৩৫তম বিসিএস ইইই লিখিত প্রশ্ন
আরমানি
বিষয় কোড : ৮৯১
নির্ধারিত সময়-৪ ঘন্টা
পূর্ণমান-২০০
দ্রষ্টব্য :—বাংলা অথবা ইংরেজি যে কোনো একটি ভাষায় উত্তর দিতে পারবেন, তবে
একই বিষয়ে বাংলা এবং ইংরেজি দুটি ভাষায় উত্তর দিতে পারবেন না। টেকনিক্যাল
শব্দগুলি ইংরেজিতে লিখতে পারবেন। প্রত্যেক প্রশ্নের মান প্রশ্নের শেষ
প্রান্তে দেখানো হয়েছে।
পার্ট-১
(১নং প্রশ্নসহ যে কোনো ছয়টি প্রশ্নের উত্তর দিতে হবে)
১. (a) Draw the connection diagram for measuring 3-φ power using two
wattmeter. [ ৫ ]
(b) With a diagram explain how MOSFET works as switch. [ ৫ ]
(c) If P1 and P2 be the iron and copper losses respectively of a
transformer on full load. Find ratio of P1 and P2 such that maximum
efficiency occurs at 75% of full-load. [ ৫ ]
(d) IGBT is a voltage controlled device. Why? [ ৫ ]
3. (a) Describe how the equivalent circuit of a single phase transformer
can be found from the following tests :--
(i) DC resistance test;
(ii) Voltage ratio test;
(iii) No load test;
(iv) Short circuit test.
(b) (i) Is it possible to operate an induction motor as asynchronous
generator? Why?
(ii) Draw torque-speed diagram of a 3-φ induction machine.
6. (a) What is 3 dB?
(b) How will a converter be converted into an inverter?
(c) How can a Thyristor turn off?
(d) Write down the expression for average voltage output for step down and
step up chopper.
7. (a) Why does the capacitor work on AC only?
(b) What is the phase voltage ratio between star and delta
circuit?
(c) Define commutation angle.
(d) How does an AC generator control VAR, voltage and power?
8. Write short notes on any four of the following :-
(a) NMOS and PMOS;
(b) Exclusive-OR gate;
(c) Faraday’s law of electromagnetic induction;
(d) Slip;
(e) Power factor.
পার্ট-২
9. (a) Why ac to dc and dc to ac conversion is taken place for
transmission of power import from other country?
(b) Explain standing wave generation in power transmission.
(c) Show the relation between ‘data’ and ‘channel capacity’.
(d) Draw the cluster of reuse factor of 7.
10. (a) Describe an HF6 circuit breaker with neat diagram.
(b) Draw a block diagram of a combined cycle gas based power plant and
explain its working principle.
11. (a) Suppose a mobile unit transmits 10 watt power. Express this power
in terms of dBm.
(b) Draw the PSK a wave form for the following data : 10100110.
12. (a) Expected life of a power plant is 25 years. Find the depreciation
rate, if the investment cost is 8%.
(b) If the reactance in Ohm is 20 Ohm, find the P.U. value for a base of
15 KVA and 10 KV.
13. (a) Mention the SNR importance in telecommunication
engineering.
(b) Digital signal requires much more bandwidth than original analog
signal. Why?
(c) Explain the effect of frequency on cell coverage.
(d) The wavelength range in optical communication is in between 1300
nm—1550nm. Why?
15. (a) Define attenuation.
(b) What are the shapes related to a cell?
(c) Draw the diagram of multiplexing.
(d) In what way CDMA differs from FDMA?
16. Write short notes on any four of the following :-
(a) FM Broadcasting;
(b) QPSK Modulation;
(c) Digital Audio Broadcasting;
(d) Swing equation;
(e) Control rod in nuclear reactor;
(f) Spinning reserve.
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