Explain the choice of size and number of generator units in a power plant. 

1 Answer

Answer :

Selection of Size and Number of Generating Units: 

1. The size/rating and number of generating units in such way that they approximately match with the load curve/load duration curve as closely as possible. 

2. In order to calculate the size of the units, the station auxiliary load should be taken in to account. 

3. Also the transmission line losses should be considered. It can be approximately taken as 20 % of the consumer load. 

4. The future demand and expansion should also be considered as the load on the station always increases. 

5. The plant must have some reverse capacity at least 15-20 % more than M.D. under abnormal conditions. 

6. Select size/rating of generating units in such way that reliability to maintain supply will be more. 

7. Select size/rating of generating units in such way that the plant capacity factor, load factor diversity factor, plant use factor will be more. 

8. Select size/rating of generating units in such way that unit almost run at full load or at load which gives maximum efficiency. 

9. Select size/rating of generating units in such way that power generation will be economical. 10. Initial and operating cost also to be taken in to account 

11. Space required also to be considered. 

12. The minimum number of units should be two. 

13. As far as possible, the units of equal capacities are selected which will have following advantages. i) The parts can be interchanged. ii) The maintenance will be easier. iii) The working time of each plant regulated. iv)The spare parts required to be stored are less. 

14. While selecting the size/rating and number of generating units there are two options i) To select single generating unit of large capacity ii) To select more numbers of small capacity generating unit either of same ratings or different ratings. Both options have its own advantages and disadvantages. 

15. In summary, Load on the power system is variable where reliability of supply is important so it is neither practicable nor economical to use a single unit of large capacity. But, if power plant is connected to grid system then generating unit of higher capacity can be installed.

Related questions

Description : What is the choice of size and number of generator units in interconnected power system?

Last Answer : Choice of Size and Number of Generating Units: 1. The size/rating and number of generating units in such way that they approximately match with the load curve as closely as possible. 2. In ... , if power plant is connected to grid system then generating unit of higher capacity can be installed.

Description : With a neat diagram explain doubly fed induction generator (DFIG). 

Last Answer : Diagram of Doubly fed induction generator (DFIG):  Explanation :-  DFIG can feed power through the stator as well as rotor to the grid. The stator is directly connected to the fixed frequency ... voltage is 690 V AC. So it must be step up to 33 KV to connect to power grid.  

Description : Explain Squirrel Cage Induction Generator (SCIG) and also draw a diagram. 

Last Answer : Explanation (Operation):- In this system gearbox is used to increase the speed of high speed shaft as per design. IG require reactive power for excitation. Rotor of SCIG is ... , variable voltage output of the generator into the fixed frequency, fixed voltage output required for grid. 

Description : For optimum generator scheduling for different power plants, the minimum fuel cost is obtained when

Last Answer : For optimum generator scheduling for different power plants, the minimum fuel cost is obtained when The incremental fuel cost of each plant multiplied by the penalty factor is the same

Description : In a synchronous generator delivering lagging power factor load  (1) the excitation emf leads terminal voltage by the power angle (2) the excitation emf lags terminal voltage by the power angle (3) ... by the power factor angle (4) excitation emf lags the terminal voltage by the power factor angle

Last Answer : In a synchronous generator delivering lagging power factor load the excitation emf leads terminal voltage by the power angle

Description : A large AC generator, supplying power to an infinite bus, has a sudden short-circuit occurring at its terminals. Assuming the prime mover input and the voltage behind the transient reactance to remain constant immediately after the fault, acceleration of the generator rotor is

Last Answer : A large AC generator, supplying power to an infinite bus, has a sudden short-circuit occurring at its terminals. Assuming the prime mover input and the voltage behind the transient reactance ... , acceleration of the generator rotor is inversely proportional to the moment of inertia of the machine

Description : The armature reaction in a synchronous generator supplying leading power factor load is (A) magnetizing (B) demagnetizing (C) demagnetizing and cross-magnetizing (D) magnetizing and cross-magnetizing

Last Answer : The armature reaction in a synchronous generator supplying leading power factor load is magnetizing and cross-magnetizing

Description : Briefly explain how an electrical generator converts mechanical energy into electrical energy.

Last Answer : Working principle of DC generator: * Working principle of DC generator is the principle of dynamically induced emf or electromagnetic induction. * According to this principle, when flux is cut by a conductor, an ... , the flux is cut by the armature winding and an emf is dynamically induced in it. 

Description : Explain how sinusoidal AC voltage is generated by using simple one loop generator.

