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Interview MCQ Set 1

1. ____ function breaks up a string on the basis of delimiter.
a) length
b) substr
c) system
d) split

View Answer

Answer: d [Reason:] The split function breaks a substr str on the basis of delimiter. The syntax is split (stg, arr, ch) where stg is the string to be broken, ch is delimeter and arr is the array which stores the fields.

2. For running a UNIX command within awk, we’ve to use ____ function.
a) length
b) substr
c) system
d) split

View Answer

Answer: c [Reason:] For running a UNIX command within awk, we’ve to use system function. For example,

BEGIN 
{
      system(“date”)   // prints the system date 
}

3. sqroot(x) function returns the square root of x.
a) True
b) False

View Answer

Answer: b [Reason:] The sqrt(x) function is used for returning the square root of x.

4. Which of the following is supported by awk?
a) if
b) while
c) for
d) if, while, for

View Answer

Answer: d [Reason:] awk generally supports all the functions and features of a modern programming language. It provides if condition for control flow and while, for loop for repeatedly executing the instructions.

5. print statement is necessary for printing a line.
a) True
b) False

View Answer

Answer: b [Reason:] print statement is not necessary for printing a line. If the selection criteria is specified, the specified line is automatically printed.

6. awk uses _____ dimensional arrays.
a) one
b) two
c) multi
d) three

View Answer

Answer: a [Reason:] awk supports one-dimensional arrays where the array subscript can be a string also.

7. awk has some built-in functions which are used for arithmetic and string operations.
a) True
b) False

View Answer

Answer: a [Reason:] awk also has several built-in functions which are used for performing arithmetic as well as string operations. The arguments to these functions are passed in C style.

8. Which of the following is a built-in function for awk?
a) length
b) index
c) size
d) length and index

View Answer

Answer: a [Reason:] awk has several built-in functions which are used for performing arithmetic as well as string operations. The length function is used for determining the length of its argument while the index is used for determining the position of a string str1 within another string str2.

9. The _____ function extracts a substring from a string.
a) length
b) index
c) size
d) substr

View Answer

Answer: d [Reason:] The substr function is used for extracting a substring from a string. The syntax for using this function is substr (str,m,n) where str is the string from which extraction is done. m represents the starting point of extraction and n indicates the number of characters to be extracted.

10. awk makes a distinction between numeric and string variables.
a) True
b) False

View Answer

Answer: b [Reason:] awk has no procedure for a distinction between numeric and string variables. It can perform numeric computations for a string as well.

Interview MCQ Set 2

1. ____ system call is used for renaming a file, directory or symbolic link.
a) renam
b) rename
c) ren
d) change

View Answer

Answer: b [Reason:] The rename call is used for renaming any type of file. It can rename a file, a directory or a symbolic link.

2. S_IFxxx macros are used for checking the file types.
a) True
b) False

View Answer

Answer: a [Reason:] All UNIX systems provide a set of macros beginning with S_IF (often called S_IFxxx macros) that provide us with a function of checking the file type. But modern UNIX system performs this task in a more simplified manner using S_ISxxx macros.

3. Which of the following macro returns true if the file type is a directory?
a) S_ISREG
b) S_ISDIR
c) S_ISCHR
d) S_ISFIFO

View Answer

Answer: b [Reason:] The S_ISDIR macro returns true if the file type is a directory. The S_ISREG returns true if the file type is regular.

4. For checking a file access rights, ___ system call is used.
a) acc
b) access
c) axs
d) filert

View Answer

Answer: b [Reason:] By using the access system call, we can check the file’s access rights. It looks at the real UID and real GID of the user running the program and determines that whether the file is accessible by the real user.

5. Which of the following is used with access call for checking the owner’s permissions?
a) R_OK
b) W_OK
c) X_OK
d) R_OK, W_OK, X_OK

View Answer

Answer: d [Reason:] By using the access system call, we can check the file’s access rights. We’ve to specify one of the following four values to define the permission which is needed to be tested.

