General Description Of Pumped Storage Plants

In this article we will know about the pumped storage plants. We have also studied about the how pumped storage plants are use full for hydel power plant.

General Description Of Pumped Storage Plants

A pumped storage plant is a special type of plant meant to supply peak loads. During peak load period, water is drawn from the head water pond through the penstock and generates power for supplying the peak load. During the off-peak period, the same water is pumped back from the tail water pond to the head water pond so that this water may be used to generate energy during the next peak load period. Thus, the same water is used again and again and extra water is needed only to take care of evaporation and seepage. Generally the pumping of water from the tail water pond to the head water pond is done at night when loads are low. The plant generates energy for supplying peak loads during day time. The off peak pumping maintains the firm capacity of the pumped storage plant. The reservoir capacity should be such that the plant can supply peak load for 4 to 11 hours. A general arrangement of pumped storage plant .

Pumped Storage Plant Advantage, Application

The earlier pumped storage installations used a separate pumped of pumping the water back into the head water pond. A recent development is a reversible turbine pump. During peak loads, the turbine drives the alternator and the plant generates electrical energy. During low loads, the alternator runs as a motor and drives the turbine which now works as a pump for pumping the water into the head water pond. This arrangement reduces the capital cost of the plant. The power for driving the motor is taken from the system. 


Every pumped storage scheme reduces dual conversion of energy, the efficiency being around 60 to 70 percent. The fact that the energy gained from a pumped storage plant is always less than the energy input, should not obscure the fact that this apparent loss to the system is negligible when compared with the substantial savings in fuel which are made when these plants are used in a mixed system. The most obscures economies are in the replacement of standby thermal plants and in the fact that the existing thermal plants can be run with fewer and less rapid load changes.

Pumped Storage Plant Advantage, Application

Modern generation systems are a mixture of hydro, steam and nuclear power stations so that energy can be generated most economically. If hydro contribution is small, the steam and nuclear stations have to be of sufficiently large capacity. The steam and nuclear plants operate more economically when run continuously at or near full load. At the time of low loads the excess energy generated by stem and nuclear plants can be used for driving the motor of the pumped storage scheme. The pumped storage plant would in turn supply peak loads. Thus the capacity of the steam and nuclear plants need be only for supplying the base loads and hence much less than what it would be if they were to meet the whole demand. In addition the steam and nuclear plants can be worked at almost unity load factor which ensures their most economic operation. 

Advantages Of Pumped Storage Plant

Pumped storage plants have very important advantage. Some of these are:
Peak loads can be supplied at a lesser cost that that incurred when these loads are supplied by steam and nuclear plants.

(ii) Standby capacity is available on short notice. Power engineers in utilities having pumped storage installations have long realized the benefit of quick switching on and off capacity of these installations. Pumped storage plants need a starting time of only 2 to 3 seconds and can be loaded fully in about 15 seconds. In the event of an outage on a unit, a pumped storage plant can be called upon to meet the generation deficiency (occurring due to the outage) thus ensuring reliable supply and avoiding the necessary of load shedding.

(iii) The load factor of steam and nuclear plants is increased thus ensuring their efficient and economic operation.

(iv) Since the base loads plants needs not be used to supply peak loads. The forced and maintenance outages of these plants are likely to be reduced.

(v) In the event of an extra demand coming up suddenly on the system, these plants can be immediately switched on to meet this extra demand.

(vi) Because of their ability to take up loads in a very small time, the use of pumped storage plants reduces the spinning reserve requirement of the systems.

(vii) They can be used for load for frequency control.       

Types Of Pumped Storage Installation

Pumped storage plants offer many benefits. However their feasibility and economics should be critically evaluated at the planning stage. During the power system planning studies, three types of pumped storage installation can be considered: 

(i) High head, daily daily/weekly cycle, peaking plants close to the load center.

(ii) Low/medium head, seasonal cycle plants, far-away from load center (peaking or non-peaking types). 

(iii) Medium head, daily/weekly cycle peaking plants at an existing cascade of reservoirs.

Hence these are basic description of pumped storage plant if you will find any incorrect in above article you must comment below in comment box.

Classification of Hydro-electric power plant

In this article we will know about the classification of hydro-electric plants. We will know about various types of hydro electric plant.
 Classification of Hydro-electric power plant
 The classification of hydro-electric plant can be classified According to various steps 
 1. Flow of water
 Hydro plants can be classified, according to the extent of water regulation available, into following types:
According to flow of water , the classification of hydroelectric plant given below .

