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## Interview MCQ Set 1

1. The unequal voltage distribution across individual unit of string of suspension insulator is __________
a) desirable and expressed by string efficiency
b) undesirable and expressed by string efficiency
c) desirable and expressed by impulse ratio
d) undesirable and expressed by impulse ratio

Answer: b [Reason:] The unequal potential distribution is undesirable and is expressed in terms of string efficiency. Impulse ratio is calculated during Impulse Frequency Flash Over Test. Impulse ratio is the ratio of impulse park over voltage to Spark over voltage at power frequency.

2. Glass insulator cannot be used for voltage above __________
a) 25 KV
b) 11 KV
c) 33 KV
d) 50 KV

Answer: d [Reason:] Glass is cheaper than porcelain in the simplest shapes and if properly toughened and annealed gives high resistivity and dielectric strength. The main disadvantage of Glass is that moisture more readily condenses on its surface and facilitates the accumulation of dust deposit thus giving a high surface leakage. Hence, glass insulators can be used upto 25 KV under ordinary atmosphere and well upto 50 KV in dry atmosphere.

3. Which of the following location is suitable to use shackle insulator?
a) Sharp Turn in transmission line
b) Dead end of low voltage distribution line
c) For bearing High Voltage transmission line conductor
d) Dead end of EHV transmission line

Answer: b [Reason:] Shackle insulator are almost universally used for low voltage lines. They can be used at all positions either intermediate terminal or angle where the angle exceed 60 degree deviation. They are generally used in conjunction with shackle sharps.

4. Which of the following insulator is used for insulating stay wire from pole?
a) Pin type insulator
b) Shackle insulator
c) Suspension insulator
d) Stay insulator

Answer: d [Reason:] Stay insulators are also called as guy insulators and are used in guy cables. Because it is necessary to insulate the lower part of the guy cable from pole for safety of people and animals on the ground.

5. What is the reason for unequal distribution of voltage among different unit of suspension insulator?
a) Unequal capacitance of different units
b) Unequal distribution of charging current caused by stray capacitance
c) Unequal resistivity of different units
d) Dirt deposited over the insulator disc

Answer: b [Reason:] The capacitance due to two metal fittings on either side of insulator is known as the mutual capacitance and the capacitance between these metal fittings and earthed pole or tower is known as shunt capacitance. Due to shunt capacitance charging current is not the same through all the discs of strings. So voltage being directly proportional to the current flowing through them will be different.

6. Arcing horns are used for ______________
a) protecting insulators from birds
b) protecting insulators from cracking or breaking due to flash over
c) improving string efficiency
d) protecting insulator from deposition of dirt

Answer: b [Reason:] During flash over insulators are cracked or broken up due to the heat of Arc. Grading ring in addition to equalization of voltage distribution across the insulators unit when used in conjunction with Arcing horns protects the insulator string from flashover. It does so by keeping the arc away from the insulator string until it is interrupted by protecting devices.

7. What is the effect of rain on string efficiency?
a) It becomes very low
b) It reduces slightly
c) It does not changes
d) It is improved

Answer: d [Reason:] Due to rain insulators becomes wet and mutual capacitance increases while the shunt capacitance remains constant thereby decreasing the value of k. As k is inversely related to string efficiency so, string efficiency is improved. K is the ratio of stray capacitance to mutual capacitance.

8. A suspension string have 3 units. Voltage across topmost and lower most unit of string are 6.71 volts and 11 volts respectively. What is the voltage across middle string, if voltage across whole string is 25.76 volts?
a) 103.47 volts
b) 8.05 volts
c) 83.6 volts
d) 25.76 volts

Answer: b [Reason:] Voltage across whole string is equal to the sum of voltage across each unit. From this the voltage across middle unit can be calculated.

9. If voltage across lowermost unit of a string is 34.8% of voltage across whole string and string efficiency is 57.46%. What is the voltage across whole string.
a) 100%of line voltage
b) 43.64% of line voltage
c) 75.2% of line voltage
d) 92.26% of line voltage

Answer: a [Reason:] Voltage across string is equal to the line voltage of conductor. So it is 100% of line voltage.