R_OK    -    read permission OK
W_OK    -    write permission OK
X_OK    -     execution permission OK
F_OK    -    file exists

6. chmod and fchmod calls are used for changing file permissions.
a) True
b) False

View Answer

Answer: a [Reason:] chmod and fchmod calls are used for changing the file permissions. Chmod uses pathname for identifying a file while fchmod uses the file descriptor.

7. Both the owner and group owner can be changed by ____ call.
a) chown
b) chgrp
c) chuser
d) ch

View Answer

Answer: a [Reason:] The chown system call is used to change both the owner and group owner. It has three states; chown, fchown, lchown.

8. For changing the time stamps, _____ system call is invoked.
a) atime
b) utime
c) mtime
d) ch

View Answer

Answer: b [Reason:] utime system call is used to change a file’s modification and access times.

9. System calls and library functions are same.
a) True
b) False

View Answer

Answer: b [Reason:] System calls are built into the kernel, but library functions are built on top of them. When a system call is invoked, the pre-processor switches to kernel mode and returns to the user mode when the call completes.

10. Which of the following system call uses file descriptor as an argument?
a) read
b) write
c) close
d) read, write, close

View Answer

Answer: d [Reason:] A file descriptor is an integer which is allocated when a file is opened. It is used by all system calls that perform some operations on file -like read, write, close, lseek.

Interview MCQ Set 3

1. What is the range of current density in the damper bars?
a) 3-4 A per mm2
b) 3-5 A per mm2
c) 3-6 A per mm2
d) 4-6 A per mm2

View Answer

Answer: a [Reason:] The minimum value of the current density in the damper bars is given to be 3 A per mm2. The maximum value of the current density in the damper bars is given to be 4 A per mm2.

2. What is the percentage of the damper windings slot pitch with respect to stator slot pitch?
a) 30%
b) 40%
c) 20%
d) 60%

View Answer

Answer: c [Reason:] The slot pitch of damper windings is 20% of the stator slot pitch. This is because to reduce the current induced in damper windings by tooth ripples.

3. What is the formula for the pole arc?
a) pole arc = number of bars per pole * stator slot pitch * 0.8
b) pole arc = number of bars per pole / stator slot pitch * 0.8
c) pole arc = number of bars per pole * stator slot pitch / 0.8
d) pole arc = 1 / number of bars per pole * stator slot pitch * 0.8

View Answer

Answer: a [Reason:] The number of bars per pole is calculated along with the stator slot pitch. Next all the values are multiplied by 0.8 and the pole arc value is obtained.

4.What is the formula for the length of each damper bar for small machines?
a) length of each damper bar = 1.1 * axial length
b) length of each damper bar = axial length + 0.1
c) length of each damper bar = axial length – 0.1
d) length of each damper bar = 1.1 / axial length

View Answer

Answer: a [Reason:] Length of each damper bar = 1.1 * axial length is the formula for the length of each damper bar for small machines. length of each damper bar = axial length + 0.1 is the formula for the length of each damper bar for large machines.

5. What is the formula for the area of cross-section of each damper bar?
a) area of cross section of each damper bar = total area of bars per pole – number of damper bars per pole
b) area of cross section of each damper bar = total area of bars per pole + number of damper bars per pole
c) area of cross section of each damper bar = total area of bars per pole / number of damper bars per pole
d) area of cross section of each damper bar = total area of bars per pole * number of damper bars per pole

View Answer

Answer: c [Reason:] The total area of bars per pole is first obtained. Next the number of damper bars per pole is calculated and the ratio gives the area of cross section of each damper bar.

6. What is the formula of the area of each ring short-circuiting the bars?
a) area of each ring short-circuiting the bars = (0.7-0.9) * area of damper bar
b) area of each ring short-circuiting the bars = (0.8-1) * area of damper bar
c) area of each ring short-circuiting the bars = (0.7-1) * area of damper bar
d) area of each ring short-circuiting the bars = (0.8-0.9) * area of damper bar

View Answer

Answer: b [Reason:] First the area of damper bars is calculated first. Next the area of damper bars is multiplied by a value between 0.8-1 to obtain the area of each ring short-circuiting the bars.

