PGCB 2015 সালে অনুষ্ঠিত সহকারী ইলেকট্রিক্যাল ইঞ্জিনিয়ার (ইলেকট্রিক্যাল প্রশ্ন) নিয়োগ লিখিত পরীক্ষার প্রশ্ন এবং তার সমাধান দেওয়া হয়ছে। আপনি চাইলে পিডিএফ আকারেও ইলেকট্রিক্যাল প্রশ্ন ডাউনলোড করে নিতে পারেন সবার নিচে লিঙ্ক থেকে। এই (ইলেকট্রিক্যাল প্রশ্ন) প্রশ্ন গুলোই যে হয়েছে তার ১০০% গ্যারান্টি আমরা কখনো দিয়ে থাকি না। তবে বেশিরভাগ ক্ষেত্রেই মিল পাওয়া গিয়েছিলো।
Recruitment Test question Power Grid company of Bangladesh (PGCB)
Post: Assistant Engineer(Electrical)
Section-A General Knowledge
There are 60 question and answer all the question
Fill the circle or put tick mark on the circle of the Top Page for the correct answer of the following 60 question
1. When the ice floating in a glass of water melts, the level of Water will
a) Increase b) Decrease c) Remain constant d) First increase then decrease
2. If earth stops rotating, the impact on weight of a body will be minimum on which among the following places?
a) Equator b) North Pole c) Tropic of Cancer d) Tropic of Capricorn
3. Silk is produced by
a) Egg of silkworm b) Pupa of silkworm c) Larva of silkworm d) Insect itself
4. Which country has adopted “Bengali” language the status of second state language?
a) Sierra Leone b) South Africa c) Ivory coast d) Japan
5. Which of the following Environmentalists first gave the concept of Biodiveraity ‘hotspots”?
a) Gaylord Nelson b) Norman Myers c) John Muir d) Julia “Butterfly” Hill
6. Washing soda is the common name for
a) Calcium carbonate b) Calcium bicarbonate c) Sodium carbonate d) Sodium bicarbonate
7. Which among the following country is inside the European Union but Outside the Euro zone?
a) Slovakia b) Slovenia c) Spain d) Denmark
8. Which of the following type of Coal has maximum carbon content?
a) peat b)Lignite c) Bituminous d) Anthracite
9. Which of the following parts of the sun is easily visible only during a total solar eclipse?
a) Core b) photosphere c) sunspots d) corona
10. Who is the founder of Charukola Institute of Dhaka University?
a) Mazharul Islam b) Abudur Razzak c) Shamim Shikder d) Masum Ahmed
11. Any moving object on earth finally comes to rest due to which among the following?
a) Gravity b) Friction c) Inertia d) Momentum
12. Who is the administrative chief of any ministry of Government of Bangladesh?
a) Minister b) State Minister c) Secretary d) Additional Secretary
13. Spinach leaves are rich source of
a) Iron b) Vitamin A c) Carotene d) Vitamin E
14. Bangladesh University of Engineering was established
a) 1950 b) 1961 c) 1960 d) 1954
15. ESCAP stands for
a) European Society Council for Africa and Pacific b) Economic and Social Commission for Africa and Pacific c) Economic and Social Commission for Asia and Pacific d) None of the above
16. Evaluate the following limit: lim(x-0)((1-e^2x)/4x)
a) – ∞ b) – ¾ c) 0 d) ¼
17. What is the radius of a sphere with a center at the origin and that passes through the point (8,6,1)
a) 10 b) 65 c) √101 d) 100
18. Which of the values of A that satisfies the expression: A ^- 6/8 = 0.001
a) 10 b) 100 c) 1000 d) 10000
19. What is the Laplace transform of e -at ?
a) 1/a b) 1/(s + a) c) a/s d) 1/(s – a)
20. If 2^x is 32, what is x^2 ?
a) 5 b) 10 c) 25 d) 100
21. How much longer in second is required to drive 1 mile at 40 mph than at 60 mph?
a) 5 b) 10 c) 20 d) 30
22. Which one of the following is NOT a computer language?
a) MS-Excel b) BASIC c) COBOL d) Python
23. The scrambling of code is known as:
a) Encryption b) a firewall c) scrambling d) Password proofing
24. If the sums of three consecutive integers is less than 75, what is the greatest possible value of the smallest one?
a) 23 b) 24 c) 25 d) 26
25. What does DMA stand for?
a) Distinct Memory Access b) Direct Memory Access c) Direct Module Access d) Direct Memory Allocation
