Dc generator or direct current generator generates a voltage when speed and flux are met. State the term that applies to voltage variation from noload to fullload conditions and how it is expressed as a percentage. A dc generator can be used as a dc motor without any constructional changes and vice versa is also possible. Mesb443 electromechanical systems dc motors and generators magnetic force on a current carrying conductor the magnetic. Dc generator theory worksheet dc electric circuits.
While an acpowered generator is acceptable for running small appliances, a dc powered generator is ideal for running bigger motors and bigger appliances that require direct current to provide power. Motors, as well as generators, have similar features. A dc generator can be used as a dc motor without any constructional changes and vice versa is also. The basic principle of a dc motor is the creation of a rotating. Other members of the family are the directcurrent dc motor or generator, the induction motor or generator, and a number. Principle of dc generator and operation of dc generator principle of dc generator. Disadvantages of dc motors power supply, initial cost, and maintenance requirements are the negatives associated with dc motors rectification must be provided for any dc motors supplied from the grid. The outer frame of a generator or motor is called as yoke. Multiple choice questions with answers on dc generators. The principle of operation of a dc generator is similar to that of the ac generator, which was discussed previously.
The dc machines are classified into two types such as dc generator as well as dc motor. Principal of electrical machinery and optimization of electrical power. Dc generators power very large electric motors like those needed for subway systems. Dc motor and dc generator are similar from the mechanical perspective, however from a technical stand point, both differ from each other significantly. Thus, a dc generator or a dc motor can be broadly termed as a dc machine. A force is induced in a conductor that has a current going through it and placed in a.
A dc generator or direct current generator is one kind of electrical machine, and the main function of this machine is to convert mechanical energy into dc direct current electricity. This is a problem in dc power systems, as the generator will act as a load, drawing energy from the battery, when the engine or other prime mover device stops moving. Working principle of dc generator introduction to dc. Large dc motors are used in machine tools, printing presses, fans, pumps. Principal of electrical machinery and optimization of. Follow me constantly to find what pleased you and develop your knowledge, and now we should gather advantages and disadvantages of dc generators.
Number of poles is not is equal to number of parallel path. A rotating armature coil passes through a magnetic field that develops between the north and. A dc motor can be converted into a dc generator while the vice versa is also possible. This article discusses an overview of dc generators. Both dc and ac generators convert mechanical power to electrical power. Rather than oscillating back and forth, dc provides a constant voltage or current. Difference between dc motor and dc generator versus wiki. Pdf electromechanical systems dc motors and generators. Generators principle ofoperationdc generator converts mechanical energy intoelectrical energy. Difference between ac and dc generator in tabular form. Hence the basic essentials for an electrical generator are. The most significant difference between dc motor and dc generator lies in the conversion mechanism.
Whats the difference between ac, dc, and ec motors. An emf voltage is induced in a conductor if it moves through a magnetic field. Separately excited dc generators field coils excited by some external source. It consists of the same basic elements as a simple ac generator like the multiturn coil rotating uniformly in a magnetic field. Module 5 dc generators this module describes the types of dc generators and their application in terms of voltage production and load characteristics. Generating dc dc can be generated in a number of ways.
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 generators. On the righthand end of the dynamometer is a clamp which locks the rotor and stator. 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. But there is a good similarity with a dc motor also as far as construction is concerned. Dc motor questions and answers pdf dc generators questions and answers on dc. In the above difference between dc and ac generator, several higherlevel concepts are also included to give indepth insights about the dc and ac generators. Constructional details of a dc generator here we are dealing with a dc generator. The same benefits of ac over dc for generator design also apply to electric motors. The construction of a dc motor is considerably more.
Motors use the effect of forces on currentcarrying conductors in magnetic fields. Chapter 1 principles of operation of synchronous machines the synchronous electrical generator also called alternator belongs to the family of electric rotating machines. Dc machine construction, working, types, emf equation. The basics of dc and ac motors dc motors rely on carbon brushes and a commutation ring to switch the direction of the current and magnetic field polarity in a rotating armature. Home technical articles dc motor and generator design, application and operation dc motor history will recognize the vital role played by dc motors in the development of industrial power transmission systems, the dc machine being the first practical device to convert electrical power into mechanical power. Module 6 dc motors this module describes the types of dc motors and includes discussions of speed control, applications, and load characteristics.
Direct current dc direct current is a bit easier to understand than alternating current. What is the difference between a dc motor and a generator. Dc motor converts electrical energy into mechanical energy whereas dc generator converts mechanical energy into an electrical energy. Main types of dc motors are shunt wound and compound wound while the main types of dc generators are series, shunt and compound wound. To understand how the series and shunt field fluxes interact to produce the various compound generator terminal voltage vs. Types of dc generators diagrams included electrical4u. Explain the effect of motor reaction in a dc generator. Introduction to dc generator generator is machine that converts mechanical energy to electrical energy. Permanent magnet dc generators field coils excited by permanent magnets. Basic constructional parts of a dc generator are described below.
A dc generator produces direct power, while an ac generator produces alternating power. This article outlines basic construction and working of a dc generator. Testing of dc machines dc motor and dc generator iec 61850 substation automation fundamentals. Difference between dc motor and dc generator electrical. Yoke provides mechanical strength for whole assembly of the generator or motor. The direct current dc motor is one of the first machines devised to. Dc motor uses the lefthand rule of fleming while dc generator uses the righthand rule of fleming. Dc motors enable accurate torque regulation, when operating as a motor or as a generator, and rotation speed, independent of the line supply frequency. And the most important in dc generator working principle of dc generator which needs a lot of space and high interest. Characteristics of dc shunt generator to determine the internal and external load characteristics of a dc shunt generator the machine is allowed to build up its voltage before applying any external load. These were the main ac and dc generator differences. Basic construction details about design of dc motor or generator. In fact, ac and dc motor designs are very similar to their generator counterparts.
Dc generators will act as dc motors if connected to a dc power source and not spun at a sufficient speed. The following are the main parts of a dc generator. There are three methods of excitation, and thus three main types of dc generators. There are some disadvantages and advantages to using a dc generator. Multiple choice questions with answers on dc generators set 08 mcq dc generators edit practice test. The working principle of a dc machine is when electric current flows through a coil within a magnetic field, and then the magnetic force generates a torque which rotates the dc motor. Dc motors and generators design, application and operation. The principle of dc generator is to converts mechanical energy into electrical energy when a conductor move in a magnetic field in such a way conductors cuts across a magnetic flux of lines and emf produces in a generator and it is defined by faradays law of electromagnetic induction emf. While dc motors need brushes to make electrical contact with moving coils of wire, ac motors do not. This emf causes a current to flow in the conductor if its circuit is closed. This unit will discuss how these magnetic fields are produced in dc motors, and how magnetic fields induce voltage in dc generators. Home technical articles basics of dc motors for electrical engineers beginners. A dc machine is an electromechanical energy alteration device.