Electrical Interview questions Part 7

Electrical interview question:What is Automatic Voltage regulator(AVR)?
Answer:AVR is an abbreviation for Automatic Voltage Regulator.It is important part in Synchronous Generators, it controls theoutput voltage of the generator by controlling its excitation current. Thus it can control the output Reactive Power of the Generator.

Electrical interview question:What is an exciter and how does it work?
Answer:There are two types of exciters, static exciter and rotory exciter.purpose of excitor is to supply the excitation dc voltage to the fixed poles of generator.Rotory excitor is an additional small generator mounted on the shaft of main generator. if it is dc generator, it will supply dc to the rotory poles through slip ring and brushes( conventional alternator). if it is an ac excitor, out put of ac excitor is rectified by rotating diodes and supply dc to main fixed poles.ac excitor is the ac generator whose field winding are stationary and armature rotates. initial voltage is built up by residual magnetism.It gives the starting torque to the generator.

Electrical interview question:Difference between a four point starter and three point starter?
Answer:The shunt connection in four point stater is provided separately form the line where as in three point stater it is connected with line which is the drawback in three point stater

Electrical interview question:Why use the VCB at High Transmission System ? Why can't use ACB?
Answer:Actually the thing is vacuum has high arc queching property compare to air because in VCB ,the die electric strengths equal to 8 times of air . That y always vaccum used as inHT breaker and air used as in LT .

Electrical interview question:What is the difference between surge arrestor and lightning arrestor?
Answer:LA is installed outside and the effect of lightning is grounded,where as surge arrestor installed inside panels comprising of resistors which consumes the energy and nullify the effect of surge.

Electrical Interview questions Part 6

Electrical interview question:Why syn. generators r used for the production of electricity?
Answer:synchronous machines have capability to work on different power factor(or say
different imaginary power varying the field emf. Hence syn. generators r used for the production of electricity.

Electrical interview question:What is the difference between synchronous generator & asynchronous generator?
Answer:In simple, synchronous generator supply's both active and reactive power but asynchronous generator(induction generator) supply's only active power and observe reactive power for magnetizing.This type of generators are used in windmills.

Electrical interview question:1 ton is equal to how many watts?
Answer:1 ton = 12000 BTU/hr and to convert BTU/hr to horsepower,
12,000 * 0.0003929 = 4.715 hp therefore 1 ton = 4.715*.746 = 3.5 KW.

Electrical interview question:why syn. generators r used for the production of electricity?
Answer:synchronous machines have capability to work on differentpower factor(or say
different imaginary pow varying the field emf. Hence syn. generators r used for the production of electricity.

Electrical interview question:Enlist types of dc generator?
Answer:D.C.Generators are classified into two types 1)separatly exicted d.c.generator 2)self exicted d.c.generator, which is further classified into;1)series 2)shunt and
3)compound(which is further classified into cumulative and differential).

Electrical Interview questions Part 5

Electrical interview question:Give two basic speed control scheme of DC shunt motor?
Answer:1. By using flux control method:in this method a rheostat is connected across the field winding to control the field current.so by changing the current the flux produced by the field winding can be changed, and since speed is inversely proportional to flux speed can be controlled 2.armature control method:in this method a rheostat is connected across armature winding by varying the resistance the value of resistive drop(IaRa)can be varied,and since speed is directly proportional to Eb-IaRa the speed can be controlled.

Electrical interview question:what is the principle of motor?
Answer:Whenever a current carrying conductor is placed in an magnetic field it produce turning or twisting movement is called as torque.

Electrical interview question:what is meant by armature reaction?
Answer:The effect of armature flu to main flux is called armature reaction. The armature flux may support main flux or opposes main flux.

Electrical interview question:Give two basic speed control scheme of DC shunt motor?
Answer:1. By using flux control method:in this method a rheostat is connected across the field winding to control the field current.so by changing the current the flux produced by the field winding can be changed, and since speed is inversely proportional to flux speed can be controlled 2.armature control method:in this method a rheostat is connected across armature wdg.by varying the resistance the value of resistive drop(IaRa)can be varied,and since speed is directly proportional to Eb-IaRa the speed can be controlled.

