Assignment No. 3

Transcription

Assignment No. 3

Dayananda Sagar Academy of Technology and Management, Bangalore
Udayapura, Kanakapura Main Road, Bangalore-82
Department of Electrical and Electronics Engineering
ASSIGNMENT 3
POWER SYSTEM ANALYSIS
1. Explain types of unbalanced faults that occur in power systems.
(6marks)
2. Discuss briefly the open-conductor faults in power systems.
(June/July 2013,6marks)(may/june 2010,4marks)
3. Mention the boundary conditions for LL and LLG faults through fault impedance in a
power system.
(4 marks)
4. For the network shown in figure, determine the fault current for (i) 3 symmetrical fault
(ii) LG fault (iii) LL fault (iv) double line-to-ground fault.
Generator : 50 MVA,11 kv, Xd11 = 15%, X2 = Xd11; X0=8%.
Grounding Reactance = 2.5Ω
T1 and T2 : 11/132kv; 60MVA; X = 10%.
M1 : 30 MVA,11 kv, Xd11 = X2=20%; X0=8%.
M2 : 15 MVA,11 kv, Xd11 = X2=20%; X0=8%.
Grounding Reactance = 2.5Ω
Transmission line : X1 = X2; 120 Ω reactance; X0 = 3X1 .
Choose 11kv, 50MVA base in generator.
(December 2010, 20marks)
5. A 25MVA, 13.2 kv alternator , with a solidly grounded neutral has a subtransient
reactance of 0.25 pu. The negative and zero sequence reactances are 0.35 and 0.1 pu
respectively. Determine the fault current and the line-line voltage at the fault, when a
line-line fault occurs at the terminals of the alternator. Neglect the resistance.
(December 2011,12marks)
6. Determine the fault current for (i) 3 symmetrical fault (ii) LG fault (iii) LL fault (iv)
double line-to-ground fault.
20marks
7. A 30MVA, 13.8kv ,3- alternator has a subtransient of 15% and negative and zero
sequence reactance of 15% and 5% respectively. The alternator supplies two motors over
a transmission line having transformers at both ends as shown in figure. On the one line
diagram. The motors have rated inputs of 20 MVA and 10MVA. Both 12.5 kv with 20%
sub-transient reactance and negative and zero sequence reactions are 20% and 5%
respectively. Current limiting reactors of 2.0Ω each are in the neutral, of the alternator
and the larger motor. The 3- transformers are both rated 35MVA, 13.2 ∆-115 Y kv,
with leakage reactance of 10%. Series reactance of the line is 80Ω. The zero sequence
reactance of the line is 200Ω. Determine the fault current when (i) L-G fault (ii) L-L
fault and (iii) L-L-G fault takes place at point P. Assume Vf = 120 kv. Assume a base of
30MVA and base of 13.8kv in generator circuit.
(June/July 2009, 20marks)
8. A 25MVA , 11 kv , three phase generator has a subtransient reactance of 20%. The
generator supplied two motors over a transmission line with transformers at both ends as
shown in one line diagram in figure. The motors have rated inputs of 15 and 7.5 MVA,
both 10kv with 25% subtransient reactance. The 3 phase transformers are both rated
30MVA, 10.8/121 kv connection ∆ - Y with leakage reactance of 10% each. The series
reactance of the line is 10 ohms. Before the occurrence of a solid line to ground fault at
bus ‘g’, the motors are loaded to draw 15 and 7.5 MW at 10kv, 0.8 leading power factor.
If prefault current is neglected , calculate the fault current and subtransient current in all
parts of the system. Select the base of 25MVA and 11kv in generator circuit.
9. Define ‘FAULTS’ in power system, and how are the faults be classified and write them in
the order of their severity and which is the most frequency occurring fault.
(8marks)
10. Develop the positive and zero sequence network for the power system shown in figure.
Mark all the values in per unit on a base of 250MVA, 138 kv. The neutrals of all rotating
machines are connected to ground through a reactor of 5 based on their own rating.