7. Given : total area = 473 mm2 and Number of bars = 8 for a rotor design, what is the value of area of each damper bar?
a) 59 mm2
b) 455 mm2
c) 475 mm2
d) 3784 mm2

View Answer

Answer: a [Reason:] Area of each bar = total area / number of bars Area of each bar = 473/8 = 59 mm2.

8. What is the formula for the height of pole shoe sufficient to accommodate the damper windings?
a) height of pole shoe = diameter of damper bars
b) height of pole shoe = 2 * diameter of damper bars
c) height of pole shoe = diameter of damper bars/2
d) height of pole shoe = 3 * diameter of damper bars/2

View Answer

Answer: b [Reason:] First the diameter of the damper bars is calculated. It is then multiplied by 2 to get the height of pole shoe.

9. The pole profile drawing helps in obtaining the various dimensions of the pole?
a) true
b) false

View Answer

Answer: a [Reason:] The pole profile drawing is essential to obtain the design characteristics of the rotor. It helps in the process of obtaining the various dimensions of the pole.

10. The pole shoe drawing is completed by fixing the height of pole shoe?
a) true
b) false

View Answer

Answer: a [Reason:] The pole shoe surface can be drawn with the armature surface being fixed. The pole shoe drawing is completed by fixing the height of pole shoe.

Interview MCQ Set 4

1. A protection system engineer is planning to provide the complete protection, he can achieve this by ___________
a) three phase fault relays and two earth fault relays
b) two phase fault relays and three earth fault relays
c) a two phase fault relays and three earth fault relays
d) a two phase fault relays and two earth fault relays

View Answer

Answer: a [Reason:] For the complete protection of the power system, one can use 3 phase fault relays and two earth fault relays so that to cover the entire zone of operation.

2. The given figure shows protection system scheme for one phase of generator. A high resistance fault occurs near the neutral end with the current distribution as marked. The slope of the relay is 10% and pick-up current of 0.15A.
The CT ratio is 500/5.
Will the relay operate under given circumstances?
a) True
b) False

View Answer

Answer: b [Reason:] Ioc = i1-i2 IRS = (i1+i2)/2 Relay will operate only if iR > k(i1+i2)/2+i0 I1 = 435/(500/5) I2 = 400/(500/5) Ir = i1-i2 = 4.35-4.0 = 0.35 A i1+i2 = 4.175 A k(i1+i2)/2+i0 = 0.1*4.175 + 0.15 = 0.5675 > 0.35 Therefore, the relay will operate.

3. We need the biasing of differential relay biased to avoid mal operation when used for transformer protection due to ____________
a) mismatch of CT
b) saturation of
c) difference in connection of both sides of CT
d) current setting mismatch

View Answer

Answer: a [Reason:] It is not practical to use CT of exact type, so the mal operation may occur due to mismatch of current transformers.

4.If the specified fault setting for a winding is mentioned as 20%, then what can be inferred about it?
a) If a terminal fault has its current limited to the full load rating, then 20% of winding from neutral end will be unprotected
b) If a terminal fault has its current limited to the full load rating, then 80% of winding from neutral end will carry current
c) If a terminal fault has its voltage limited to the full load rating, then 20% of winding from neutral end will be unprotected
d) Any of the mentioned

View Answer

Answer: a [Reason:] The fault setting implies that 20% of the neutral is unprotected.

5. The typical characteristic of the relay during loss of excitation is ____________
a)advanced-power-systems-questions-answers-q5
b)power-systems-questions-answers-switchgear-protection-2-q5-a
c)power-systems-questions-answers-switchgear-protection-2-q5-c
d)power-systems-questions-answers-switchgear-protection-2-q5-d

View Answer

Answer: a [Reason:] The loss of excitation leads to a characteristic of the negative resistance offered.