Electrical interview question:what is the difference between synchronous generator & asynchronous generator?
Answer:In simple, synchronous generator supply's both active and reactive power but asynchronous generator(induction generator) supply's only active power and observe reactive power for magnetizing.This type of generators are used in windmills.

Electrical interview question:What is the Polarization index value ? (pi value)and simple definition of polarization index ?
Answer:Its ratio between insulation resistance(IR)i.e meggar value
for 10min to insulation resistance for 1 min. It ranges from 5-7 for new motors & normally for motor to be in good condition it should be Greater than 2.5 .

Electrical Interview questions Part 4

Electrical interview question:What will happen when power factor is leading in distribution of power?
Answer:If their is high power factor, i.e if the power factor is close to one:
1.losses in form of heat will be reduced,
2.cable becomes less bulky and easy to carry, and very
cheap to afford, &
3. it also reduces over heating of tranformers.

Electrical interview question:whats the one main difference between UPS & inverter ? And electrical engineering & electronics engineering ?
Answer:uninterrupt power supply is mainly use for short time . means according to ups VA it gives backup. ups is also two types : on line and offline . online ups having high volt and amp for long time backup with with high dc voltage.but ups start with 12v dc with 7 amp. but inverter is startwith 12v,24,dc to 36v dc and 120amp to 180amp battery with long time backup.

Electrical interview question:What is 2 phase motor?
Answer:A two phase motor is a motor with the the starting winding and the running winding have a phase split. e.g;ac servo motor.where the auxiliary winding and the control winding have a phase split of 90 degree.

Electrical interview question:Advantages of vvvf drives over non vvvf drives for EOT cranes?
Answer:1.smooth start and stop.
2.no jerking of load.
3.exact posiitoning
4.better protection for motor.
5.high/low speed selection.
6.reliability of break shoe.
7.programmable break control.
8.easy circutry
9.reduction in controls
10.increases motor life

Electrical interview question:What is the significance of vector grouping in Power Transformers?
Answer:Every power transformer has a vector group listed by its manufacturer. Fundamentally it tells you the information about how the windings are connected (delta or wye) and the phace difference betweent the current and voltage. EG. DYN11 means Delta primary, Wye Secondry and the current is at 11 o clock reffered to the voltage.

Electrical interview question:Which type of A.C motor is used in the fan (ceiling fan, exhaust fan, padestal fan, bracket fan etc) which are find in the houses ?
Answer:Its Single Phase induction motor which mostly squirrel cage rotor and are capacitor start capacitor run.

Electrical Interview questions Part 3

Electrical interview question:why, when birds sit on transmission lines or current wires doesn't get shock?
Answer:Its true that if birds touch the single one line (phase or neutral) they don't get electrical shock... if birds touch 2 lines than the circuit is closed and they get electrical shock.. so if a human touch single one line(phase) then he doesn't get shock if he is in the air (not touching - standing on the ground if he is standing on the ground then touching the line (phase) he will get a shock because the ground on what we standing is like line (ground bed - like neutral)। and in the most of electric lines the neutral is grounded..so that means that human who touch the line closes the circuit between phase and neutral.

Electrical interview question:what is meant by armature reaction?
Answer:The effect of armature flu to main flux is called armature reaction. The armature flux may support main flux or opposes main flux.

Electrical interview question:what happen if we give 220 volts dc supply to d bulb r tube light?
Answer:Bulbs [devices] for AC are designed to operate such that it offers high impedance to AC supply. Normally they have low resistance. When DC supply is applied, due to low resistance, the current through lamp would be so high that it may damage the bulb element.

Electrical interview question:Which motor has high Starting Torque and Staring current DC motor, Induction motor or Synchronous motor?
Answer:DC Series motor has high starting torque. We can not start the Induction motor and Synchronous motors on load, but can not start the DC series motor without load.

