November 4, 2016 11 of 21 the test setup the dc machine to be tested and the dynamometer have already been placed on the bench and mechanically coupled. Dc generator is typically found in offgrid applications. Generators are invariably fitted with automatic voltage regulators which maintain the thermal voltage at its normal value by adjustment of excitation. These are the generators whose field magnets are energized by some external dc source such as battery. A simple explanation of the different types of dc generators. These kind of generators has provided field exciter terminals which are external dc voltage source is supplies to produce separately magnetic field winding. In selfexcited dc generators, the eld winding is connected across the armature. November 4, 2016 11 of 21 the test setup the dc machine to be tested and the dynamometer have already been placed on the bench. Magnetic circuits quantities and definitions, solving magnetic circuits with. A circuit diagram of separately excited dc generator is shown in the figure.
Types of dc generators diagrams included electrical4u. These characteristics of dc generators are very important in the design and operation of dc generators. When the rotor of this machine is rotated, the residual ux in the eld winding induces some voltage e r in the armature winding as shown in fig. Torque in a dc motor is produced by the product of the magnetic field created by the field winding or magnets and the current flowing in the armature winding. Dc generators electric generator components free 30. This article describes the new voltage control of dc generators based on load characteristic. Introduction to basic notions on electric power 5 electric current conductor lines of force fig. Home mcq dc generators multiple choice questions with answers on dc generators set 08 multiple choice questions with answers on dc generators. Describe the cause of sparking between brushes and commutator. This source of mechanical energy is called a prime mover. Dc motor, generators and energy conversion devices lecture notes. Dc generators electric generator components free 30day.
Various types of losses that occur in dc machines and how to calculate efficiency vi. Dc generator characteristics are the relations between excitation, terminal voltage and load exhibited graphically by means of curves. If a closed path is provided to the moving conductor then generated emf causes a current to flow. The dc generators training system includes a resistive load unit with six parallel branches of resistance and a total resistance of 33 ohms 3500 ohms, an inductive load unit with six parallel branches of resistance, and a lead set. Permanent magnet dc generators field coils excited by permanent magnets. On the other hand, a dc voltage source or an ac dc converter is required for synchronous generators in wind applications in order to produce the required excitation voltage for the field windings.
Mcq dc generators multiple choice questions with answers on dc. These generators give a seamless power supply directly into electric storage devices and dc power grids without novel equipment. The above figure shows a typical noload saturation curve or open circuit characteristics for all types of dc generators. A dc generator produces direct power, while an ac generator produces alternating power.
The above content is the basic working principle of dc generator, explained by single loop generator model. Ac generators are widely used for power generation, and they transform mechanical energy supplied by some source into electrical energy. An electrical generator is a machine which converts mechanical. Since then numerous organizations have performed extensive testing on our generators, including the us army. Methods for speed control of dc motors and applications of dc motors v. Principal of electrical machinery and optimization of. Dc generators mcq questions answers electrical engineering.
Internal or total characteristic ei a an internal characteristic curve shows the relation between the onload generated emf eg and the armature current i a. The polar dc generators are designed and optimized. Characteristics of generators and parallel operation of generators iv. Magnetic circuits quantities and definitions, solving magnetic circuits with electrical analogies, mechanics for motors and generators, electromagnetic induction and magnetic forces, construction of elementary dc generators, induced voltage in practical dc machines, power balance and. With larger amounts of power, a great deal more current flow occurs through the slip rings and brushes. Generators questions and answers free download posted on august 19, 2018 january 12, 2020 by engineer 7 comments posted in dc generator objective questions. Polars dc generators do not need to be oversized, having a generator that can limit the output power by. A dc generator is an electrical machine which converts mechanical energy into direct current electricityabove figure shows the constructional. The principle of operation of a dc generator is similar to that of the ac generator, which was discussed previously.
The action of a mechanical commutator switches the armature current from one winding to another to maintain the relative position of the current to the field, thereby producing torque. Other members of the family are the directcurrent dc motor or generator, the induction motor or generator, and a number of derivatives of all these three. Click here to download the pdf of this topic characteristics of dc generator. Categories dc generator, interview questions, objective questions. On the righthand end of the dynamometer is a clamp which locks the rotor and stator. A rotating armature coil passes through a magnetic field that develops between the north and. There are several types of direct current machines. To see other topics in basic electrical and electronics engineering click here. Polars small dc generators are also built to service prime power applications.