The ratings of:
Generators (i) and (ii) : 20 MVA,13.2 kv, X1 = X2= 15%, X0 = 8%
Motor (iii): 30MVA, 6.9KV, X1 = X2= 20%, X0 = 8%
Transformers : Y-Y : 20MVA,138Y-138Y KV, X = 10%
Y-∆ : 15MVA,6.9∆-138Y KV, X = 10%
Transmission line (i) : X1 = 40Ω , X0 = 120Ω
Transmission line ii) and iii) : X1 = 20Ω , X0 = 60Ω
(June 2012,12 marks)
DAYANANDA SAGAR ACADEMY OF TECHNOLOGY AND MANAGEMENT
DEPARTMENT OF ELECTRICAL & ELECTRONICS ENGINEERING
ASSIGNMENT 3 : 2014-2015
Sub:Switchgear & Protection Subject Code: 10EE62 Teacher: R. Govindappa, SEM: VI
1. (a) What are the various abnormal running conditions that may occur in a generator? Explain them
briefly.
[05 M] June/July 2013,[10 M] June/July 2014.
(b). A 50 MVA, 3-PHASE, 33kV alternator is being protected by the use of current balance system using
2000/5 ampere current transformer. The neutral of the generator is earthed through a resistance of 7.5
ohms. If the minimum operating current for the relay is 0.5ampere, determine what percentage of
winding of each phase is unprotected against earth when the machine operating at normal voltage.
[05 M] June/July 2013
2). Draw and explain the Merz-price protection of alternator start windings, state its advantages (star &
delta connected alternators).
[10 M] December 2012
[10M] December 2011
[10 M] Dec.09/ Jan.10
3). A generator is provided with restricted earth fault protection. The ratings are 11kV, 5000kVA. The
percentage of winding protected against phase to ground fault is 80%. The relay setting is such that it
trips for 25% out of balance. Calculate the resistance to be added in neutral to ground connection.
[10M] December 2011
4). Describe the loss of excitation protection in a generator and its characteristics.[10 M] May/June 2010
5). Describe the Negative phase protection in a generator and its characteristics. [10 M] May/June 2010
6). Explain with neat sketches of two different methods of generator rotor earth fault protections. [10 M]
7). What are the different types, so faults that may occur in transformers in service? Explain them briefly.
8). Draw and explain Merz-price protection scheme for i) star - delta transformer
transformer.
ii) star - star power
[10 M] June 2012
9). With the basic circuit diagram, explain the harmonic restraint relay protection, for a transformer.
[10M] December 2011,[10 M] June/July 2014.
10). With the aid of neat circuit diagram, explain how protection for induction motor is given by, i) Single
phase preventer ii) Ground fault protection.
[10 M]
Dec.09/ Jan.10
11). A 3-phase, 220/11,000V transformer is connected in star-delta. The protective transformers on the 220V
sides have a current ratio of 600/ (5/
shall they be?
). What must be the ratio of the CT’s on the 11kV side and how
[10M] December 2011
12). A 3-phase transformer rated for 33kV/6.6kV is connected star/delta and the protecting current
transformers on the low voltage side have a ratio of 400/5. Determine the ratio of the current transformer
on HV side. Draw the connection diagram showing how the relay operates under fault conditions.
Assignment : III (2015)
Sub :
Electrical Machine Design (10EE63)
Sem : 6th
1. With usual notation, derive the output equation of a three phase induction motor. (jan-10,
july-11, july-13, jun-10 10M),
2. Find the main dimension, number of stator turns, size of conductor and number of slots of a
5HP, 400V, 3-phase, 50Hz, 4 pole, squirrel cage induction motor using delta starter. Assume
the following data: Average flux density in air gap = 0.46T, amp.Conductor/m at armature
periphery = 22 x 103, full load efficiency = 83%, full load p.f = 0.84(lag), winding factor =