Electrical interview question:what is ACSR cable and where we use it?
Answer:ACSR means Aluminium conductor steel reinforced, this conductor is used in transmission & distribution.

Electrical interview question:What is vaccum currcuit breaker.define with cause and where be use it Device?
Answer:A breaker is normally used to break a ciruit. while breaking the circuit, the contact terminals will be separated. At the time of seperation an air gap is formed in between the terminals. Due to existing current flow the air in the gap is ionised and results in the arc. various mediums are used to quench this arc in respective CB's. but in VCB the medium is vaccum gas. since the air in the CB is having vaccum pressure the arc formation is interrupted. VCB's can be used upto 11kv.

Electrical Interview questions Part 2

Electrical interview question:How tube light circuit is connected and how it works?
Answer:A choke is connected in one end of the tube light and a starter is in series with the circuit. When supply is provided ,the starter will interrupt the supply cycle of AC. Due to the sudden change of supply the chock will generate around 1000volts . This volt will capable of to break the electrons inside the tube to make electron flow. once the current passes through the tube the starter circuit will be out of part. now there is no change of supply causes choke voltage normalized and act as minimize the current.

Electrical interview question:whats is MARX CIRCUIT?
Answer:It is used with generators for charging a number of capacitor in parallel and discharging them in series.It is used when voltage required for testing is higher than the available.

Electrical interview question:What is encoder, how it function?
Answer:An encoder is a device used to change a signal (such as a bitstream) or data into a code. The code may serve any of a number of purposes such as compressing information for transmission or storage, encrypting or adding redundancies to the input code, or translating from one code to another. This is usually done by means of a programmed algorithm,especially if any part is digital, while most analog encoding is done with analog circuitry.

Electrical interview question:What are the advantages of speed control using thyristor?
Answer:Advantages :1. Fast Switching Characterstics than Mosfet, BJT, IGBT 2. Low cost 3. Higher Accurate.

Electrical interview question:Why Human body feel Electric shock ?? n in an Electric train during running , We did nt feel any Shock ? why?
Answer:Unfortunately our body is a pretty good conductor of electricity, The golden rule is Current takes the lowest resistant path if you have insulation to our feet as the circuit is not complete (wearing rubber footwear which doing some repairs is advisable as our footwear is a high resistance path not much current flows through our body).The electric train is well insulated from its electrical system.

Electrical interview question:what is the principle of motor?
Answer:Whenever a current carrying conductor is placed in an magnetic field it produce turning or twisting movemnt is called as torque.

Electrical Interview questions Part 1

Electrical interview question:What is electric traction?
Answer:Traction means using the electric power for traction system i.e. for railways,trams, trolleys etc. electric traction means use of the electricity for all these . now a days, magnetic traction is also used for bullet trains. basically dc motors are used for electric traction systems.

Electrical interview question:How can you start-up the 40w tube lite with 230v AC/DC without using any choke/Coil?
Answer:It's possible by means of Electronic choke.otherwise it's not possible to ionize the particles in tube. light, with normal voltage.

Electrical interview question:What is "pu" in electrical engineering?
Answer:Pu stands for per unit and this will be used in power system single line diagram there it is like a huge electrical circuit with no of componenes (generators, transformers, loads) with different ratings (in MVA and KV). To bring all the ratings into common platform we use pu concept in which, in general largest MVA and KV ratings of the component is considered as base values, then all other component ratings will get back into this basis.Those values are called as pu values. (p.u=actual value/base value).

Electrical interview question:Operation carried out in Thermal power station?
Answer:The water is obtained in the boiler and the coal is burnt so that steam is obtained this steam is allowed to hit the turbine , the turbine which is coupled with the generator generates the electricity

Electrical interview question:Why link is provided in neutral of an ac circuit and fuse in phase of ac circuit?
Answer:Link is provided at a Neutral common point in the circuit from which various connection are taken for the individual control circuit and so it is given in a link form to withstand high Amps. But in the case of Fuse in the Phase of AC circuit it is designed such that the fuse rating is calculated for the particular circuit (i.e load) only.So if any malfunction happen the fuse connected in the particular control circuit alone will blow off.