1. Run of river plant without poundage.

        2. Run off river with poundage

3.  Reservoir plants
Classification of hydro-electric plants, different type hydro-electric plant

1. Run of River plant Without poundage

 These plants are located such that they use water as it comes, without any poundage or storage. There is no control on flow of water. During period of high flows or low loads, water is wasted. During lean flow periods, the plant capacity is very low. High flows or low. As such these plants have very little firm capacity. In such sites, the water is mainly used for irrigation or navigation and power plant is only incidental. Such plants can be built at a considerably low cost but the head available and the amount of power generation are generally low. Their principal aim is to use whatever high flows, these plants can supply a substantial portion of base load. flow is available of energy generation and thus save coal that would otherwise be necessary for the steam plants. During the period of The generation capacity to be installed for such plants requires a careful consideration. The 72 MW plants of Louisville Gas and Elect. Company on Ohio River in U.S.A. is an example of this type of plant. it is main types of hydro-electric power plants.

2. Run off river plants with poundage. 

Poundage refers to storage at the plant to take care of hour to hour fluctuations in load on the station. Poundage increases the firm capacity of the station provided the floods do not raise the tail race water level thus reducing the effective water head and plant output. Such plants can serve as base load or peak load plants depending on the stream flow. When plenty of water is available, these plants can be used as base load plants. When stream flow decreases, these plants can be made to work as peak load plants. Show these two operated in operation of such plants. Thus these plants offer maximum conservation of coal when operated in conjunction with steam plants the 252 MW Hydro Plant and Safe Harbor Plant in U.S. A are example of this type of plants.

3. Reservoir plants.

 Most of the hydro-electric plants, everywhere in the world, belong to this category. When water is stored in a big reservoir behind a dam, it is possible to control the flow of water and use it most effectively. Storage increases the firm capacity of the plant. The plant can be used as a base load plant or as a peak load plant depending on the water stored in the reservoir, the rate of inflow and the system load. Grand Coulee of reservoir plants. In U S A, KRASNOYARKS plant in USSR and BHAKRA plant in India are notable examples of reservoir plants.. it is basic classification of hydro-electric power plants.

2. Classification of According to load

Classification of hydro-electric plants, different types of hydro-electric plant
  According to load, hydro plants can be classified as base load plants, peak load plants and pumped storage plant.

(1)    Base load plants.

 They feed the base load of the system. Thus they supply almost constant load throughout and operate on a high load factor. Base load plants are usually of large capacity. Run off river plants without poundage and reservoir plants are used as base load plants. For a plant to be used as base load plant, the unit cost of energy generated by the plant should be low.
it is also main types of hydro-electric plant.

(2)    Peak load plants.

 They are meant to supply the peak load of the system. Run off river of plants with poundage can be used as peak load plants during lean flow periods. Reservoir plants can, of course, be used as peak load plants also. Peak load plants have large seasonal storage. They store water during off-peak periods and are run during peak load periods. They operate at a low load factor. A special type of peak load plant is pumped storage plant.

(3)    Pumped storage plant.

 It is special type of plant meant to supply peak load. 

3. Classification of electric plant According to Head                      

Classification of Hydro-electric power plants, different types of hydro-electric plant

(1)    Low head plants.

   When head is less than 30 m, the plant is called a low plant. A dam or barrage across the river creates the necessary head. The power plant is located near the dam. And, therefore, no surge tank is need. Either one half of the barrage has regulating gates for discharge of surplus water while the plant is in front of the second half or the plant is constructed by the side of the river. Francis or Kaplan turbines are used. it is main types of hydro-electric plant

(2)    Medium head plants.

 The plants operating at head between 30 and 100 m. An open channel brings water from main reservoir to the fore-day from where pen stocks carry water to the turbines. Francis or Kaplan turbines are used.

(3)    High head plants. 

The plants operating at heads above 100m are generally  classified as high head plants. The civil works for these plants include reservoir, tunnel, surge tank and penstock. Generally Francis are used   for heads below 200m and penstock turbines for turbines for still higher heads.

If you will find any incorrect in above article you must comment below in comment box.

Solar Energy Collectors, Types of Solar Energy Collectors

In this article we will know about the solar energy collectors . we also know about the types of solar energy collectors.

Solar Energy Collectors

The first step in the solar energy utilization is the collection of this energy. This is done through collectors whose surfaces are designed for high absorptive and low emissivity.
Solar energy collectors, types of solar energy collector
these are following types of solar energy collectors. which is shown below.

1.  Flat Plate Collector.

 A flat collector consists of the following basic element:. it is very efficient type solar energy collector.
1. A flat plate upon which the short wave solar radiation falls and is absorbed and converted into heat energy.