0.955. Current density = 4 A/mm2, number of slots/pole/phase = 3, take L/T = 1.5. (june-13,
10M)
3. State the factors affecting , length of air gap in case of a 3 induction motor.
(Dec.2014/Jan.2015-5M)
4. Estimate the stator core dimension, number of stator slots and number of stator
conductor/slot for a 100KW, 3300V, 50Hz, 12-pole star connected slip ring induction motor.
Take the average gap
Density of 0.4wb/m2, ac/m= 25000, efficiency = 90%, p.f = 0.9 and winding factor = 0.96.
Choose the main dimension to give best p.f the slot loading must not exceed 500ac. (jun-12,
10M).
5. Briefly give the design procedure of stator teeth and stator core of a 3 induction motor.
(Dec.2014/Jan.2015-5M)
6. Determine the main dimensions, turns/phase, number of slots, conductor cross-section and
slot area of a 250HD, 3 , 50Hz, 400V,1410rpm, slip ring induction motor. Assume:
i)Barc = 0.5 wb/m2
ii)Ac/meter = 30000 A/m
iii)efficiency = 0.9
iv)power factor = 0.9
v)winding factor = 0.955
vi)current density = 3.5A/mm2
vii)slot space factor = 0.4
viii)(cre-length/pole pitch)=1.2
Assume machine delta connected (Dec.2014/Jan.2015-10M)
7. Determine the main dimensions, number of radial ventilation ducts, number of stator slots
and the number of turns/phase of a 3.7KW, 400V, 3-phase, 4-pole, and 50Hz squirrel cage
induction motor to be started by a star-delta starter. Workout the winding details. Take
average flux density in the gap = 0.45wb/m2, ampere conductor/meter is 23000, efficiency =
0.85, p.f = 0.84, winding factor = 0.955, stacking factor = 0.9, L/ = 1.5. (july-11, jun-10,
10M)
8. A 15KW, 3-phase, 6-pole, 50Hz, cage induction motor has following data; D = 0.32m, L=
0.125m, number of stator slots = 54, number of conductors per slot = 24, current in each
conductor is 17.5A, full – load power factor is 0.85 lagging. Design suitable cage rotor
giving number of rotor slots, section of each bar, and section of each end ring. Also calculate
the effective resistance of the rotor. The full-load speed is about 950rpm, resistivity of the
copper is 0.02ohm-mm2/m. (jun-10, jun-12, 10M
9. Discuss in detail , the criteria to be considered for determining the number of rotor slot of a
cage induction motor. (Ma/ June 2010, 10M)
10. A 15KW, 400V, 3-phase, 50Hz, 6-pole induction motor has a diameter of 30cms and length
of the core is 12cm. the number of stator slot = 72 with conductors per slot = 20. The stator is
delta connected calculate the magnetizing current per phase if the length of the airgap is
0.55mm. the gap contraction factor is 1.2, the mmf for iron parts is 30% that for air gap. Coil
span = 11slots, find the no load current and the power factor if the windage and friction
losses are 250watt and iron losses are 850watts. Winding phase spread = 600. (jan-13, 12M)
11. Discuss in detail the calculation of no load current of a 3-phase induction motor. (july-11,
dec-10, jun-10, 5M, 10M)
12. Find the magnetizing current, no load current and no load power factor of a 15HP, 440V, 6pole delta connected slip ring induction motor having the following data: number of stator
slots = 54, conductor/slot = 28, flux/pole = 8.25mWb, gap area/pole = 183.5cm2, gap length
= 0.55mm, iron losses = 510W, friction and windage losses = 110W, gap expansion coefficient = 1.33. Iron parts of magnetic circuit requires 20% of ATs required for the gap, KW
= 0.96. (july-13, 10M)
Dayananda Sagar Academy of Technology and Management
Department of Electrical & Electronics Engineering
ASSIGNMENT FOR THIRD TEST: 2014-15
Subject: Digital Signal Processing
Subject code: 10EE64
Class: VI SEM B.E
Date: 4-05-2015
UNIT- 7 & 8
1. Design
a
low
pass
FIR
filter
with
desired
frequency
response
e  j 2 w w   / 4 