Last Answer : An electric current produced by means of electrical machine is known as generator which converts mechanical energy into electrical energy. When conductor cuts the magnetic flux, emf induced in it. (Faraday' ... upon position of armature. The nature of emf is alternating as shown by the waveform. 

Last Answer : In a D.C. generator the number of mechanical degrees and electrical degrees will be the same when number of poles is 2.

Description : For a D.C. generator when the number of poles and the number of armature conductors is fixed, then which winding will give the higher e.m.f. ?

Last Answer : Wave winding

Description : Owners manual for an Eastern Steel generator?

Last Answer : If it is this one it has been reviewed on Amazon. Perhaps one of the reviewers could help?

Description : How To Make Cascade Generator

Last Answer : This cascade engine was invented in the 1930's by a 17-year old amateur experimenter who was simply trying to make a new version of the old Fizeau's condenser. Instead, he discovered a ... a gravitic pressure wave in the surrounding space. Higher voltage and pulse rate generates greater thrust.

Description : How To Make A Simple Dry Ice Fog Generator

Last Answer : You can make a very simple, yet effective fog generator for use with an air cannon, or for use at parties or with laser experiments. The fog generator is made from an ice chest. I use an inexpensive ... hose. That's it! When the fog generation diminishes, recharge with hot water and/or more dry ice.

Description : How Does a Van de Graaff Generator Work?

Last Answer : How Does a Van de Graaff Generator Work? The Van De Graaff generator is an energy source. It could produce up to 20 million volts in charge. It is used for various physics experiments. Examples would be ... . This is a theory affected by so many factors. Time will be the sole judge of that theory.

Description : How to Build a Wind Generator

Last Answer : How to Build a Wind Generator Energy consumption is a serious concern for many people, especially those who are conscious of carbon emissions and global warming. Alternative energy sources ... have an economical, sustainable, and environmentally-friendly solution to your power and energy needs.

Description : How to Build a Hydro Generator

Last Answer : How to Build a Hydro Generator How to Build a Hydro Generator Hydroelectricity generators are capable of producing electricity using hydropower. It is a form of convertible energy. Small hydro ... of electricity to homes and business centers thousands of kilometers away through a network of wires.

Description : How to choose a diesel generator?

Last Answer : Diesel generators are widely used in various fields as the main or safety source of electricity. Stability in this case plays one of the most important roles, therefore, the choice of a ... purpose of the device, the most convenient and versatile are generators with an automatic control mode.

Description : What is the difference between Generator and Motor?

Last Answer : If a rotating machine delivers a power as output it is called generator. If power required to rotate a machine it is called motor.

Description : applications of : (1) Function generator   (2) Video pattern generator (3) AF signal generator and (4) Pulse generator. 

Last Answer : 1) Function generator: i) As trouble shooting tool to different analog and digital circuits. ii) As a source of alignment of different receiver. iii) If rise time of square wave is ... trigger output, pulses are available. iii) The generator can be operated as free running generator.

Description : AC generator

Last Answer : A.C power can be generated as a single phase or as a balanced poly-phase system. However, it was found that 3-phase power generation at 50 Hz will be economical and most suitable. Present day three phase generators ... has uniform air gap (figure 2.1(b)) and used when speed is high. 

Description : State the function of commutator in DC generator and name the material used for commutator.

Last Answer : Function of Commutator: Commutator converts AC induced in armature winding into DC for external load. Material: i) Commutator segments are made up of Copper. ii) Commutator segments are insulated from each other by Mica.

Description : List out any four salient features of hydro generator.

Last Answer : Following are the salient features of a Hydro Generator (alternator):  It is 3-ph hydro generator (alternator). It is robust in construction. A separate excitation is given to ... & under frequency protection, 5. Over temperature protection are main protections provided to generator.

Description : List any four applications of function generator.

Last Answer : Applications of function generator: 1. To test the bandwidth of audio frequency amplifier. 2. Used for troubleshooting of different analog and digital circuits. 3. Acts as source for alignment of receivers 4. For generation of different waves.

Description : Draw a labeled block diagram of sine wave generator and state function of each block. 

Last Answer : Function Generator:  This instrument can deliver sine, triangular & square waves with frequency range of 0.01 Hz to 100 kHz.  The frequency control network is governed by a frequency ... voltage reaches a predetermined level on the negative slope of the integrator's output voltage.

Description : Draw block diagram of function generator. Write applications of function generator.

Last Answer : Applications of Function Generator: 1. To test the bandwidth of audio frequency amplifier 2. It can produce sine wave, triangle wave, saw tooth wave, even arbitrary waveform. 3. ... for troubleshooting of different analog and digital circuits 7. Acts as source for alignment of receivers.