2. An insulated container to eliminate or substantially reduce thermal losses from the collection system.

3. One or more plates of glass or transparent plastic to reduce the upward heat loss from the collection surface.

 4. Tubes or channels to circulate the liquid required to remove the heat energy from the collector to the strong tank.

A flat plate collector is shown in Fig. Solar radiation passes through the transparent cover and is absorbed by the collector plate. A fluid flowing in a passage in contact with the collector is heated and the heat from the fluid is extracted for use. The circulating pump keeps a continuous circulation of the fluid through collector and strong tank. In the storage tank, is working as heat ex changer, fluid heats water which is used for the desire purpose. The efficiency of the collection and conversion process depends on the heat loss to surroundings which in turn depends on the temperature at which the collectors work. The cover plate is transparent to incoming radiation but opaque to infra red radiation of the collector and thus reduces the heat losses. Treating the collector surface with special coating reduces the heat losses still further. These coating can be
 (1) particles of copper oxide about 1 u m in diameter, 
(2) semi- conductor like silica 
(3) layered coatings of calcium oxide and magnesium oxide. 

These coating have a high ratio of absorptive emissivity (about 10 to 15 or so) but are very expensive. Al though a variety may be used for the heat transfer in the collector flow channels. All practical system to date have used water or water ethylene glycerol solution, the letter additive being used primarily to avoid problem due to the freezing of liquid in the tube under subzero temperature conditions. it is very simple and less costly type solar energy collectors.
Solar energy collectors, types of solar energy collector
 Flat plate collector with honey comb structure. There is a growing interest in the use of honey comb cellular structure of various shapes. Some of which are shown in fig. 15.8.their excellent strength to weight ratio they have many application in aircraft and aerospace industries. Many materials like aluminum, glass, plastics etc. are used in the manufacture
Of these structures. It has found that collectors with honey comb cellular structures are more efficient and their use has been proposed in solar heat collectors. The process of heat transfer is a multi mode phenomenon and all the three modes, conduction, con- vection and radiation, should be considered in assessing the overall performance of any structure. In term of conduction affect the cellular surface. May be envisages as an extended surface used to increase the heat transfer area. In terms of convection effects, structure has been found to modify the convection transport from a heated body and in terms of radiation effects, they have been proposed for the creation of artificial black bodies and specials forms of terminal traps. An inclined flat plate solar collector with honey comb structure is shown in diagram.

2.  Concentrating Collectors

 In spite of the methods of reducing heat losses the maximum temperature at which a flat plate collector works is quite low, around 100 C IN summer and around 40c in winter. Concentrating collectors are more effective but very closely. Parabolic- at around can be   reflector used up to 30000 c However its direction has to be adjusted to follow the direction of sun rays.

A hemostat (b) is often used to reflect the radiation directly on the object to be heated. A combination of heliostat and parabolic reflector may also be used. The heliostat reflects the sun’s rays to the reflector. The heliostat can be adjusted to account for the change in sun’s position. it is very useful type solar energy collector .
Solar energy collectors, types of solar energy collector
The reflective surface of a heliostat usually consist of back silvered low iron glass or metalized plastic. These are fixed to light and mechanically stiff back up structures. The reflective surface is generally made up several small segments to allow better control of the flatness than a large single surface. These segments are also easily replaced in case of damage. The heliostats elements are mounted on that are fixed perpendicularly to a horizontals elevation members. Azimuth ally are elevations movements are made by separated drive mechanisms which typically consist of electric motor driven gears connected to the axes.

Helios tats have been found to be very suitable as collectors for solar power plants. Their cost is one of the key costs in the total cost of the plant. It is expected that better manufacturing processes and mass production will reduce their cost. hence it is main type of solar energy collector.


Non-convective solar ponds have been suggested for collecting solar energy on a large scale. A solar pond is a shallow body of water, about 1 metre deep containing dissolved salts to generate a stable density gradient (fresh water on top on denser salt water at bottom). Some of the incident solar energy entering the pond surface is absorbed throughout the depth and the remainder which penetrates the pond is absorbed at the black bottom. If the pond had only fresh water (or water of the same density) the lower layers would heat up, expand and rise to the surface. Because of convective maxing and heat loss at the surface only a small temperature rise in water would be realized. The convection can be eliminated by initially creating a sufficiently strong salt concentration gradient. In this case the thermal expansion in the bottom lower layers is insufficient to destabilize the pond. With convection nearly eliminated the heat loss from the lower layer is only by conduction. Because of its relatively low thermal conductivity water acts as insulator and permits temperatures up to 90%c to be developed in the bottom layers. solar pond is use full for solar energy collector to produce electricity,