Hd ( w)  

. Use rectangular window with N=5. (June-July
0
 w 

4


2009) (10 M).
2. The
frequency
response
of
an
FIR
filter
is
given
by
H (w)  e  j 3w 1  1.8 cos 3w  1.2 cos 2w  0.5 cos w.
Determine
the
coefficients of the impulse response h(n) of the FIR filter. (June-July 2009) (10 M).
3. The
desired
frequency
response
of
a
low
pass

e  j 3w

0
filter Hd ( w)  
0  w  / 2 

 . Design the filter for N=7, using
 / 2  w   
frequency sampling technique. (June-July 2009) (10M).
4. A low pass FIR filter is to be designed with the following desired frequency
transformation
methods.
Determine the filter co-efficient
1,
w(n)  
0,
5.
6.
7.
8.
9.
H d (e
jw

e  j 2 w
)

0
  / 4  w   / 4

.

 / 4  w

hd(n) if the window function is defined as
0n4 
jw
 Also, determine the frequency response H(e ) of the
otherwise 
designed filter. (Jan-2010) (10 M). (Dec 2011) (10 M) (Jan-2013) (10 M)
Compare IIR and FIR filters. (Jan-2010) (6 M). (July-2011) (6 M) (Jan-2013) (6 M)
The frequency response of a filter is described by : H(w) = jw – ≤ w ≤ Design the
filter using a rectangular window. Take N=7. (Jun-2010) (6M) (July-2014) (6 M)
Design a low pass digital filter to be used in an A/D-H(Z)-D/A structure that will have
a -3dB cutoff at 30 rad/sec and an attenuation of 50 db at 45 rad/sec. The filter is
required to have a linear phase and the sampling rate is 100 samples/sec. (Jun-2010)
(10 M)
What are the advantages and disadvantages with the design of FIR filters using
window function? (July-2014) (4M)
Deduce the equation for the frequency spectrum for the rectangular window defined
by,
0; otherwise
What is the width of main lobe of the spectrum? (July-2014) (6 M)
10. Explain why windows are necessary in FIR filter design. What are the different
windows in practice? Explain the design procedure for the design of FIR filters using
windows. (Dec-2010) (10M) (Dec-2013) (10 M)
11. Design an FIR (low-pass) filter using rectangular window with passband gain of 0 dB,
cut-off frequency of 200 Hz, sampling frequency of 1 KHz. Assume the length of the
pulse response as 7. (Dec-2010) (8 M)
12. Distinguish between the analog and digital filters. (Dec-2010) (8 M)
13. The
desired
response
of
a
low
pass
filter Hd (e
jw


e  j 3w ,  3 / 4  w  3 / 4
jw
)
 . Determine H(e ) for M=7,


3 / 4  w  

0,
using a Hamming window. (July-2011) (12M) (Dec 2011) (10 M) (Dec 2013) (12 M)
14. Design an FIR digital filter to approximate an ideal low pass filter with passband gain
of unity, cut-off frequency of 850 Hz and working at a sampling frequency of fs =
5000 Hz. Use a rectangular window. The length of the impulse response should be =
5. (July-2011) (8M)
15. Design a normalized linear phase FIR filter having the phase delay of T = 4 and al
least 40 dB attenuation in the stopband. Also obtain the magnitude frequency
response of the filter. (June-2012) (10 M) (Dec 2014) (10 M)
16. Explain the design of an FIR filter based on frequency sampling approach. (June2012) (10 M) (Dec 2014) (10 M)
17. Explain the design procedure for the design of FIR filters using windows
concept.(Jan-2013) (12 M)

18. Given H d e
 jw

 jwT

e


0;
for
 wc  w  wr
Find H(ejw) and obtain
otherwise
hd(n) of FIR filter for M = 7 and wc = 1 rad/sample of symmetric filter using
rectangular window. (July-2013) (14 M)
19. Realize FIR filter for given h(n) using frequency sampling technique h(n) = {1, 1, 0.5,
1, 1}.(July-2013) (10 M)
20. Determine the unit sample response of the ideal low pass filter. Can it be physically
implemented? Can it exhibit linear phase? Can it be stable? (July-2013, 2010
scheme) (8 M)
21. An FIR filter has the impulse response h(n) = (1, 2, 1). Design the corresponding
digital filter by the frequency sampling technique. (July-2013, 2010 scheme) (4 M)
22. A FIR filter is given by, y(n) = x(n)+2/5x(n-1)+3/4x(n-2)+1/3x(n-3). Draw the ladder
structure. (July-2014) (10 M)
23. Draw the direct form I and II realizations of a system with transfer function.
H Z  
0.28 z 2  0.319 z  0.04
0.5Z 3  0.3Z 2  0.17 Z  0.2 (June-July 2009) (6 M) (July-2011)
24. Obtain the cascade and parallel realizations for the system function given by
1 1
Z
4
H (Z ) 
 1 1  1 1 1 2 
1  Z 1  Z  Z 
4
 2
 2
 (June-July 2009) (14 M), (Jan1
2010) (14 M). (Dec-2013) (6 M)
25. Realize a linear phase FIR filter having the following impulse response.
1
1
1
1
h(n)   (n)   (n  1)   (n  2)   (n  3)   (n  4)   (n  5).
2
4
4
2
(Jan-2010) (6 M), (Jun-2010) (8 M) (July-2011) (6 M) (July-2013, 2010 scheme) (4
M)
1
1  Z 1
5
26. Consider H ( Z ) 
1
1
1 1 

