Maharashtra State Board of Technical Education 2011-4th Sem Diploma Industrial Electronics for in EngineeringSubject :- power electronics(12121) - Question Paper
MSBTE ques. paper for Diploma in Industrial Electronics Engineering
Fourth Semester
Subject :- power electronics(12121)
21011
3 Hours/100 Marks
Scat No.
(1) All questions are compulsory.
Instructions :
(2) Answer each next main question on a new page.
(3) Illustrate your answers with neat sketches wherever necessary.
(4) Figures to the right indicate full marks.
(5) Mobile Phone, Pager and any other Electronic Communication devices are not permissible in Exwnination Hall.
Marks
1. Attempt any five of the following : 20
a) State the pulse characteristics required to trigger SCR successfully.
b) Draw symbol of SIJS, SBS, LASCR. DIAC.
c) Draw the circuit diagram of PUT relaxation oscillator.
d) Explain turn off mechanism of SCR.
e) State the need of series connection of SCR.
f) State two advantages of three phase rectifier over single phase rectifier.
g) Draw the symbol of Triac and explain working principle of triac.
a) Draw and describe static switch using SCR.
b) State and explain the use of free wheeling diode.
c) State the reasons of unequal distribution of current in parallel connection of SCR.
d) Draw class B commutation circuit. State condition of resonant circuit in it, give one application of it.
e) Explain light triggering method of thyristors.
f) State the needs of high power semiconductor switches.
a) In an application, SCR is triggered using pulse triggering method. The specifications of SCR used are turn on time = i (K) micro sec.
Vgmin = L5 V-
A pulse of amplitude 2v and pulse width 0.2 ms is used to trigger SCR state, whether SCR will trigger or not justify your answer.
b) Draw and explain class A commutation method of SCR.
c) Draw and explain static ac switch using inverse parallel SCR circuit.
4. Attempt any two :
Marks
16
12121
a) Draw and explain power flip-flop circuit using SCR. State advantage of it.
b) Differentiate between symmetrical and asymmetrical single phase half controlled bridge rectifier mid explain freewheeling action.
c) Explain operating principle of GTO mid draw constructional diagram of GTO. State the specification of GTO.
5. Attempt any four of the following : 16
a) Which junction is responsible for the conduction of LASER when light is incident on it ?
b) Draw the circuit diagram of IJJT relaxation oscillator mid write the expression for frequency.
c) Draw and explain class E commutation method. Name commutating components.
d) Draw and explain dynamic voltage equalization circuit (any one).
e) Define the following of a uncontrolled rectifier, i) Efficiency ii) PIV
iii) TUF iv) Form factor
0 Draw the circuit of single phase half wave controlled
i) Rectified with RL load
ii) Also, sketch the waveform for a = 45
iii) a) Load voltage waveform
b) Load current waveform.
6. Attempt any four : 16
a) Explain the advantages of gate triggering.
b) Draw mid explain AC to DC converter.
c) Draw the characteristics and explain working principle of PUT.
d) Draw the V-I characteristics of SCR. What is the effect of gate current on operation of SCR.
e) List the factors affecting operation of series combination of SCR.
f) Define following with respect to SCR
i) Holding current ii) Latching current.
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| Earning: Approval pending. |