Solar energy collectors, types of solar energy collector

One way to extract heat from solar ponds is to place pipes in the lower layers and circulate water through these pipes. A simpler and more efficient approach is to take advantage for stable density stratification and use method of selective withdrawal, a technique often use for water quality control in large reservoirs. A sink placed in stably stratified liquid withdraws the liquid from a thin horizontal layer, just as one would draw a single card from a deck. This flow is quite different from one that would occur if the density of water were the same throughout. The phenomenon of selective withdrawal provides means by which, firstly, the stable density gradient required in the upper insulating layer can be corrected and maintained at secondly the hot lower layer can be removed, passed through a heat ex changer and returned at a lower temperature to the bottom of the bottom of the pond. It is sometimes desirable to separate physically the bottom layer from the upper layer by a thin zone transparent partition, generally made of plastic.

The use of solar ponds has been suggested for salt production, space heating and power generation using organic fluid Rankin cycle engines which can operate relatively low source temperatures.  

Hence these are solar energy collector if you find any incorrect in above article you must comment below in comment box.

If you want to know more about the solar energy collectors you must watch this video.

Photo-Voltaic Cell Working

 In this article we will know about the photo-voltaic cell working and their application . we will know brief working of photo-voltaic cell.

Photo-Voltaic Cell working
It is possible to covert solar energy directly into electric energy by photo-voltaic process. The photo-voltaic effect is the generation of an EMF as a result of the absorption of ionizing radiation. Energy conversion devices which are used to convert sunlight to electricity by photo-voltaic effect are known as photo voltaic cells. Thus a solar cell is a transducer which converts the sun’s radiant energy directly into electricity and is basically a semi conductor diode capable of developing a voltage of 0.5 -1v and a current density of 20-40mA per 2cm depending on the materials used and the sun light conditions.

The photo –voltaic effect can be observed in nature in a variety of materials but the materials having the best performance in sun light are the semi conductors. When photons of the sun light are absorbed in a semi –conductor, they create free electrons (and holes) with higher energies than the electrons which provide the bonding in the crystal. Once these free electron holes to flow pairs are created, there must be an electric field to induce these higher energy electrons and holes to flow out of semi conduction to do useful work. In typical solar cell this is done by the use of p---n junction. It is known that an electric field exists across a p—n junction and this field sweeps the electrons in one direction and holes in the other. so these are basic working of photo-voltaic cell.

A typical solar cell is shown in diagram.  active area of solar cell is less than full front surface area because of the need to position opaque conductors on top the cell to collect the generated current. Practical top contact structure are generally in the form of comb to like grids so designed as to strike a balance between reduced active area and reduced series resistance brought about the increasing the contact coverage. An anti reflection coating is often employed to improve the coupling of light into the semi-conductor. The solar cell has to be encapsulated to protect it from atmospheric it is overall working of photo voltaic cell. for better know about photo-voltaic cell we must need to know about working of solar cell.

 Solar cell working

 Many types of solar cells have been proposed. The two types available commercially are single crystal silicon cells and cadmium sulfide/cumbrous sulfide cells. Single crystal silicon is the most highly developed material for photo voltaic conversion. The physical properties of single crystal silicon are well understood and the raw material is abundant. Single crystal silicon cells have efficiency around 10to 14 per been used for many years as power sources for space craft in sizes from a few watts to over 20KV per satellite. However they are still very costly and many attempts have been initiated in France, Japan, USA, West Germany etc. to reduce the cost.
    Hence these are photo-voltaic cell working if you will find any incorrect in above article you must comment below in comment box. thanks
If you want to know more about the photo voltaic cell working you must sea this video.

Conversion of Solar Energy into electrical Energy

In this article we will know that how solar energy converts into electrical energy, we will know about the conversion of solar energy into electric energy.


A solar power plants coverts solar energy into electrical energy. It consists of the following sub- systems.
  1. Solar energy collection system
  2. Thermal energy transfer system
  3. Thermal energy storage system
  4. Energy conversion system.

 Conversion of Solar Energy into electrical Energy 

A number of designs for the above sub- systems have been proposed. However only two types of solar power plants have been found to be feasible. These are known as Solar Farm or Distributed Collector system (DCS) AND Solar tower or central receiver system. The sub-system for the (DCS) having the following main features and details.
Conversion of Solar Energy into electrical Energy

1.  Solar energy collection system

The solar energy collection system for a DCS may consist of parabolic or parabolic dish collector.