May 28, 2012 ac generators are widely used for power generation, and they transform mechanical energy supplied by some source into electrical energy. If a closed path is provided to the moving conductor then generated emf causes a current to flow in the circuit. Since then numerous organizations have performed extensive testing on our generators, including. This article outlines basic construction and working of a dc generator. There are two types of generators dc generators and ac generators. Dc generators have vast area of applications and the choice of a dc generator for a particular service depends upon its performance characteristics. Both dc and ac generators convert mechanical power to electrical power. The different types of dc motors and generators and their particularities. Dc motors and generators design, application and operation. This app is the standard program for the professional usage. The handbook includes information on alternating current ac and direct current. The dc generators training system requires electric machines and electricity 208 vac60 hz3 phase. May 31, 2019 dc generators are classified based on how their fields are excited i.
Sai is in development testing on a dc brushless starter generator as an enginedriven source of dc power rated at 2830 volts with a continuous load of 150400 amps over a speed range of 6,900 12,000 rpm. These kind of generators has provided field exciter terminals which are external dc voltage source is supplies to produce separately magnetic field winding shunt field for magnetize of the generator as illustrated in figure 2 as below. The applications of various dc generators are given as follows. Laminations of core are generally made of a case iron b carbon c silicon steel d stainless steel ans. This industrial motor training system includes resistive load and inductive load units. I a armature current i l load current v terminal voltage e g generated emf voltage drop in the armature i a. Dc generators free download as powerpoint presentation. The synchronous generator connection with wind turbine is shown in fig. Dc generators are classified based on how their fields are excited i. The synchronous electrical generator also called alternator belongs to the family of electric rotating machines. The phenomena of armature reaction and commutation iii. The adobe acrobat pro dc 2020 crack new version is one of the best programs which you can use to edit and modify your pdf documents and provides an excellent way to navigate large documents. The dc generators find much utilization in the devices that are used in application systems. Polars dc generators do not need to be oversized, having a generator that can limit the output power by regulating both current and voltage allows a 10 kw generator to be used for a 10 kw load without circuit breakers tripping, alternators or engines overheating.
Polars dc generator sets gensets meets both military and bellcore power applications. Hence, the terminal voltage is also the eld voltage and the armature current is the sum of load and eld. State how field strength can be varied in a dc generator. The operating principles of direct current dc motors and generators. Prime movers are divided into two classes for generators highspeed and lowspeed.
Difference between ac and dc generator compare the. Explain the effect of motor reaction in a dc generator. Types of dc generators study materials exams daily. Generator working principle and explain about ac and dc. A dc generator is an electrical machine which converts mechanical energy into direct current electricity. Sai is in development testing on a dc brushless starter generator as an. Learn about series, shunt, compound, selfexcited, and permanent magnet. The positions of the brushes of dc generator are so that the change over of the segments a and b from one brush to other takes place when the plane of rotating coil is at a right angle to the plane of the lines of force. Dc motor, generators and energy conversion devices lecture. Laminations of core are generally made of a case iron b carbon c silicon steel d stainless steel. Before we can explain the working principle of a dc generator, we need to cover the basics of generators there are two types of generators dc generators and ac. Basic ac electrical generators 5 rotating armature ac generators are typically used in applications involving small amounts of power. Multiple choice questions with answers on dc generators.
There are three methods of excitation, and thus three main types of dc generators. Introduction the outstanding advantages of dc machines arise from the wide variety of operating characteristics which can be obtained by selection of the method of. It is difficult and expensive to build slip rings and brushes to carry large amounts of current. In this chapter, the authors highlight the types and. C generators are classified according to the way in which a magnetic field is developed in the stator of the machine. Thus in dc generators, when armature is rotated with the help of a prime mover and field. Use realworld components to connect and operate dc generators.
Module 5 dc generators this module describes the types of dc generators and their application in terms of voltage production and load characteristics. Synchronous generator an overview sciencedirect topics. This energy conversion is based on the principle of production of dynamically. For more details about characteristics of dc generator click here. The magnitude of generated emf can be given by emf equation of dc generator. Internal or total characteristic ei a an internal characteristic curve. Hence, the terminal voltage is also the eld voltage and the armature current is the sum of load and eld currents. Apc starter generator line was designed for the starting of turbine engines and apus.
Multiple choice questions with answers on dc generators set. State the term that applies to voltage variation from noload to fullload conditions and how it is expressed as a percentage. This energy conversion is based on the principle of production of dynamically induced emf. Dc generators electric generator electronic engineering. Separately excited dc generators field coils excited by some external source. In this chapter, the authors highlight the types and characteristics of dc generator.
Adobe acrobat pro dc 2020 crack the adobe acrobat pro dc 2020 crack new version is one of the best programs which you can use to edit and modify your pdf documents. All generators, large and small, ac and dc, require a source of mechanical power to turn their rotors. What is common to all the members of this family is that the basic physical process involved in their operation is the conversion. The stored power is carries to loads through dc ac converters. There are three methods of excitation, and thus three main types of dc generators permanent.
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