6. The standard system fault characteristic of the relay is _____________
a)power-systems-questions-answers-switchgear-protection-2-q6-a
b)power-systems-questions-answers-switchgear-protection-2-q6-b
c)power-systems-questions-answers-switchgear-protection-2-q6-c
d)power-systems-questions-answers-switchgear-protection-2-q6-d

View Answer

Answer: a [Reason:] The typical fault characteristic shown by a relay is the linear impedance offered by the fault currents.

7. A longitudinal differential protection on stator can detect inter-turn on the stator.
a) True
b) False

View Answer

Answer: b [Reason:] Because inter-turn faults on the same phase of stator wdg does not disturb the balance between currents in neutral and high voltage CTs. Hence a transverse differential protection is used.

8. Bias is used in the relay protection to _______________
a) provide balanced sharing of current
b) reduce current level
c) deivert the current
d) none of the mentioned

View Answer

Answer: a [Reason:] Bias is predominantly used for providing the balance in the current distribution.

9. Unbalancing of an alternator may occur due to ____________
a) single phase fault
b) unbalanced loading
c) line breaking
d) all of the mentioned

View Answer

Answer: d [Reason:] All the mentioned reasons can cause unbalancing.

10. For the given earth fault for solidly earthed CT, the fault current as a percentage of the full load current is given as _______________
power-systems-questions-answers-switchgear-protection-2-q10
a)power-systems-questions-answers-switchgear-protection-2-q10-a
b)power-systems-questions-answers-switchgear-protection-2-q10-b
c)power-systems-questions-answers-switchgear-protection-2-q10-c
d)power-systems-questions-answers-switchgear-protection-2-q10-d

View Answer

Answer: a [Reason:] The line current in the delta side will rise from zero and star connection will have maximum current.

Interview MCQ Set 5

1. How many types of cooling methods are available for transformer?
a) 3
b) 2
c) 1
d) 4

View Answer

Answer: a [Reason:] There are 3 types of cooling methods available for transformers. They are natural cooling, air blast cooling, forced oil circulation.

2. How are the radiators cooled in the present time?
a) by natural cooling
b) by forced cooling using small fans
c) by forced cooling using large fans
d) by using external air

View Answer

Answer: b [Reason:] At present time the radiators are cooled using forced cooling. The forced cooling takes place with the help of the small fans mounted on each radiator.

3. What type of cooling is being made use of in transformers having a capacity of less than 11MVA?
a) natural cooling
b) forced cooling
c) air blast cooling
d) forced cooling and air blast cooling

View Answer

Answer: a [Reason:] For transformers having capacity less than 11MVA, natural cooling is made use of. For transformers having capacity more than 11MVA, air blast cooling is used.

4. Compared to the natural cooling, how much of heat dissipation is increased by air blast cooling?
a) 50-70%
b) 60-70%
c) 50-60%
d) 40-60%

View Answer

Answer: c [Reason:] Air blast cooling helps in increased heat dissipation. The minimum value of increased heat dissipation is 50% and maximum value is 60%.

5. Increase in the velocity of oil circulation increases the transformer output?
a) true
b) false

View Answer

Answer: a [Reason:] The increases in velocity of the air circulation increases the temperature. The temperature rise increases the transformer output.

6. What is the relation of the increase of the oil circulation rate with energy losses?
a) increase of the oil circulation rate is not depending with energy losses
b) increase of the oil circulation rate is directly proportional to the energy losses
c) increase of the oil circulation rate is directly proportional to the square of energy losses
d) increase of the oil circulation rate is indirectly proportional to energy losses

View Answer

Answer: b [Reason:] The increase in the oil circulation rate is unsuitable because this increases the large energy losses In the pumping unit. To cool the oil, it is circulate through a special oil cooler.

7. What is the flow rate of the circulating oil in an air cooler with natural air cooling?
a) 12.5 litre per minute per KW of losses
b) 12 litre per minute per KW of losses
c) 14 litre per minute per KW of losses
d) 13 litre per minute per KW of losses

View Answer

Answer: b [Reason:] When natural air cooling is used, the flow rate is 12 litres per minute per KW of losses. Even when the air blast cooling is used, the transformer output increases roughly to the same extent.