A parabolic trough collector has an axial parabolic reflector at the focus of which is a heat receiver in the shape of tube. The trough is generally made of glass segments hot mould to shape and silvered on the back face. The segments are provided with a backing surface while may be made of metal of fiber glass or concrete. A number of troughs are combined to form a module. The heat receiver system, for troughs collector, consist of a metal tube inside a glass tube. The inner tube is generally painted black to aid heat absorption. The outer tube minimizes losses. Such a collector result in heat transfer medium temperature in the range of 150%c to 350%c and has an efficiency of about 25%c
Conversion of Solar Energy into electrical Energy
The dish of the parabolic dish collector is made of segments of synthetic material (e.g. fiber glass).small mirrored pieces of facets are bonded to the segments with a special adhesive. The receiver system for this collector has the shape of a sphere having a specially coated external. Surface Small diameter pipes run within the wall of the receiver and carry the heat transfer medium. This collector system result in temperature of 200%C 500%C in the heat transfer medium. its very use full for conversion of solar energy into electrical energy.

2. Thermal energy transfer system.

This transfers the heat energy from the receiver to the turbine. Water, sodium, salts gases (air, helium. Hydrogen, ammonia) can be used as heat transfer media.
When the transfer medium is water, steam can be generated directly in the receiver. When the medium is gas, a gas turbine has to be used. When sodium and salts are used for heat transfer, secondary heat transfer circuit is also necessary and the cost is higher. However, when these media are used higher working temperature and pressures can and the heat transfer coefficients are is first step of conversion of solar energy into electrical energy.

  3. Thermal energy storage system.

 Solar energy is not available all the time. If a solar power plant is working as an isolated plant and is the only source of supply for an area, some from heat energy storage is necessary. One form of storage can be a pressure vessel storing water and steam at a temperature near the boiling point. When steam is extracted, both temperature and pressure in the vessel decrease causing conversion of water into steam. In this storage system into can run only on part load. The thermal storage system can system can also consist of sodium or molten salt. When this storage system is used, two transfer circuits are necessary. However the turbine can operate at full load from such a storage system. it provide continuity of conversion of solar energy into electrical energy.

4.  Energy conversion system.  

 The energy conversion system converts heat energy to electrical energy. The solar heat from the receiver or storage converts feed water into steam which is fed to turbine. The turbine drives the generator. Steam is condensed in the condenser and water return to the boiler for reuse as feed water .The heat of the cooling water of the condenser may be used for subsidiary purposes.  In various image shows the basic element of a distributed collector system solar power plant. in this type solar energy convert into electrical energy.


Considerable attention has been given, during the last few years, to solar power tower concept for conversion of solar energy to electrical energy. In this method a central receiver situated at the top of a tower receivers concentrated solar energy reflected from a field of mirrors (or hemostats) which are arranged in some regular manner around the base of a tower. This collection system simulates a very large parabolic on ground. The solar energy collected by the receiver is absorbed by a receiver coolant which gets heated up. The heat of this finally transferred to feed water in a boiler. The feed water gets converted into a steam which drives the turbine. The receiver coolant can be water, liquid sodium, molten, salts or gases like helium or air.
. The complete system consists of a number of sub-systems. The sub-systems are (1) hemostat or collection sub-system (2) receiver/tower sub-system (3) electric power generation sub-system consisting of steam turbine and generator (4) cooling tower sub-system for cooling the water used in condenser for condenser steam (5) master control sub-system for controlling the whole system (not shown in the figure). (6) Storage sub-system. Some form of storage is needed to maintain plant output at a constant level despite solar insulation variations. solar power tower improve efficiency of conversion of solar energy into electrical energy.

Solar power tower technology is about 40 years old. A 10 mw pilot plant was commissioned in 1981 in California (USA). Considerable design and hard hardware expertise exists in USA for using this concept. Many economic, simulation and optimization studies have been undertaken. The results of economic studies are quite encouraging. The environmental problems are minimal and the concept seems to offer lasting solution of energy shortage problem. 

hence these are some processes which is use in conversion of solar energy into electrical energy if you will find any incorrect in above article you must comment below in comment box.

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Power Plant Economics study

In this article we will know about the power plant economics. Which means we will study about which type resources are required for start a new power plant.

Power Plant Economics


It is most important factor of power plant economics.
The generation cost per kWh of energy depends. On the cost covering the purpose, installation and erection of equipment, cost of fuel, labor, repair etc, The generation cost can be divided into fixed cost i.e. the cost which depends on the extent of plants investment and financial rates and remain a fixed one irrespective of the amount of energy generated and operating cost which includes the expenditure for fuel, labor, supervision etc. The operating costs of a plant are generally variable in magnitude and depend on the amount of energy produced.