Electrical interview question: what is the diff. btwn. electronic regulator and ordinary rheostat regulator for fans?
Answer:The difference between the electronic and ordinary regulator is that in electronic reg. power losses are less because as we decrease the speed the electronic reg. give the power needed for that particular speed but in case of ordinary rheostat type reg. the power wastage is same for every speed and no power is saved.In electronic regulator triac is employed for speed control.by varying the firing angle speed is controlled but in rheostatic control resistance is decreased by steps to achieve speed control.

2010 Anna University Chennai B.E Electrical and Electronics Engineering EE-2204 Data structures and algorithm Question paper

B.E./B.Tech. DEGREE EXAMINATION, APRIL/MAY 2010
Third Semester

Electrical and Electronics Engineering
EE2204 — DATA STRUCTURES AND ALGORITHMS

(Common to Electronics and Instrumentation Engineering and Instrumentation and
Control Engineering)

(Regulation 2008)
Time: Three hours Maximum: 100 Marks

Answer ALL Questions
PART A — (10 × 2 = 20 Marks)

1. List out the areas in which data structures are applied extensively.
2. Convert the expression ((A+B)*C-(D-E)^(F +G)) to equivalent Prefix and Post fix notations.
3. How many different trees are possible with 10 nodes?
4. What is an almost complete binary tree?
5. In an AVL tree, at what condition the balancing is to be done?
6. What is the bucket size, when the overlapping and collision occur at same time?
7. Define graph.
8. What is a minimum spanning tree?
9. Define NP hard and NP complete.
10. What is meant by dynamic programming?

PART B — (5 × 16 = 80 Marks)

11. (a) (i) What is a linked list? Explain with suitable program segments any four operations of a linked list. (Marks 12)
(ii) Explain with a pseudo code how a linear queue could be converted into a circular queue. (Marks 4)
Or
(b) (i) What is a stack ADT? Write in detail about any three applications of stack. (Marks 11)
(ii) With a pseudo code explain how a node can inserted at a user specified position of a doubly linked list. (Marks 5)
12. (a) (i) Discuss the various representations of a binary tree in memory with suitable example. (Marks 8)
(ii) What are the basic operations that can be performed on a binary
tree? Explain each of them in detail with suitable example. (Marks 8)
Or
(b) (i) Give an algorithm to convert a general tree to binary tree. (Marks 8)
(ii) With an example, explain the algorithms of in order and post order traversals on a binary search tree. (Marks 8)
13. (a) What is an AVL tree? Explain the rotations of an AVL tree. (Marks 16)
Or
(b) (i) Explain the binary heap in detail. (Marks 8)
(ii) What is hashing? Explain any two methods to overcome collision problem of hashing. (Marks 8)
14. (a) (i) Explain Dijkstra's algorithm and solve the single source shortest path problem with an example. (Marks 12)
(ii) Illustrate with an example, the linked list representation of graph.(Marks 4)
Or
(b) (i) Write the procedures to perform the BFS and DFS search of a graph. (Marks 8)
(ii) Explain Prim's algorithm to construct a minimum spanning tree from an undirected graph. (Marks 8)
15. (a) (i) With an example, explain how will you measure the efficiency of an algorithm. (Marks 8)
(ii) Analyze the linear search algorithm with an example. (Marks 8)
Or
(b) Explain how the travelling salesman problem can be solved using greedy algorithm. (Marks 16)

2008 Anna University Chennai B.E Electrical and Electronics Engineering Ee2252 — power plant engineering Question paper

B.E./B.Tech. DEGREE EXAMINATION, APRIL/MAY 2010
Fourth Semester
Electrical and Electronics Engineering
EE2252 — POWER PLANT ENGINEERING
(Regulation 2008)