26. Programs stored in ROM are called
a) Hardware b) Software c) Firmware d) None of these
27. A fair coin is flipped three times. What is the probability that coin lands head each time?
a) 1/2 b) 1/3 c) 1/4 d) 1/8
28. ATM stands for?
a) Automatic Talking Machine b) Automatic Teller Machine c) Analog Teller Machine d) Automatic. Ticketing Machine
29. A list of instructions used by a computer is called
a) text b) CPU c) program d) output
30. Which of the following computer memory has shortest access time?
a) Secondary b) Magnetic core memory c) Cache memory d) RAM
31. Please be true __________ your word.
a) to b) for c) on d) at
32. Nasima’s passion __________ music is well known.
a) for b) to c) on d) with
33. Professor Hassan is overwhelmed __________ grief at his mother’s death.
a) to b) with c) for d) at
34. Invitation was limited __________ teachers only.
a) for b) with c) to d) on
35. Poverty is an obstacle __________ higher studies.
a) on b) with c) to d) at
36. Maheer is unequal __________ his task.
a) on b) for c) with d) to
37. Alberuni is in need __________ money.
a) for b) to c) from d) of
38. Ferdousi is qualified __________ the post of teacher.
a) to b) on c) at d) for
39. Rumi is zealous (eager) __________ freedom.
a) for b) to c) with d) on
40. Ehsanul Kabir was married __________ a pretty girl.
a) to b) with c) at d) for
41. I wondered __________ his ignorance.
a) to b) at c) with d) on
42. He is suspicious __________ my motive.
a) to b) of c) on d) with
43. He is a victim __________ earthquake disaster.
a) with b) to c) of d) on
44. Students should be respectful __________ their teachers.
a) with b) at c) to d) on
Section-B (Department) (ইলেকট্রিক্যাল প্রশ্ন)
Total 13 question and answer all of the question
(1) Tick the most appropriate answer: (i) The output efficiency and voltage regulation at the condition of maximum power transfer of a circuit, respectively, are
(a) 50% and 50% (b) 100% and 50% (c) 50% and 100% (d) 100% and 100%
Explanation: In power system maximum power transfer is never tried as huge amount of power in terms of MW are transferred from source to the load and the efficiency of transfer is 50% as will be seen shortly if power transferred is based on maximum power transfer criterion. Also under this, the terminal voltage becomes half of the source voltage and hence this results in poor voltage regulation, therefore, maximum power transfer criterion is never considered in power system. We will consider the theorem both for d.c. and a.c. circuits.[Reference: Network analysis and synthesis By Wadhwa C L]
(2) At what frequency will the output voltage VO (t) in the following figure be equal to the input voltage v(t)?
(a) 0 rad/s (b) 1 rad/s (c ) ∞ rad/s (d) None of the above
(3) Under a reverse-bias, the majority carriers in a p-n junction
(a) Moves toward the junction (b) Moves away from the junction (c) None of the above (d) Indeterminate
If the battery polarity is reversed as in Figure above (b) majority carriers are attracted away from the junction toward the battery terminals. The positive battery terminal attracts N-type majority carriers, electrons, away from the junction. The negative terminal attracts P-type majority carriers, holes, away from the junction.
This increases the thickness of the nonconducting depletion region. There is no recombination of majority carriers; thus, no conduction. This arrangement of battery polarity is called reverse bias.
(4) Input impedance of an OP-AMP is
(a) very low (b) very high (c) moderate (d) zero
Explanation: High input impedance at the input terminals and low output impedance at the output terminal(s) are particularly useful features of an op-amp.
(5)The maximum collector efficiency of a class-B power amplifier is
(a) 25% (b) 50% (c) 78.5% (d) 60%
(6) For a full wave rectifier circuit the diodes should be so chosen that
(a) the peak inverse voltage must be higher than the break down voltage of the diode (b) the peak inverse voltage must be lower than the break down voltage of the diode (c) the peak inverse voltage must be nearly equal to the break down voltage of the diode d) the peak inverse voltage cannot be related to the break down voltage of the diode.
Peak inverse voltage is the maximum or peak voltage that the diode can withstand when it is not conducting. That has an important analysis because in order to not enter into a break down we must always remember what the peak inverse voltage of a diode is because in the reverse bias condition when the reverse voltage is greater than a breakdown voltage it will enter into the breakdown and it will be suddenly rising.
But in all practicalities we do not have or we should not overcome that peak inverse voltage.
(7) In telephone systems. load is expressed in the unit of
(a) erlangs (b) decibels (c) bells (d) watts
(8) Cordless telephone using separate frequencies for transmission in base and portable units is known as
(a) duplex arrangement (b) half duplex arrangement (c) either (a) or (b) (d) neither (a) nor (b)
Explanation: Separate frequencies for transmission from base and portable units allows two way transmission and is called duplex arrangement.