Capital cost of plant is also a main factor to know about the power plant economics.
The capital cost of a plant includes the preliminary cost, cost of land and other real estate, cost of design and planning, cost of building and equipment, cost of transportation, erection and installation of equipment and overheads etc. the cost of a steam plant located near a river where adequate supply of cooling water is available would be less than that of one in which cooling towers or ponds are needed for cooling water.
Power Plant Economics study, study of power plant economics.
In addition to the costs mentioned above, the capital cost of a hydro-electric plant includes the costs of dam, earth work, excavation,rail head,highways and other civil works and compensation to property owners whose lands would be submerged in the reservoir.
The capitals costs of plants vary very widely even for similar types of plants and depend to a large extent on the market conditions. The range of cost for hydro plants is greater than that for steam plants, the reason being that in case of steam plants, only about 15 percent of the cost is influenced by topographical condition. Whereas in the case of hydro-electric plants, around 75 percent of the cost is affected by these conditions.
In general a large plant costs less per KW of installed capacity than a small one. A plant having a small number of large sexed units costs less than a plant of the same total capacity but having a large number of small sized units. Roughly the capital costs are around Rs. 3000 to 35000 per KW for diesel, gas and steam plants, Rs 4000 to 60000 per KW for hydro-electric plants and Rs. 15000 to 60000 per KW for nuclear plants.

3. Annual fixed cost of power plant

In this topic we will know about total fixed cost in one year of any power plant. We will discuss about the various type fixed cost, which is essential to know for understand of power plant economics.
Components Of power plant
The annual fixed cost of a plant consists of interest, taxes, insurance, depreciation, managerial and general maintenance cost and rate of return.

A. Interest, taxes and insurance.

The capital for setting up the plant may be provided by the government (or the private owner) or acquired through loan form financial institution or acquired by the sale of stuck or bonds or both. The annual interest and dividend gave to be included in the total cost of service. The utility may have to pay various taxes to town, state and federal authorities. However, only the taxes which are a function of the capital investment should be included in the fixed costs and the other taxes should be included in the operating costs.
Every well managed utility has to incur expenditure on insurance against accident to equipment and personnel.  The list of risk and insurance is usually very long. Example, fire, flood, hail, earthquake explosion public liability, workmen compensation etc. the insurance may be obtained from insurance companies or if the enterprise is very big. It may be self-insured. This is done by setting aside a reserve fund, out of earnings, every year. Such an insurance fund is quite district and separate from the depreciation fund.

B. depreciation of power plant

Every equipment deteriorates or depreciates due to wear and tear, corrosion. Weathering etc. in addition, the equipment may become inadequate due to increase in demand or become absolute and may need replacement by a modern one.
It is necessary for the financial stability and safety that the capital of an enterprise must remain intact. When a plant becomes useless, funds must be available to replace it. The methods for calculating depreciation are discussed in section 3.7.

C. Managerial and general maintenance costs.

part of total wage bill of a power plant is constant irrespective of the amount of energy. These costs are proportional to the size of the plant and the equipment and should be included in fixed costs.

D. Rate of return of power plant

An undertaking can be successful only if it earns profit. It is a private limited company and has floated shares or bonds, it must pay a good dividend so that the value of the shares may be high and the undertaking may be successful. Therefore, a certain rate of return on investment should be taken into account in calculating the annual fixed costs.

4. Operating cost or production cost

The operation of a plant means expenses which vary with the extent of operation or the amount of energy produced. such expenses are included in the annual operating costs, the items which constitute operating costs are:  fuel , operating labor, maintenance costs and supplies. in steam, diesel and gas plants,the operating costs form a major portion of total annual cost whereas in hydro, nuclear and solar plants,the fixed costs overshadow the small operating costs. 

(a)      Fuel. 

This is largest item of expense in thermal, diesel and gas turbine stations. The fuel may be in the form of coal, oil, natural gas, wood scrap etc. The cost of fuel depends on the type of fuel, calorific value, availability and freight rates. The annual fuel cost of a station depends on the amount of energy produced, the efficiency of the plant and the unit price of fuel. The fuel cost of station can be anticipated if (i) a realistic load model is known for each future week or month in the planning period (ii) the units are committed to supply load in a manner that reflects actual operating procedures and conditions.

(b)     Operating labor 

 The operation of a plant needs staff and labor. In a steam plant labor is needed for unloading and storing of fuel, disposal of refuse, operation of boiler, prime mover etc. The increasing application of automatic equipment and the increase in unit sizes have reduced the number of men required to operate a plant by a considerable amount. Hydro plant and diesel plants need less labor than steam plants.