Time: Three hours: 100 Marks
Answer ALL Questions

PART A — (10 × 2 = 20 Marks)

1. Mention the various modern ash handling systems.
2. What are the factors affecting cooling of water in cooling tower?
3. Enumerate advantages and disadvantages of hydropower plants.
4. What is a surge tank?
5. What are the requirements of fission process?
6. What are the essential components of a nuclear reactor?
7. State the merits and demerits of closed cycle gas turbine over open cycle gas turbine power plant.
8. State the applications of diesel power plant.
9. What is a fuel cell?
10. What are the advantages and limitations of tidal power plant?

PART B — (5 × 16 = 80 Marks)

11. (a) Give the layout of a modern steam power plant and explain it briefly.[Marks 16]
Or
(b) How are cooling towers classified? Explain any one of them with a neat sketch.[Marks 16]

12. (a) Explain with a neat sketch a pumped storage power plant.[Marks 16]
Or
(b) What is the function of a hydraulic turbine? How are the turbines classified? Explain any one with a suitable sketch.[Marks 16]

13. (a) With the help of a sketch show all the important part of nuclear reactor. Describe briefly the functions of each part.[Marks 16]
Or
(b) Explain the following terms: (i) Fission of nuclear fuel (ii) Distribution of fission energy (iii) The chain reaction. [Marks 16]

14. (a) Discuss briefly the methods employed for improvement of thermal efficiency of open gas turbine power plant.[Marks 16]
Or
(b) List the essential components of a diesel power plant and explain them briefly.[Marks 16]

15. (a) Explain with a neat diagram of wind electric generating power plant.[Marks 16]
Or
(b) Describe open cycle MHD system with suitable sketch.[Marks 16]

2008 Anna University Chennai B.E Electrical and Electronics Engineering Ee2252 — power plant engineering qb Question paper

SUBJECT CODE / SUBJECT NAME: EE2252 / POWER PLANT ENGINEERING
SEMESTER: IV SEM-EEE (A & B SECTIONS)

PART A

1. What are the super critical boilers?
2. What do you understand by moderation?
3. What do you understand by the term equivalent evaporation?
4. What are the micro-hydel plants? Why are they important now-a-days?
5. What are fast breeder reactors?
6. Define maximum demand and load factor.
7. What are the fixed costs?
8. What are the applications of diesel power plants?
9. Why re-heaters and re-generators are used in power plants?
10. How the ash produced is important factor in the selection of thermal power plant?
11. What is water hammer?
12. What are the different fields where diesel power plant is essential?
13. What is super critical boiler? List down its merits.
14. Define fluidization.
15. What are the transfer equipments of coal handling at plant?
16. What is a 'CANDU' reactor?
17. What are the functions of steam condenser?
18. What is chain reaction?
19. Define the term "Breeding"?
20. How diesel plants are classified?


