical Drives and Controls

6. What is a multi motor electric drive? Give some examples.
In this drive, there are several drives, each of which serves to
activate on of the working parts of the driven mechanisms.

7. What are the classes of duties?
1. Continuous duty
2. Short time duty operation of motor Main classes of duties
3. Intermittent periodic duty
4. Intermittent periodic duty with starting
5. Intermittent periodic duty with starting & braking
6. Continuous duty with intermittent periodic loading
7. Continuous duty with starting & braking
8. Continuous duty with periodic load changes EE8353 Important Questions Electrical Drives and Controls

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