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POWER PLANT ENGINEERING

NME:801

Presented byMD GULFARAZ ALAMAssistant professorJETGI Barabanki

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UNIT-V

Electrical system

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Introduction Without having knowledge about electrical equipment. Power generation from

the power plant is difficult to understand. Hence it is necessary to have an idea about role of

electrical equipment. The main electrical equipments are as follows; Generator and generator cooling Transformers and their cooling Bus bars Excitors Reactors Circuit breakers Switch board Control room equipment

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Generators and motors: In a generator, an e.m.f. is produced by the movement of a coil in a magnetic field. The current produced by the e.m.f. Interacts with the field to produce a mechanical force opposing the movement, and against which the essential movement has to be maintained. The electrical power ei is produced therefore from the mechanical power supplied.

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Cooling of transformersThe cooling of transformers differs from that of rotary

machinery in that there is no inherent relative rotation to assist in the circulation of ventilating air. Luckily the losses are comparatively small, and the problem of cooling (which is essentially a problem of preserving the insulation-solid and liquid from deterioration) can in most cases be solved by reliance on natural self-ventilation. The various methods are.

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Bus-bar When a number of

generators or feeders operating at the same voltage have to be directly connected electrically, bus-bars are used as the common electrical component.

Single bus-bar system

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Busbar protection Busbars and lines are

important elements of electric power system and require the immediate attention of protection engineers for safeguards against the possible faults occurring on them.

Busbars in the generating stations and sub-stations form important link between the incoming and outgoing circuits. Fig: Fault type bus bar

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Pollution from thermal power plants.

Thermal power plants contribute to 13% of air pollution. The main pollutants are stack emissions; fly ash generation and fugitive

emission in coal handling. All three thermal power plants need better use of their emission control

devices and the fly ash that they generate. There is an immediate need to use beneficiated/washed coal, which has

a maximum ash content of 30%, which will reduce fly ash generation by about 25%. It has also been recommended to the Thermal Power Stations to examine the possibility of installing Bag

House Filters in order to control emission of particles between the size of PPM 2.5 to PPM-10.