BME703 Power & Control System B.Tech Question Paper : wbut.ac.in
Name of the University : West Bengal University of Technology
Department : Biomedical Engineering
Degree : B.Tech
Sem : VII
Subject Code/Name : BME-703/Power And Control System
Website : wbut.ac.in
Document Type : Previous Year Examination Question Paper
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Power & Control System Question Paper :
CS/B.Tech (BME)/SEM-7/BME-703/2009-10 :
Time Allotted : 3 Hours
Full Marks : 70
** The figures in the margin indicate full marks.
** Candidates are required to give their answers in their own words as far as practicable.
Related : West Bengal University of Technology BME704A Lasers & Fibre Optics in Medicine B.Tech Question Paper : www.pdfquestion.in/6671.html
GROUP – A : ( Multiple Choice Type Questions )
1. Choose the correct alternatives for the following : 10 × 1 = 10
i) The transfer function is defined for
a) linear and time variant system
b) linear and time invariant system
c) non-linear and time variant system
d) non-linear and time invariant system.
ii) An error detector is a control system that
a) detects one error and signals out an alarm
b) detects the error of the system only
c) pro duces an error signal of difference between theactual output and the desired value of the output
d) none of these.
iii) In Thyristor ( SCR ) permanent damage can arise due to high
a) di/dt b) dv/dt
c) none of these d) all of these.
iv) A power chopper converts
a) AC to DC b) DC to DC
c) DC to AC d) AC to AC.
v) Cycloconverter is a device that converts
a) AC to DC b) DC to AC
c) AC to AC d) none of these.
vi) In Thyristor anode current is made up from
a) electrons only
b) electrons and holes
c) holes only
d) none of these.
vii) A system will show undamped output when
a) ? = 0 b) ? > – 1
c) 0 < ? < 1 d) ? > 1.
viii) A phase controlled converter supplies a highly inductive load. It behaves as naturally commutated inverter when firing angle ( a ) is
a) a > 90° b) a < 90°
c) a = 90° d) a = 45°.
ix) A single phase full converter with free wheeling diode, supplies a high inductive load. The free wheeling diode conducts for ( assuming continuous load current )
a) a b) p – a
c) ß d) p + a.
GROUP – B : ( Short Answer Type Questions )
Answer any three of the following. 3 × 5 = 15
2. What are the main functions of a freewheeling diode ?
3. What is inverter ? Write down the classification of different types of inverters.
4. Find the overall T.F. using Manson’s gain formula for the signal flow graph shown below
5. Find the time response of 1st order control system subjected to unit ramp input function.
6. The characteristic equation for certain feedback control system is given below. Determine the range of values of K ( K > 0 ) for which the system is stable. S4 + S3 + S2 + S + K = 0.
7. a) What are the conditions for successful switching ( turnon ) of an SCR ?
b) What is the turn-off time of thyristors ? 3 + 2
GROUP – C : ( Long Answer Type Questions )
Answer any three of the following. 3 × 15 = 45
8. Sketch the nature of root locus of the system with loop transfer function
G (s) H (s) =
k ( s + 2 )
s ( s + 5 ) ( s + 7 )
as k varied from zero to infinity.
9. a) Define the terms ‘gain margin’ & ‘phase margin’.
b) A unit feedback control system has open loop transfer function
G (s) = 200 ( s + 5 )
s ( s + 5 ) ( s + 20 )
Sketch the Bode plot & show gain margin, phase margin, gain crossover frequency & phase crossover frequency. 4 + 7 + 4
10. a) Find the system equation of the mechanical system shown below. Also find the force-voltage ( f-v ) and forcecurrent
b) Find the overall transfer function shown below using block diagram reduction technique. 10 + 5.
Power & Control System – 2012
Time Allotted : 3 Hours
Full Marks : 70
** The figures in the margin indicate full marks.
** Candidates are required to give their answers in their own words as far as practicable.
GROUP – A : ( Multiple Choice Type Questions )
1. Choose the correct alternatives for any ten of the following : 10 × 1 = 10
i) The characteristics equation of a closed loop second order system is given as s2 + 4s +16 = 0 the resonant frequency in radian/sec of the system is
a) 2 b) 2 3
c) 4 d) 2 2 .
ii The number of roots lying on the right hand side of s-plane is
a) 1 b) 2
c) 3 d) 4.
iv) The signal flow graph of a system is shown in the figure below. The number of forward path is
a) 2 b) 3
c) 4 d) 5.
v) For a unit step input, a system with forward path transfer function G ( s ) = 20/s2 and feedback transfer function H (s ) = (s + 5 ) has a steady state output of
a) 0 b) 5
c) 0·2 d) 10.
vi) When the gain K of a system becomes zero, the roots of the loci
a) move away from the poles
b) move away from the zeros
c) coincide with the poles
d) coincide with the zeros.
vii) When cathode is more positive with respect to anode for a thyristor, the number of blocked PN junction is
a) 1 b) 2
c) 3 d) 4.
viii) A thyristor may be termed as
a) DC switch b) AC switch
c) either (a) or (b) d) square wave switch.
x) Most suitable solid state devices for audio, VHF/UHF and microwave amplifiers is
a) IGBT b) S.I.T.
c) MOSFET d) P.U.T.
xi) For a continuous conduction freewheeling diode conducts in a single semi converter for
a) a b) ß – ?
c) a + ? d) ß .
xii) For a continuous conduction in a single phase semi converter each SCR conducts for
a) a
b) a + 1
c) a + ?
d) a – ? .
xiii) In a single phase full converter, if output voltage has peak and average value of 325V and 133V respectively, then the firing angle is
a) 40° b) 140°
c) 50° d) 130°.
xiv) Each diode of a 3-phase half wave diode rectifier
conducts for
a) 60° b) 120°
c) 180° d) 90°.
xv) In a single phase full converter, the number of SCRs conducting during overlap is
a) 1 b) 2
c) 3 d) 4.
GROUP – B : ( Short Answer Type Questions )
Answer any three of the following. 3 × 5 = 15
2. Write short note on any one of the following :
i) Tachogenerator
ii) Error detector
iii) Synchro.
3. Find the overall transfer function of the system shown below : Use block diagram reduction method.
4. State Nyquist stability criterion & define gain margin, phase margin from the nyquist plot.
5. Draw the Static characteristics of a SCR, along with proper labelling. Also explain the different operating regions.
6. What are the applications of rectifier ?
7. Explain the function of a step down chopper.