(9) A telephone exchange has 9000 subscribers. If the number of calls originated is 10,000 in one hour, the calling rate is
(a) 0.9 (b) 10/9 (c) 0.81 (d) 0.1
Explanation: Calling rate is the number of calls per subscriber.
(10) In FM “guard band” is provided
(a) to limit upper frequency limit (b) to limit lower frequency limit (c) so that there is less adjacent channel inference (d) to limit transmitted power of station
(11) Two messages m1 and m2 have a probability of 0.5 each. The entropy is
(a) 0.25 (b) 0.5 (c) 0.75 (d) 1
Explanation: Entropy = 0.5 log2 2 + 0.5 log2 2 = 1
(12) The main function of a fuse is to
(a) Protect the line (b) Open the circuit (c)Protect the appliance (d) Prevent excessive currents
(13) Synchronous motor can operate at
(a) Lagging power factor (b)Leading power factor only (c)Unity power factor only (d)All of the above
(14) The damping winding in a synchronous motor is generally used
(a) To provide starting torque only (b) To reduce noise level (c) To reduce eddy currents (d) To prevent hunting and provide the starting torque
(15) In DC generator, the electricity produced in armature is
(a) DC (b) AC (c) Armature is not present in DC generator (d) None of the above
(16) A thermal protection switch can protect against
(a) Short-circuit (b)Temperature (c) Overload (d) Over voltage
(17) The arc voltage produced in circuit breaker is
(a) Leading the arc current by 90 degree (b) Lagging the arc current by 90 degree (c) In phase with the arc current (d) In phase opposition to the arc current
(18) When a 200 Ω load resistor is connected across the secondary winding of a transformer with a turns ratio of 4, the source sees a reflective load of
(a) 50 Ω (b) 12.5 Ω (c) 800 Ω (d) 3200 Ω
(19) The magnetizing inrush current in an unloaded transformer is maximum when the switch Is closed with the voltage passing through
(a) zero (b) positive maximum (c) negative maximum (d) all of the above
Explanation: If transformer is frequently switching, inrush current can cause the isolation brake because random switching could hit the moment when inrush current has maximal value (this is the moment when switch occurs in time when phase voltage is equal to zero).
(20) Potential across the various discs of suspension type insulator is different because of
(a) series capacitance (b) shunt capacitance (c) tower height (d)none of the above
(21) Most of the faults in a power system are
(a) three phase fault (b) double line to ground fault (c) line to ground fault (d) both (a) and (c)
Explanation: Typically, only 5% of the initial faults in a power system, are three phase faults with or without earth. Of the unbalanced faults, 80 % are line-earth and 15% are double line faults with or without earth and which can often deteriorate to 3 phase fault. Broken conductor faults account for the rest.
(22) Transformers are rated at KVA instead of KW because
(a) Load power factor is often not known (b) KVA is fixed whereas KW depends on load power factor. (c) Total transformer loss depends on volt ampere (d) It has become customary
Explanation: Electrical apparatus or machine is usually rated at the load, which can carry without overheating and damage to insulation i.e. rating of electrical machine is governed by the temperature rise caused by internal losses. The copper losses in transformer windings depends upon the strength of the output current and core loss on voltage. And thus these losses are impediment of power factor and the transformer are rated in KVA instead of KW.
Department Math (ইলেকট্রিক্যাল প্রশ্ন)
1. Determine Req in the following circuit:
2. The switch in the following circuit has been closed for a long time, and it is opened at t=0. Find v(t) for t ≥ 0.
3. Calculate the output voltage of the following amplifier. Input signals are V1 = 0.3 cos ώt and V2 = 0.2 cos ώt
4. For the NMOS shown bellow, show the input output connections for (i) Common Gate (ii) Common Drain and (iii) Common Source amplifier.
5. Draw the spectrum of x(t) of the system shown below:
6. Find Characteristics equation of the following:
7. What is meant by load angle of an alternator? Upon what factors does the load angle depend?
8. How do the synchronizing lamps indicate the correctness of phase sequence between existing and incoming alternators?
9. Why a synchronous motor is a constant speed motor?
10. A 3-phase, 50 Hz, 400 V motor develops 74 6 kW, the power factor being 0.75 lagging and efficiency 93%. A bank of capacitors is connected in delta across the supply terminals and power factor raised to 0.95 lagging. Determine the kVAR rating of the capacitors, connected in each phase.
11. Draw a diagram for a biased differential protection scheme for a unit connection.
12. The sending end voltage of a transmission line as a function of receiving end voltage and current is expressed as follows
VS=A Vr+B Ir, Let, A= |A| ∠α° , B = |B| ∠β°, Vr= |Vr| ∠0° ,
Vs = |Vs| ∠0°
Obtain expression for real & reactive power in terms of their quantities.
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