8. What is the range of the cooler surfaces per 1 KW of losses?
a) 0.1-0.25 m2
b) 0.18-0.2 m2
c) 0.1-0.2 m2
d) 0.18-0.25 m2

View Answer

Answer: d [Reason:] The minimum value of the cooler surfaces per 1 KW of losses is 0.18 m2. The maximum value of the cooler surfaces per 1 KW of losses is 0.25 m2.

9. What is the range of the flow rate of circulating oil per KW of losses?
a) 6-7 liters per minute
b) 5-6 liters per minute
c) 6-8 liters per minute
d) 6-7 liters per minute

View Answer

Answer: c [Reason:] The minimum value of the flow rate of circulating oil per KW of losses is derived to be 6 liters per minute. The maximum value of the flow rate of circulating oil per KW of losses is derived to be 8 liters per minute.

10. The temperature difference between the incoming and outgoing water is greater than 100C?
a) true
b) false

View Answer

Answer: b [Reason:] The water flow rate is about 1.5 litres per minute. The difference in temperature between the incoming water and outgoing water is 100C.

11. What is the formula for width of the tank for single phase transformers used?
a) width of tank = 2*distance between adjacent limbs + external diameter of h.v windings + 2*clearance between h.v windings and tank
b) width of tank = distance between adjacent limbs + external diameter of h.v windings + 2*clearance between h.v windings and tank
c) width of tank = 2*distance between adjacent limbs * external diameter of h.v windings + 2*clearance between h.v windings and tank
d) width of tank = distance between adjacent limbs * external diameter of h.v windings + 2*clearance between h.v windings and tank

View Answer

Answer: b [Reason:] Width of tank = 2*distance between adjacent limbs + external diameter of h.v windings + 2*clearance between h.v windings and tank is the formula for three phase transformer. For single phase transformers, the distance between adjacent limbs is not multiplied.

12. What is the formula for the length of the tank?
a) length of the tank = external diameter of h.v winding + clearance on each side between the winding and tank along the width
b) length of the tank = external diameter of h.v winding * clearance on each side between the winding and tank along the width
c) length of the tank = external diameter of h.v winding + 2*clearance on each side between the winding and tank along the width
d) length of the tank = external diameter of h.v winding / 2*clearance on each side between the winding and tank along the width

View Answer

Answer: c [Reason:] The external diameter of h.v winding is obtained. Next the clearance on each side between the winding and tank along the width is calculated and is substituted in the above formula.

13. What is the formula for height of transformer tank?
a) height of transformer tank = Height of transformer frame + clearance height between the assembled transformer and tank
b) height of transformer tank = Height of transformer frame * clearance height between the assembled transformer and tank
c) height of transformer tank = Height of transformer frame / clearance height between the assembled transformer and tank
d) height of transformer tank = Height of transformer frame – clearance height between the assembled transformer and tank

View Answer

Answer: a [Reason:] Firstly, the height of the transformer frame is calculated. Next, the clearance height between the assembled transformer and tank is also calculated. Substitute the values to obtain the height of transformer tank.

14. What is the rating of the transformer for the voltage of about 11 kV?
a) 1000-2000 kVA
b) 100-3000 kVA
c) 1000-5000 kVA
d) 100-500 kVA

View Answer

Answer: c [Reason:] The minimum value of the rating of the transformer for a voltage of about 11 kV should be 1000 kVA. The maximum value of the rating of the transformer for a voltage of about 11 kV should be about 5000 kVA.

15. What is the rating of the transformer for the voltage of above 11 kV upto 33 kV?
a) 1000-5000 kVA
b) less than 1000 kVA
c) above 1000 kVA
d) 100-500 kVA

View Answer

Answer: b [Reason:] 1000-5000 kVA is the rating of the transformer for the voltage of about 11 kV. When the voltage rating is about 11-33 kV, then the rating of the transformer is less than 1000 kVA.