(c)    Maintenance cost. of power plant

 Every plant needs preventive maintenance (inspection cleaning repair, overhauling etc.) to keep it in good condition. The maintenance cost can be further subdivided into the cost of material required for maintenance and cost of labor. To estimate the maintenance cost of proposed plant, the information from a similar plant in an analogous situation can be used.

(d)    Supplies. 

This item includes the cost of water for makes up, cooling purposes and general use, lubricating oil and other consumable materials.
Hence this is power plant economics study if you have find any incorrect in above article you must comment below in comment box. 

Difference between Asynchronous and Synchronous counter

In this article we will know about the difference between asynchronous and synchronous counter. We will also study that what is counter basically and their working.

Difference between Asynchronous and Synchronous counter, Synchronous and asynchronous counter

working of synchronous and asynchronous counter

Counter may be asynchronous counter or synchronous counter. A synchronous counter is also named as ripple counter. In asynchronous counter, all the flip-flips are not clocked simultaneously, whereas in a synchronous counter all the flip-flops have some clock. Comparison of synchronous and asynchronous is given table. 
Difference between Asynchronous and synchronous counter

  Asynchronous counter
  Synchronous counter
1. In case of asynchronous counter, all the flip-flops are not clocked simultaneously.
In case of synchronous counter, all the flip-flops are clocked simultaneously.
2. In the case of asynchronous counter, the output of first flip-flop drives the clock for second flip-flop, the output of second drives the third and so on.
In case of synchronous counter , there is no interconnection between output of one flip-flop and clock of next flip-flop,
3. The settling time of asynchronous counter is cumulative sum of individual flip-flops.
The settling time of synchronous counter is equal to highest settling time of all flip-flops. theses are basic difference between asynchronous and synchronous counter.
4. Asynchronous counter is known as serial counter
Synchronous counter is known as parallel counter.
5.Its design and implementation is very simple.
Synchronous counter design and implementation becomes tedious and complex as the number of states increases.
6. Asynchronous counter is slow in speed as compare of synchronous counter.
Synchronous counter is faster in speed as compare to asynchronous counter.

Hence these are some difference between asynchronous counter and synchronous counter. If you will find any incorrect in above article you must comment in comment box.

If you want to know more about difference between synchronous counter and asynchronous counter you must watch this video.

Digital electronics interview questions

In this article we will learn about the digital electronics interview question. Which is mainly asked in various interview.

Digital electronics interview questions, basic digital electronic question

Digital electronics interview questions

Digital electronics interview questions, basic digital electronic question

1. What is meant by radix (or base) of a number system?

Radix or base of number system is the number of digits or distinct symbols it uses to represent various numbers.

2. What is weighted code? Give one example.

In a weighted code the value of a digit in a 4-bit depends on its position such as in BCD code.

3. What is non-weighted code?

In a non-weighted code, no definite weights are assigned to the four digit positions such as in excess-3 code.

4. What is difference between LSB and MSB?

The right most bit of a binary number is called least-significant bit (LSB) while the left most bit of a binary number is known as most-significant bit (MSB).

5. What is meant by BCD code?

BCD code is a decimal system with each digit encoded in its binary equivalent of 4 bits.

6. What is excess-3 code |?

Excess-3 code is derived from the natural BCD code by adding 3(0011) to each coded number.

7. Why hexadecimal code is widely used in digital system?

It is very convenient to enter binary data in a digital system using hex code.

8. What is the difference between binary code and BCD?

BCD is not a number system like binary. It is a decimal system with each decimal digit encoded in its binary equivalent. A straight binary code takes the complete decimal number and represents it in binary while the BCD code converts each decimal digit to binary individually. It is most useful digital electronics interview question because mostly come in interview exam.

9. Explain the use of excess-3 code.

The key feature of the excess-3 code is that it is self-complementing code. It means that 1’s complement of the coded number yields 9’s complement of the number itself. The self-complementing property makes the excess-3 code useful in some arithmetic operations, because subtraction can be performed using9’s complement method and 1’s complement can be easily produced with digital logic circuits by simply inverting each bit.

10. What are the advantages of gray code?

In Gray code, if we go from any one decimal number to the next, only one bit of the Gray close changes. Because of this feature, an amount of switching is minimized and the reliability of the switching systems is improved. Advantage of gray code is main interview question of digital electronic.

11. What is an alphanumeric code?

The codes used for representing letters of alphabet. Punctuation marks and other special characters along with numbers are called alphanumeric codes.