10. By using which of the following method hundred percent string efficiency can be achieved?
a) Using long cross arms
c) Static shielding
d) 100% string efficiency cannot be achieved

Answer: d [Reason:] 100% string efficiency can only be achieved by making voltage distribution across each unit of string equal. In practice it is impossible to attain such uniform voltage distribution. So 100% string efficiency cannot be achieved with any of the above methods.

## Interview MCQ Set 2

1. Which of the following term is appropriate to the below figure ? a) Large Data
b) Big Data
c) Dark Data
d) None of the mentioned

Answer: b [Reason:] Big data is a broad term for data sets so large or complex that traditional data processing applications are inadequate.

2. Point out the correct statement:
a) Machine learning focuses on prediction, based on known properties learned from the training data
b) Data Cleaning focuses on prediction, based on known properties learned from the training data.
c) Representing data in a form which both mere mortals can understand and get valuable insights is as much a science as much as it is art
d) None of the Mentioned

Answer: d [Reason:] Visualization is becoming a very important aspect.

3. Which of the following characteristic of big data is relatively more concerned to data science ?
a) Velocity
b) Variety
c) Volume
d) None of the Mentioned

Answer: b [Reason:] Big data enables organizations to store, manage, and manipulate vast amounts of disparate data at the right speed and at the right time.

4. Which of the following analytical capabilities are provide by information management company ?
a) Stream Computing
b) Content Management
c) Information Integration
d) All of the Mentioned

Answer: d [Reason:] With stream computing, store less, analyze more and make better decisions faster.

5. Point out the wrong statement:
a) The big volume indeed represents Big Data
b) The data growth and social media explosion have changed how we look at the data
c) Big Data is just about lots of data
d) All of the Mentioned

Answer: c [Reason:] Big Data is actually a concept providing an opportunity to find new insight into your existing data as well guidelines to capture and analysis your future data.

6. Which of the following step is performed by data scientist after acquiring the data ?
a) Data Cleansing
b) Data Integration
c) Data Replication
d) All of the Mentioned

Answer: a [Reason:] Data cleansing, data cleaning or data scrubbing is the process of detecting and correcting (or removing) corrupt or inaccurate records from a record set, table, or database.

7. 3V’s are not sufficient To describe big data.
a) True
b) False

Answer: a [Reason:] IBM data scientists break big data into four dimensions: volume, variety, velocity and veracity.

8. Which of the following focuses on the discovery of (previously) unknown properties on the data ?
a) Data mining
b) Big Data
c) Data wrangling
d) Machine Learning

Answer: a [Reason:] Data munging or data wrangling is loosely the process of manually converting or mapping data from one “raw” form into another format that allows for more convenient consumption of the data with the help of semi-automated tools.

9. Which of the following language should be replaced with the question mark in the below figure ? a) Java
b) PHP
c) COBOL
d) None of the mentioned

Answer: a [Reason:] Java is used for processing data in Big data Analytics.

10. Beyond Volume, Variety and Velocity is the Issue of Big Data Veracity
a) True
b) False

Answer: a [Reason:] Data Veracity is uncertain or imprecise data.

## Interview MCQ Set 3

1. What is the range for the stator slot pitch for the large hydro-electric generators?
a) 50-60 mm
b) 50-70 mm
c) 50-80 mm
d) 50-90 mm

Answer: d [Reason:] The minimum value for the stator slot pitch for the large hydro-electric generators is 50 mm. The maximum value for the stator slot pitch for the large hydro-electric generators is 90 mm.

2. When is the range of the number of slots per pole per phase in the salient pole machines?
a) 2-3
b) 3-4
c) 2-4
d) 2-6

Answer: c [Reason:] The minimum value of the number of slots per pole per phase is 2. The maximum value of the number of slots per pole per phase is 4.