PART – B

1. Draw the layout of a coal based thermal power station of 200 MW capacity showing all necessary components and its function.
2. With neat sketch explain the working principle of the combined MHD- steam power plant.
3. Discuss the factors those go in the favour of nuclear power plant as compared to other types of types of power plants.
4. Draw a neat sketch of a La-Mont boiler and discuss its merits and de-merits over Benson boiler.
5. Explain the working principle of a fluidized bed combustion system with a neat sketch.
6. Explain the working principle of the electro static precipitator with neat sketch and give its outstanding features over other dust collectors.
7. Describe with the help of neat sketches the working principle of 'forced draft' and 'induced draft cooling towers.
8. Describe the boiling water reactor with the help of neat sketch and explain its chief characteristics.
9. Discuss the salient feature of the nuclear waste disposal.
10. Draw a neat diagram of in plant coal handling and indicate the equipment used at different stages.
11. Explain the advantages of pulverized coal burning.
12. Describe the automatic control of fuel and air supply systems in boiler
13. Discuss the various losses those are encountered in boilers .
14. What are the elements which contribute to the cost of the electricity, and how can the cost of power generation be reduced?
15. Determine the generating cost per unit of 80 MW power station with the following data Capital cost = Rs. 160×107
Annual cost of fuel = Rs.32×106
Annual wages & taxes = Rs.36×106
Interest &depreciation = 10% of capital cost.
Annual load factor = 45%
16. Sketch and explain the two pool tidal power plant .
17. Describe with a neat sketch the working of a solar thermal receiver system plant and enumerate the advantages and disadvantages of concentrating collectors over flat plat collectors.
18. With a neat sketch indicate the function of various parts of a nuclear reactor.
19. What are the different components of a nuclear power plant? Explain the working of a nuclear power plant.
20. Draw the layout of thermal power plant and explain the functions of each
component in it?
21. What are the factor considered for section of site of a hydro electric power plant?
22. Explain the construction and working principles of diesel power plant and state its
applications.
23. Explain the working principle of nuclear power plant.
24. Draw a neat line diagram of Benson boiler and discuss its relative merits and demerits.
25. Explain with neat sketch the principle of PFBC system.
26. What is meant by coal storage? Discuss the different methods used for coal storage at
plant?
27. Name the various methods of ash handling. Describe the pneumatic system of ash
handling.
28. Explain the working principles of electrostatic precipitator (ESP) and state its advantages and disadvantages.
29. Explain the operation of balanced draught with neat sketch.
30. Explain the different types of cooling towers used in thermal power plants?
31. Write short notes on I. Boiling Water Reactor. ii. Fast Breeder Reactor.
32. Explain the methods of governing of an impulse turbine
33. Explain with neat sketch the indirect gas cooled reactor.
34. Explain the essential components of diesel power plant with a neat layout.
35. Write short notes on the following for gas turbine
i. Reheating ii. Regeneration iii. Intercooling

2009 Anna University Chennai B.E Electrical and Electronics Engineering Ee2252 — power plant engineering qb Question paper

B.E./B.Tech. DEGREE EXAMINATION, APRIL/MAY 2010
Fourth Semester
Electrical and Electronics Engineering
EE2252 — POWER PLANT ENGINEERING
(Regulation 2008)

Time: Three hours
: 100 Marks
Answer ALL Questions

PART A — (10 × 2 = 20 Marks)

1. Mention the various modern ash handling systems.
2. What are the factors affecting cooling of water in cooling tower?
3. Enumerate advantages and disadvantages of hydropower plants.
4. What is a surge tank?
5. What are the requirements of fission process?
6. What are the essential components of a nuclear reactor?
7. State the merits and demerits of closed cycle gas turbine over open cycle gas turbine power plant.
8. State the applications of diesel power plant.
9. What is a fuel cell?
10. What are the advantages and limitations of tidal power plant?

PART B — (5 × 16 = 80 Marks)

11. (a) Give the layout of a modern steam power plant and explain it briefly.[Marks 16]
Or
(b) How are cooling towers classified? Explain any one of them with a neat sketch.[Marks 16]

12. (a) Explain with a neat sketch a pumped storage power plant.[Marks 16]
Or
(b) What is the function of a hydraulic turbine? How are the turbines classified? Explain any one with a suitable sketch.[Marks 16]

13. (a) With the help of a sketch show all the important part of nuclear reactor. Describe briefly the functions of each part.[Marks 16]
Or
(b) Explain the following terms: (i) Fission of nuclear fuel (ii) Distribution of fission energy (iii) The chain reaction. [Marks 16]

14. (a) Discuss briefly the methods employed for improvement of thermal efficiency of open gas turbine power plant.[Marks 16]
Or
(b) List the essential components of a diesel power plant and explain them briefly.[Marks 16]

15. (a) Explain with a neat diagram of wind electric generating power plant.[Marks 16]
Or
(b) Describe open cycle MHD system with suitable sketch.[Marks 16]