12. What is Boolean algebra?

Boolean algebra is a mathematical system of logic in which truth functions are expressed as symbols are manipulated to arrive at conclusion. It is also maximum asked in digital electronics interview question.

13. What are the basic logic elements?

Basic logic elements are NOT gate, AND gare, OR gate and the flip-flop.

14. What is a truth table?

Truth table is a table that gives outputs for all possible combinations of inputs to a logic circuit.

15. Define the positive logic and negative logic?

If the higher of the two voltages represents a 1 and the lower voltage represents a 0 , the logic is called a positive logic. On the other hand, if the lower voltage represents a 1 and the higher voltage a 0, we have a negative logic.

16. What is pulse logic system?

A logic system in which a bit is recognized by the presence or absence of a pulse is called a pulse or dynamic logic system.

17. What is an inverter?

An inverter is logic gate whose output is the inverse or complement of its is main equipment of digital electronic system which is asked in interview.

18. What is the specialty of NAND and NOR gates?

The specialty of NAND and NOR gates is that they are universal gates and can perform all the basic logical operations.

19. What is associate law?

Associate law is a law of addition and multiplication and according to this law grouping of the variables in the ORing or ANDing of several variables is immaterial and the results obtained are the same.

20. what is minterm ?.

A term containing literals corresponding to all the variables in ANDed terms ORed terms ANDed together.

21. What is maxterm in digital electronic system?

A term containing literals corresponding to all the variables in ORed from is known as a maxterm.

22. what is the difference between canonical form and standard form?

In Canonical form , a Boolean function is expressed as sum of minterms or product of maxterms and is obtained by  reading a function from the truth table. Canonical forms may or may not contain the least numbers of literals because by definition, each maxterm or minterm must contain all variables, complemented or un complemented. In standard form, the terms of function may contain one, two or any number of literals. Standard form is expressed as sum products or product of sums.

23. what is the use of De Morgan’s theorem.?

De Morgan’s theorems are extremely useful in simplification of Boolean expressions in which a sum or product of variables is inverted.

24. What is karnaugh map?

The limitation of karnaughs map is that beyond 6 variables it becomes very cumbersome and so it is generally used up to 6 variables.

25. What is the use of a karnaugh map?

Karnaugh map is used for simplification and manipulation of Boolean expressions.

26. What is a half-adder?

A logic circuit, that can add two 1-bit numbers and produce outputs for sum and carry, is called a half adder.

27. What is full-adder?.

A binary adder, which can add two 1-bit binary numbers along with a carry bit a produces outputs for sum and carry is called a full-adder.

28. What is logic signal required to inhibit a NAND gate and what is its output when inhibited? 

Logic 0 is the logic signal required to inhibit a NAND gate and 1 is its output, irrespective of all other inputs, when inhibited.

29. What is multiplexing?

Multiplexing is an operation performed with digital logic circuits several lines into single lines into a single line in a specified sequence.

30. What is an encoder?

An encoder is a logic circuit that produces coded binary inputs from encoded inputs.

31. What is a DE multiplexer?

DE multiplexer is a logic circuit that accepts one data input and distributes it over several is also most important interview question of digital electronics.

32. What is a decoder?

Decoder is a logic circuit that decodes from binary to octal decimal, hexadecimal, or any other code such as 7-segment circuit etc.

33. What is sequential circuit?

Sequential logic circuit is that circuit in which outputs of the circuit remain in their state, until instructed to change it. In other words sequential logic circuit may be defined as that logic circuit whose outputs are determined by the sequence in which input signal are applied.

34. What is a flip-flop?

A flip-flop is a basic memory element that is made of an assembly of logic gates and is used to store 1-bit of information. Flip flop is main subject of digital electronics which are mostly asked in interview.

35. What is a latch?

It is a D-type of flip-flop and stores one bit of data.

36. What is an excitation table?

Excitation table gives information about what should be the flip-flop inputs if the outputs are specified before and after the clock pulses.

37. What is a state table?

State table consists of complete information about present state, next state, and out puts of a sequential circuit.

38. What is meant by a counter?

Counter is a digital circuit which is used to count pulses and give the output in the binary form.  These are also main interview question of digital electrics.

39. What is difference between synchronous and asynchronous counters?

In a synchronous counter all the flip-flops get clocked simultaneously where as in an asynchronous counter the output of one flip-flop drives another flip-flop.

40. What is a ripple counter?

When the output of one flip flop drives another flip flop, the counter is called a ripple counter.

Hence these are some digital electronics interview questions. If you have any query in theses question you must comment below in comment box.

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