What is armature reaction? Explain briefly the cross magnetizing and de-magnetizing effect of a loaded generator

Armature reaction: The current flow in the armature conductors of a dynamo has an important and undesirable effect upon the dynamo’s operation. The current in the armature produces a flux and it is the interaction between this flux and the field flux that is called armature reaction.

Cross magnetizing and demagnetizing effect: The effects of the armature flux my be analyzed by considering the flux to consists of two components that are at right angle to each other as shown in fig. One component is at right angle to the field, and because this component crosses the main –field flux, it is known as the cross –magnetizing component of the armature flux. The second component is in the same plane as the main field flux . The direction of this component is opposite to the direction of the main field flux, with the result the it tends to reduce the effect of the main field flux. This component of the armature flux , is known as demagnetizing component of the armature flux.

Elimination: A method to reduce the armature flux on large machines is by the use of compensating windings .These windings are placed in the pole faces of the field pole can run parallel to the armature conductors. A connection is made from one of the brushes to one end of this winding, so that current from the armature must first pass through this winding before going to the load. The direction of current through the winding is opposite to that of the current in the armature conductors under the pole. The location of the compensating winding and of the connection of the winding is shown in fig. indicates that the current in the armature conductors located under the north pole carry current away from the observer , therefore the direction of current following in the part of the compensating windings situated in the north pole is toward the observer. The direction of flux due to the current in the armature conductor shown in fig. will be from the brush to the bottom brush. Since the current in the compensating winding is opposite in direction to the current in the armature conductors, the flux product by the current in the compensating winding will be opposite in direction to the armature flux. The compensating flux , being opposite in direction to the armature flux, tends to cancel the armature flux. If the armature current increases, the compensating current increases, so that the armature flux is cancel for all load conditions.

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Why a dc generator fails to build up voltage?

How can the problem be remedied : No residual magnetism, reversed field connection and high resistance of field circuit are responsible for the failure of build up process of a dc generator. The factors are explained below: No residual magnetism: For the starting build up process requires some residual magnetism in the magnetic circuit then no voltage will be generated that can produce current flow through field circuit. Reversed field connection: The voltage induced inside the coil of field circuit due to residual magnetism that can permit the flow of current. For the following direction of this flux will be created and the direction of this flux will be same direction as the residual flux. If the field connections are reversed the lines of flux produced by current flow will oppose the residual flux, as a result generate voltage will decrease rather than increase. So voltage build up process failed. Field circuit resistance too high: A field

How to Calculate Heat Rate of Generator Engine?

Types of Power Plant (Technology) Natural Gas Based power plant technology Diesel power plant technology Heat Rate of Engine= Fuel Flow or Fuel burned * Fuel Heating Value / Power Output 1 Liter Diesel = 0.85 Kg Example: Heat Rate of Diesel Generator at 100% Load Engine Model- 2506A-E15TAG2 Engine Capacity=400 eKW Fuel Consumption=84 L = 71.4 Kg Electrical Energy Output = 400 KW Heating Value of Diesel = 42.5 MJ/Kg Heat Rate of Engine= Fuel Flow or Fuel burned * Fuel Heating Value / Power Output Heat Rate of Engine = 71.4 Kg * 42.5 MJ/Kg /400KW Heat Rate of Engine =7.58 MJ/KWH Heat Rate of Gas Generator at 100% Load Engine Model- VHP5904LTD Engine Capacity= 900 eKW Fuel Consumption= 271 Nm 3 Electrical Energy Output= 900 KW Fuel Consumption= 0.28 Nm3/KWH Heating Value of Natural Gas= 35.22 MJ/ Nm 3 Heat Rate of Engine= Fuel Flow or Fuel burned * Fuel Heating Value / Power Output

Packing, Seals and Gaskets

Packing, seal and gasket resists the flow of fluid from machinery face, head, joint and machinery gap or clearance. Packing materials: Fiber, asbestos, cotton, synthetic materials, plastic, Teflon, graphite etc. Packing structure: Twisted, Braided and Consolidated. Gasket: A gasket is a mechanical seal that fills the space between two mating surfaces, generally to prevent leakage from or into the joined objects while under compression. Gaskets allow " less-than-perfect " mating surfaces on machine parts where they can fill irregularities. Gaskets are commonly produced by cutting from sheet materials, such as gasket paper, rubber, silicone, metal, cork, felt, neoprene, nitrile rubber, fiberglass, or a plastic polymer (such as polychlorotrifluoroethylene) Figure : Gaskets Name of the gasket uses

What are the main components of Automobile?