1
 2 
 1  Z  Z  1  Z 
2
3
4



Realize the system in direct form I.
Realize the system in cascade form using the first order and second order form II
structures.
Realize the system in parallel form using the first order and second order form II
structures. (Jun-2010) (12 M)
27. Obtain the direct form-I, direct form-II, cascade and parallel form realizations for the
following system:
y[n]  0.75 y[n  1]  0.125 y[n  2]  6 x[n]  7 x[n  1]  x[n  2] (Dec2010) (14 M) (Dec-2013) (8 M) (Dec-2014) (14 M)
28. Describe with necessary diagram and equations, the linear phase structure of FIR
filter for even order. (Dec-2010) (6 M)
29. Find the parallel realization of the system
1 1
Z
4
H (Z ) 
 1 1  1 1 1 2 
1  Z 1  Z  Z 
2
4
 2

 (July-2011) (8 M)
1
30. Realize a linear phase FIR filter having the following impulse response.
1
1
1
h(n)   (n)   (n  1)   (n  2)   (n  3)   (n  4).
4
8
4
(Dec 2011) (6
M)
31. Draw the direct form-I and direct form – II , cascade and parallelrealizations for a
digital IIR filter described by the system function (Dec
8 z 3  4 z 2  11z  2
H  z 
1  2
1

 z   z  z  
4 
2  ) (6 M) (Jan-2013) (6 M)

2011
32. Obtain the parallel realization for the system function
H  z 
1  z 1 1  2z 1 
 1 1  1 1  1 1 
1  z 1  z 1  z 
2

 4
 8
 (Dec 2011) (8 M)
33. Determine direct forms I and II for the second order filter given by: Y(n) = 2 b cosw0
y(n-1) – b2 y(n-2) + x(n) – b cos w0 x(n-1). (June-2012) (8 M)
H  z 
2  8 z 1  6 z 2
1
1  8 z  12 z
34. Given the system function:
structure. (June-2012) (6 M)
35. Obtain cascade realization of the system function:
2
Realize using ladder
1 1
z  z 2
2
H Z  
1
1  z 1  z 2
4
(June-2012) (6 M)
z  1z  1z  2z
H  z 
1
1 
1
1 
1 
1

 z   j  z   j  z  j  z  j 
2
2 
2
2 
4 
4  in parallel

36. Realize
1
form. (Jan-2013) (8 M)
37. A discrete time system H(z) is expressed as,


 1
 2

101  z 1 1  z 1  1  2 z 1
 2
 3

H ( z) 
1  1   1
1  1 
 3 1  1 1   1
1  z 1  z 1    j  z 1    j  z 
2
2
 4
 8
  2
  2

Realize parallel and cascade forms using second order sections. (July-2013) (14 M)
(July-2014) (10 M)
38. Realize the following system function by linear phase FIR structure.
H(Z) = 1+1/2Z-1+1/3Z-2+1/7Z-3+1/3Z-4+1/2Z-5+Z-6 (Dec-2013) (6 M)
ASSIGNMENT 3
Sub : Embedded Systems
Subject code: 10EE665
Sem : VI
Teacher: Ramya S Rajan
1. What is switch bounce? Discuss how a capacitor eliminates switch bounce when pressed and when released
[12M] Jan13
2. List the important signals of RS232 communication cable. What are its limitations?
[8M] Jun 12
3. Define i) Frame ii) Simplex communication iii) Baud rate iv) bandwidth for serial communication with
respect to serial I/O, with examples
[10M] Jan13
4. Differentiate between
i) Half Duplex and full duplex communication
ii) Synchronous and asynchronous communication
[8M] Dec09/Jan10
5. With neat figures, explain three ways of interfacing multiple keys to a single 8-bit parallel port.
[10M] may/june10, Jan13, June12
6. Draw the neat diagram and explain the interfacing of seven segments LED
[12M] Dec10
7. With neat figures, explain memory mapped I/O and isolated I/O types of computer architectures.
[10M] Jan13
8. Design a circuit to interface a 4x4 matrix keyboard to the processor 68HC11. Explain the software
method implement key bounce.
[10M] Dec10, May/June06, Dec06/Jan07
9. Design a circuit to interface a simple LCD with MC14543
[8M] Dec11
10. Discuss briefly about interfacing EM relays, Solenoids and DC Motors
[10M] Jun 12
11. Draw the neat diagram and explain the interfacing external RAM with 68HC11 in expanded mode.
[10M] Dec10, Jan07
12. Explain the general approach to interfacing a memory to 68HC11 microcontroller in the expanded
mode.
[6M] may/june10, June12
13. Interface 8k x 8 static RAM to 6811 microcontroller. Draw read and write timing diagrams.
[12M]Dec09/Jan10

Assignment No. 3

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