Description : A 200 V DC machine supplies 20 A at 200 V as a generator. The armature resistance is 0.2 Ohm. If the machine is now operated as a motor at same terminal voltage and current but with the flux increased by 10%, the ratio of motor speed to generator speed is

Last Answer : A 200 V DC machine supplies 20 A at 200 V as a generator. The armature resistance is 0.2 Ohm. If the machine is now operated as a motor at same terminal voltage and current but with the flux increased by 10%, the ratio of motor speed to generator speed is 0.87

Description : A _________ is used to measure the stator % winding temperature of the generator.  (A) Thermocouple (B) Pyrometer (C) Resistance thermometer (D) Thermometer

Last Answer : A Resistance thermometer is used to measure the stator % winding temperature of the generator. 

Description : The fall in speed of a dc generator due to increase in load can be corrected by  (1) cooling the armature.. (2) increasing the excitation. (3) reducing the load voltage. (4) increasing the input to the prime mover

Last Answer : It   can  be  corrected  by  increasing  the  input  to  the  prime  mover.

Description : The eddy current loss in a dc generator is 400 W at 40 Hz frequency of reversal and constant flux density. When frequency is increased to 50 Hz., eddy current loss is :  (A) 256 W (B) 320 W (C) 500 W (D) 625 W

Last Answer : The eddy current loss in a dc generator is 400 W at 40 Hz frequency of reversal and constant flux density. When frequency is increased to 50 Hz., eddy current loss is : 625 W

Description : In a synchronous generator if the excitation increased from a low value to normal value, with a fixed load  (A) The armature current increases and the power factor decreases  (B) The armature ... but is lagging  (D) The armature current decreases and the power factor increases and is leading

Last Answer : In a synchronous generator if the excitation increased from a low value to normal value, with a fixed load The armature current decreases and the power factor increases and is leading

Description : In a DC generator the windings of interpoles are connected :  (A) in series with main field winding, to create a pole,of same polarity as the main pole ahead in the direction of rotation.  ... winding, to create a pole of opposite polarity as the main pole ahead in the direction of rotation.

Last Answer : In a DC generator the windings of interpoles are connected :  in series with the armature winding, to create a pole of same polarity as the main pole ahead in the direction of rotation. 

Description : The terminal characteristics of a dc generator suitable for electric welders is (A) separately excited generator (B) shunt generator (C) series generator (D) differentially compounded generator

Last Answer : The terminal characteristics of a dc generator suitable for electric welders is differentially compounded generator

Last Answer : The critical resistance of the D.C. generator is the resistance of field.

Last Answer : Armature reaction in a generator results in demagnetisation of leading pole tip and magnetisation of trailing pole tip.

Description : If residual magnetism is present in a D.C. generator, the induced e.m.f. at zero speed will be?

Last Answer : If residual magnetism is present in a D.C. generator, the induced e.m.f. at zero speed will be zero.

Last Answer : In a separately excited generator supplying rated load the armature reaction is always present.

Last Answer : A 220 V D.C. generator is run at full speed without any excitation. The open circuit voltage will be about 2 V.

Description : A sinusoidal voltage of 5 Hz is applied to the field of a shunt generator. The armature voltage wave?

Last Answer : A sinusoidal voltage of 5 Hz is applied to the field of a shunt generator. The armature voltage wave will be of 5 Hz.

Last Answer : In a level compounded D.C. generator, full load terminal voltage is equal to no-load terminal voltage.

Last Answer : In over compounded generator, full load terminal voltage is more than no load terminal voltage.

Last Answer : In case of a flat compounded generator voltage remains constant irrespective of the load.

Last Answer : An exciter for a turbo generator is a shunt generator.

Last Answer : In a D.C. generator in case the resistance of the field winding is increased, then output voltage will decrease.

Last Answer : A D.C. generator can be considered as rotating amplifier.

Last Answer : A cumulatively compounded long shunt generator when operating as a motor would be differentially compounded long shunt.

Last Answer : In a D.C. generator, the critical resistance refers to the resistance of field.

Description : The e.m.f. induced in the armature of a shunt generator is 600 V. The armature resistance is 0.1 ohm. If the armature current is 200 A, the terminal voltage will be?

Last Answer : The e.m.f. induced in the armature of a shunt generator is 600 V. The armature resistance is 0.1 ohm. If the armature current is 200 A, the terminal voltage will be 580 V.

Last Answer : Flashing the field of D.C. generator means creating residual magnetism by a D.C. source.

Last Answer : If a D.C. generator fails to build up the probable cause could not be field resistance less than the critical resistance.