3. Fractional windings are invariably used in synchronous machines?
a) true
b) false

Answer: a [Reason:] Fractional slot windings reduces the distribution factor for higher harmonics thus reducing their corresponding generated emfs and making the voltage nearly sinusoidally. Fractional slot windings are invariably used in synchronous machines.

4. What is the relation between coil span and harmonics?
a) low coil span decreases harmonics to less amount
b) low coil span decreases the harmonics drastically
c) high coil span decreases the harmonics drastically
d) high coil span decreases the harmonics by small amount

Answer: b [Reason:] The coil span is kept low in order to decreases the harmonics. The advantage of having lower coil spans is that it reduces the harmonics drastically.

5. The coil span should be 8.33 percent of pole pitch to obtain the maximum reduction of harmonics?
a) true
b) false

Answer: a [Reason:] The coil span adjustment indirectly affects the harmonics reduction. The coil span should be minimum of about 8.33 percent of pole pitch to obtain the maximum reduction of harmonics.

6. When is the formula for the flux per pole?
a) flux per pole = average magnetic field * pole pitch * length of the core
b) flux per pole = average magnetic field / pole pitch * length of the core
c) flux per pole = average magnetic field * pole pitch / length of the core
d) flux per pole = 1 / average magnetic field * pole pitch * length of the core

Answer: a [Reason:] To obtain the value of flux per pole first the average magnetic field is obtained. Then the pole pitch and the length of the core is obtained to obtain the flux per pole.

7. What is the formula for the turns per phase in the armature design?
a) turns per phase = voltage per phase * parallel paths per phase / 4.44 * flux density * frequency * winding space factor
b) turns per phase = voltage per phase / parallel paths per phase * 4.44 * flux density * frequency * winding space factor
c) turns per phase = voltage per phase * parallel paths per phase * 4.44 * flux density * frequency * winding space factor
d) turns per phase = voltage per phase * parallel paths per phase * 4.44 * flux density / frequency * winding space factor

Answer: a [Reason:] For obtaining the turns per phase, the voltage per phase is obtained along with the parallel paths per phase. Next the winding space factor is calculated and the substitution in the formula gives the turns per phase.

8. What is the formula for current in each conductor?
a) current in each conductor = kVA * 103 * 3 * voltage per phase
b) current in each conductor = kVA / 103 * 3 * voltage per phase
c) current in each conductor = kVA * 103 / 3 * voltage per phase
d) current in each conductor = kVA * 103 * 3 / voltage per phase

Answer: c [Reason:] The kVA output is first obtained from the operation of the machine. Next the voltage per phase is calculated to obtain the current in each conductor.

9. What is the permissible current density in the armature conductors?
a) 3-4 A per mm2
b) 3-6 A per mm2
c) 4-6 A per mm2
d) 3-5 A per mm2

Answer: d [Reason:] The minimum permissible value of the current density in the armature conductors is 3 A per mm2. The maximum allowed value of the current density in the armature conductors is 6 A per mm2.

10. What is the formula for the area of cross section of armature conductors?
a) area of cross section = current per conductor * current density in the armature conductors
b) area of cross section = current per conductor + current density in the armature conductors
c) area of cross section = current per conductor – current density in the armature conductors
d) area of cross section = current per conductor / current density in the armature conductors

Answer: d [Reason:] For obtaining the area of the cross section the current per conductor is calculated. Next the current density is calculated and the ratio of both gives the current density of the area of cross section.

## Interview MCQ Set 4

1. An isolated generator connected to a turbine with its continuous maximum power of 20 MW, 50 Hz. Generator connected with two loads of 8 MW, each operate at 50 Hz.. Generator has 5% droop characteristic. If an additional load of 6 MW is added then the change in the frequency will be ____________
a) 0.25
b) 0.75
c) 0.5
d) 1

Answer: a 2. For the given system the Ybus matrix is show below.  d) None of the mentioned

Answer: a [Reason:] Y11=j2+(1/5j) = 1.8j Y12=-(1/5j) = 0.2j; Y13=0 Hence option ‘a’ is most applicable.

