Most IMP Questions for Power Station Engineering [GTU Diploma Eng.]

Here is the MOST IMP QUESTION FOR POWER STATION ENGINEERING for Diploma Engineering Students from GTU

1). Explain the use of Induce Fan at Thermal Power Station.

2). Difference between Station Transformer and Unit Transformer.

3). Draw & Explain the Lay out of Power Station Control Room.

4). Describe the Ratings of Underground Cable.

5). How to find out the Ground Fault in Single Core Cable? Explain.

6). Explain the types of FACTS Controller.

7). Explain the Green House Effect.

8). Give the Essential & Desirable Condition for Parallel Operation of Transformers.

9). List out the Bus bar Arrangement and Explain the Bus section with Single bus

System.

10). Draw the Yd1, Yd11, Dy11 & Dy1 Connection Diagram and Vector Diagram of

Transformer.

11). Draw the Lay Out for Switchyard of Thermal Power Station.

12). Describe in Brief.

I) Condenser, II) Cooling Tower, III) Economizer, IV) Penstock,

V) Surge tower, VI) Reservoir,

VII) Spillage Gate.

13). Explain the Synchronization between the 3 phase Alternator with Infinite Bus bar.

14). Important Equipment in Thermal Power Station.

15). Advantages and Disadvantages of Hydro Power Station.

16). Explain Chain Reaction in Nuclear Power Station.

17). Types of Nuclear Reactor.

18). Schematic diagram and Selection of site for Nuclear Power Station.

19). Comparison between Thermal Power station and Nuclear Power Station.

20). Function of Switch Gear.

21). Explain Trickle and Float Charging.

22). Draw the Layout of switchyard.

23). Describe Fixed Field and Rotating Armature and Fixed armature and rotating field

type Alternator.

24). Explain Features and applications of Synchronous Motor.

25). Why the Synchronous Motor is used in Power System? Give Reason.

26). Give the Classification of Cables.

27). Explain the Method to prepare cable Joint.

28). Briefly Explain the Murray Loop Test.

29). Difference between Power and Control Cable.

30). Explain the methods of Termination of Cable in Power Station.

31). Give the uses of Power Cables.

32). Give the Advantages and Difficulties of Interconnection.

33). Give the Condition for Satisfactory Parallel Operation and Synchronizing of

Alternators.

34).What is Synchronizing Current, Power and Torque? Explain in Brief.

35).When the two Alternators is working in Parallel how the Sharing of Load between

them.

36).When the two Alternators are working in Parallel Explain

       I). Effect of Changing in Excitation.

       II). Effect of change in speed of one Alternator.

       III). Effect of unequal EMF.

37). Give the Conditions for Economical Loading of Alternator.

38). Give the Interconnected in Inphase and Quadrature Volatge Boost.

39). Condition for Maximum Power Transferred through Interconnected system.

40). Functions of Load Dispatch Center.

By Dhimant A. Patel [Facebook]

TRANSFORMERS - Insulating Materials

 TRANSFORMERS

Transformer Full Load Amps (FLA)

The Full Load Amps is the rated continuous current carrying capacity of a transformer at a referenced ambient temperature and allowable temperature rise.  Insulating materials are below for information.

The total temperature rise of an

 OA 65∞C transformer, at a maximum ambient temperature of 40∞C,

Is 120∞C.This does exceed the transformer insulation rating of 105∞C, and is allowed by ANSI.

The Full Load Amps label is located on the top decade at 1000 seconds. The Full Load Amps label is shown on the base

(Lowest KVA) rating of the transformer.

Table – Insulating Materials

Insulation        Maximum Temperature                         Insulating Materials Class

Y                              90∞C                                                       Cotton, silk, paper, wood, cellulose, fiber

Without impregnation or oil-immersion

                                                                                                 Class Y impregnated with natural resins,

A                              105∞C                                                     cellulose esters, insulating oils, etc.,

                                                                                                also laminated wood, varnished paper

Hybrid A               110∞C                                                     Insulter Insulation, Kraft paper with epoxy

Binders activated under pressure

E                              120∞C                                                     Synthetic-resin enamels, cotton and paper

Laminates with formaldehyde bonding

B                              130∞C                                                     Mica, glass fiber, asbestos, etc., with suitable

                                                                                                  bonding substance; built-up mica,glass fiber 

                                                                                                  and  asbestos laminates                                                                               

F                              155∞C                                                     The materials of Class B with more

Thermally-resistant bonding materials

H                             180∞C                                                     Glass-fiber and asbestos materials, and

Built-up mica, with appropriate Silicone resins

C                              >180∞C                                                  Mica, ceramics, glass, quartz, and asbestos

                                                                                               without binders or with silicone resins of super     
                                                                                                      thermal stability                                                                                

Hybrid H                  220∞C                                                     NOMEX insulation, varnish dipped

And vacuum pressure impregnated (VPI)

Transformer Through-Fault Damage Curve

Liquid-Immersed Transformers

Defines thermal and mechanical through-fault damage curves for liquid-immersed

Transformers,

“If fault current penetrates the limits of the thermal damage curve transformer insulation may be damaged. If fault current penetrates the limits of the mechanical damage curve cumulative mechanical damage may occur. The validity of these damage limit curves cannot be demonstrated by test, since the effects are progressive over the transformer lifetime. They are based principally on informed engineering judgment and favorable, historical field experience.”

Through-fault current is passing for the 2 to 1000 seconds.

Types of Maintenance

Types of Maintenance

1. Breakdown maintenance 

It means that people waits until equipment fails and repair it. Such a thing could be used when the equipment failure does not significantly affect the operation or production or generate any significant loss other than repair cost.

2. Preventive maintenance (1951) 

It is a daily maintenance ( cleaning, inspection, oiling and re-tightening ), design to retain the healthy condition of equipment and prevent failure through the prevention of deterioration, periodic inspection or equipment condition diagnosis, to measure deterioration. It is further divided into periodic maintenance and predictive maintenance. Just like human life is extended by preventive medicine, the equipment service life can be prolonged by doing preventive maintenance.

2a. Periodic maintenance (Time based maintenance - TBM) 

Time based maintenance consists of periodically inspecting, servicing and cleaning equipment and replacing parts to prevent sudden failure and process problems.

2b. Predictive maintenance 

This is a method in which the service life of important part is predicted based on inspection or diagnosis, in order to use the parts to the limit of their service life. Compared to periodic maintenance, predictive maintenance is condition based maintenance. It manages trend values, by measuring and analyzing data about deterioration and employs a surveillance system, designed to monitor conditions through an on-line system.

3. Corrective maintenance (1957) 

It improves equipment and its components so that preventive maintenance can be carried out reliably. Equipment with design weakness must be redesigned to improve reliability or improving maintainability

4. Maintenance prevention (1960) 

It indicates the design of a new equipment. Weakness of current machines are sufficiently studied ( on site information leading to failure prevention, easier maintenance and prevents of defects, safety and ease of manufacturing ) and are incorporated before commissioning a new equipment.

Types of Cooling towers

Based on type of Contact between air and water and the type of draft