There have five basic parts for Automobile and they are given bellow: 1. Engine: Engine which is known to all as a power plant. Engine is the source of power which makes the car wheels rotate and the car move where it supply power to lubricating, fuel, electric and cooling systems. 2. Frame: Frame support the engine, body and wheels. 3. Power train: Power train transmit the power engine to the car wheels where its contain clutch, transmission, propeller shaft, axles and differential. 4. Car Body 5. Car body accessories: A car body accessory contains the heater, lights, radio, windshield wiper and convertible top raiser.

what is the difference between long shunt and short shunt dc generator?

How do they differ from normal generator? Draw their V-I characteristics and explain them? In short shunt connection the shunt field is connected directly across the armature terminals and the armature connection equals the sum of the shunt field current plus the load current . In this instance the load current flow s through the series field winding so that the load current and series field current are one and same. In long shunt connection the voltage across the shunt field is the same as the terminal voltage of the generator and current in the armature will be the current in the series field. The armature current equals the shunt field current plus the load current. A shunt generator has the field circuit connected directly across the armature. As more devices connected in parallel the load on the generator increases that the generator current increases which results decrease in terminal voltage of the generator.

Definition of Dwell Angle, Spark Angle, Firing order and Heat Path/spark plug reach

Dwell angle: It is the amount of time in degrees that contact point remain closed between each opening is called dwell angle. Spark angle: Spark plug is a device which device electric current from ignition system to combust on chamber of a S.I engine to ignite the compressed air fuel mixture in the form of spark at the end of compression stroke. Heat path/spark plug reach: Heat range is cylinder to heat combustion chamber. Firing order: Firing order is defined as the order on sequence in which firing takes place in every cylinder of a multi-cylinder engine.

Carriage and Main Parts of Carriage

Carriage: Between the head stock and tail stock that had several forms and serve to support move and control the cutting. Main Parts of Carriage : 1. Saddle 2. Cross-slide 3. Apron 4. Tool Post 5. Compound rest Common Operations of a Lathe Machine: 1. Turning: Turning is divided in two types and they are a. Straight Turning and b. Taper Turning. 2. Facing 3. Necking 4. Knurling 5. Parting 6. Thread cutting 7. Forming

Therbligs and Basic 17 motion name of therblig

Therbligs : A graphical representation of the co-ordinated activities of an operators body members. These activities ar described in terms of basic or fundamental motions known as therbligs. At the time Frank Gilbreth was doing his work in the field of motion study, he also concluded that any manual activity could be described in terms of 17 fundamental motions. This comparable to our being able to describe every word in the English language in terms of some of the 26 letters of the alphabet. Each of these fundamental motions is called a Therblig. Basic 17 motion name of Therblig : Name of Therblig Letter abbreviation Search Select Grasp Transport empty Transport loaded Hold Release Load Position Pre-position Inspect Assemble Disassemble Use Unavoidable Delay Avoidable Delay Plan Rest Sh ST G

what is PIV drive? Why is PIV drive more effective than any other system of drive?

PIV Drive: A stepless drive where the transmission of torque takes place infinitly variable without slip is called PIV drive. There are some advantages of PIV drive: there is no slip in the transmission of power. Maximum transmission of power. Speed can be changed at running condition Any range of slip can be obtain It give constant cutting speed for the above reason PIV drive is more effective than any other system of drive

Differentiate among progressive die, compound die and combination die.

Progressive die : The dies which performed two or more operations at different stages every time the ram descends is known as Progressive die. The principle advantage of Progressive die is in the number of operations that can be achieved with one handling of the stock strip. The main disadvantage is that work pieces may become “dished” as they pushed through the die as they generally have very little support. Compound die : A compound die differs from a progressive die in that it performs two or more cutting operations during one stroke of the press at one station only. Compound dies are slower in operation than progressive dies but they have advantages for certain jobs, especially where tolerance are close (1) the cutting operation, by the action of the knockout plate ,ensures flatness of the blank.2 Large parts can be blanked in a smaller press if compound dies rather than progressive dies are used. Combination dies: A die in which a cuttin

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