3. If short TL is delivering a lagging power factor load, sending end p.f. would be ________
a) (VrcosФr+IR)/Vs
b) (VrcosФr+IRsinФr)/Vs
c) (VrsinФr+IR)/Vs
d) (VssinФr+IRcosФr)/Vs

Answer: a [Reason:] The phasor diagram is given below 4. If all the sequence voltages at the fault point in a power system are equal, then fault is __________
a) LLG fault
b) LG fault
c) Three phase to ground fault
d) Line to Line fault

Answer: a [Reason:] It is LLG fault.

5. The below mentioned graph is a recorded data of the voltage fluctuation of the network, then it can be concluded that these faults are __________ a) L-G
b) A three phase motor short
c) Feeder fault
d) Any of the mentioned

Answer: a [Reason:] The sudden dip is the LG fault in the graph as the dips are not very large and the system is maintaining its stability.

6. The inertia constant of two groups of machines which do not swing together are 4 and 20 MJ/MVA, the equivalent inertia constant of the system is _________
a) 2.85
b) 14
c) 6
d) 12

Answer: a [Reason:] For the incoherent system, the equivalent inertia = H1H2/(H1+H2).

7. A fault current of 1500A passing through the primary side of a 400/5 CT. On the secondary side an inverse time over current relay is connected whose current setting is 75%, the plug setting is __________
a) 5
b) 3.75
c) 6
d) 4

Answer: a 8. The three phase line is working at 50 Hz with conductors rearranged as shown. The Cph of TL at 132 kV is ___________ a) 8.75*10-9
b) 8.75*10-12
c) 26.2*10-12
d) 26.2*10-9

Answer: a 9. For a 100 MVA, 11 kV three phase Alternator observes a three phase fault at terminals of it. If the fault current is 2000 A, the pu value of positive sequence reactance ______
a) 2.62
b) 0.46
c) 1.31
d) 0.92

Answer: a [Reason:] PU fault current = 2000/5248.63 = 0.381 pu 0.381 = 1/X X= 1/0.381 =2.62 pu.

10. A lossless TL having SIL of 3000 MW is provided with uniform distributed series capacitance compensation of 25% and shunt compensation of 30% then the SIL of compensated TL will be _______________
a) 3949.9
b) 3289
c) 2784.9
d) 2877.6

Answer: a [Reason:] SIL=(V2 )/Z SIL α 1/Z Zcomp = Zs√((1-kse)/((1+ksh)(1-Klsh))) Kse = 0.25; Klsh = 0; Kcsh = 0.3, Zcomp =0.7595 SILcomp = 0.7595*3000 = 3949.96 MVA.

11. A lossless TL having SIL of 3000 MW is provided with uniform distributed series capacitance compensation of 25% and shunt compensation of 30% then the compensated impedance of TL will be(in pu) ____________
a) 0.7595
b) 2.88
c) 0.647
d) 3.27

Answer: a [Reason:] SIL=(V2)/Z SIL α 1/Z Zcomp = Zs√((1-kse)/((1+ksh)(1-Klsh))) Kse = 0.25; Klsh = 0; Kcsh = 0.3, Zcomp =0.7595.

## Interview MCQ Set 5

1. How many ways are there to represent the Cusum on the Cusum charts?
a) 3
b) 4
c) 2
d) 5

Answer: c [Reason:] There are two ways invented for the representation of the Cusums on the Cusum charts; namely Tabular Cusum, and V-mask form of the Cusum.

2. Which of these is a name of any way to represent the Cusum charts?
a) Logarithmic
b) Algorithmic
c) Exponential
d) Normal

Answer: b [Reason:] There are two ways of representing the Cusums. The first one is the tabular (or Algorithmic) Cusum, and the second one is the V mask form of Cusum.

3. The tabular Cusums are made to monitor the ____ of the process.
a) Variance
b) Mean
c) Standard deviation
d) Capability

Answer: b [Reason:] The tabular Cusum is generally made to monitor the changes occurring in the mean of the process with respect to the time. This is preferred over the V-mask type.

4. Which of these is not one of the assumptions made for the construction of Tabular Cusum charts for the individual measurements?
a) The selected variable varies according to a lognormal distribution
b) The selected variable varies according to a normal distribution
c) The selected variable varies according to a binomial distribution
d) The selected variable varies according to an exponential distribution

Answer: b [Reason:] For the construction of the tabular cusum charts, it is assumed that the variable for which the Cusum charts are to be plotted, varies on a normal distribution.

5. Which of these is not an assumption made for the construction of the tabular Cusum charts?
a) The selected variable varies on a normal distribution
b) The mean of the normal distribution is available
c) The estimate or the exact value of the standard deviation of the variable
d) The assumptions are very inconsistent with phase II application of SPC

Answer: d [Reason:] Tabular Cusum charts are made with the assumptions that, the selected variable varies on normal distribution with a known mean and standard deviation. The standard deviation estimate may also be used.

6. If the process standard deviation increases, how will the cusum chart for monitoring process variability indicate the out-of-control state?
a) The value of Si+ will increase
b) The value of Si+ will decrease
c) The value of Si will decrease with decrease in the value of Si+
d) The value of Si will increase

Answer: a [Reason:] If the process standard deviation increases, Si+ value will be increased consequently. It will eventually exceed the decision interval h and we will get an out-of-control signal.

7. Which of these is an indication of out-of-control process with low standard deviation?
a) Increase in the value of Si+
b) Decrease in the value of Si+ with increase in the value of Si
c) Increase in the value of Si
d) Decrease in the value of Si with decrease in the value of Si

Answer: c [Reason:] If the process becomes out-of-control with low value of the process standard deviation, the value of Si will increase and eventually exceed the decision interval, h.

8. Who was the first person to recommend plotting the cusum charts for mean and standard deviation on same graph?
a) Hawkins
b) Roberts
c) Atkinson
d) Crowder

Answer: a [Reason:] Although it is customary to plot the cusum charts for mean and cusum charts for standard deviation on different graphs, Hawkins (1993a) was the first person who recommended to plot them on same graph.

9. If the deployment of the cusum is extended to the case of averages of the rational subgroups where sample size n>1, what will be done?
a) The value of xi be replaced by xi
b) The value of xi be replaced by xi
c) The value of Ci+ be replaced by value of Ci
d) The value of Ci be replaced by the value of Ci+

Answer: a [Reason:] When the rational subgrouping procedure is adopted with sample size n>1, the cusum charts are built by simply replacing xi by xi and σ by σ/√n.

10. A cusum for normal variance is having the value of upper cusum equal to ___ Answer: b [Reason:] The value of the upper cusum for the cusum for normal variance has the value of σ2 replaced by the sample variance Si2. It is expressed as, 11. A cusum for a normal variance has the value of lower cusum equal to ____ Answer: d [Reason:] The value of the lower cusum for the normal variance is denoted by C_i^-. It is expressed by the following formula, 12. If the value of Ci-1+S2+k is lesser than (-1), what will be the value of Ci equal to?
a) Lesser than -1
b) Higher than 1
c) Lower than 0
d) 0

Answer: d [Reason:] We know that Also the cusum values, whether it is the upper cusum, or lower cusum, are either zero or positive. So even if the value of Ci-1+S2+k is lesser than (-1), the value of Ci will be zero.

13. The V-mask procedure was proposed by ____
a) Crowder
b) Roberts
c) Brinson
d) Barnard

Answer: d [Reason:] There are two procedures to plot the cusum charts. One is called the tabular cusum, and the other is called the V-mask procedure. The V-mask procedure was first introduced by Barnard (1959).

14. Only the value of lower cusum can be negative.
a) True
b) False

Answer: b [Reason:] We know that the value of lower cusum is denoted by, So we get to know that the value of the lower cusum is always greater than or equal to zero.