Describe how a squirrel cage motor is built, and classify it as either an induction motor or a synchronous motor. Working principle of a dc motor the dc motor is the device which converts the direct current into the mechanical work. Shadedpole motors have stators constructed similarly to what other motor. Because they convert electrical energy to mechanical energy, they are the interface between the electrical and mechanical systems of a facility. Ac synchronous generator alternator construction and. The figure above shows the family tree of the ac motors described in this chapter. The field windings of a series motors are connected in series with the armature windings. In addition to this, single phase motors are reliable, cheap in cost, simple in construction and easy to repair. Single phase induction motor split phase, capacitor and. Jan 29, 2019 the capacitor motor, which belongs to the singlephase induction motor, is explained in this video. Bldc motor works on the principle similar to that of a conventional dc motor, i. Read here to know about these electrical motors and their exhaustive classification.
It is also called asynchronous motor because it does not run at a synchronous speed. Construction of induction motor the three phase induction motor is a preferable type of motor. For this only the operating voltage, the motor rating, the various shortcircuit ratings and coordination types are. Be sure the motor shaft key is captive before the motor is energized. Diagnostic methods used for induction motors protection. An induction motor can be defined as the ac electric motor device in which a power source fed by the alternating current with the help of a primary winding. The rotor and stator windings are connected in parallel.
It is logical that the least expensive, lowest maintenance type motor should be used most often. How does a singlephase induction motor capacitor induction. An introduction to electric motors stmicroelectronics. When a coil rotated about on axis perpendicular to the direction of uniform magnetic field, an induced e. Brushless dc motor bldc construction, working principle. The threephase induction motor is the extensively used for various kinds of industrial drives. An electrical motor is an electromechanical device which converts electrical energy into mechanical energy.
Learn a brief history of the electrical power systems construction. Failure to properly ground the frame of the motor can cause serious injury to personnel. Magnetism and induction motor speed relationship motor performance motor nameplate information motor construction. The brushless dc motor, actually an ac motor, is replacing the conventional brushed dc motor in many applications.
Jan 06, 2019 ac series motors are also known as the modified dc series motor as their construction is very similar to that of the dc series motor. Ac induction motors how ac motors work explain that stuff. Basic principle behind the working of an ac synchronous generator is also faradays law of electrical induction, somewhat similar to working of a dc generator. Alternating current motors or ac motors are built on the principle that nikola tesla discovered in the late 19th century. An ac motor of this type may be part of a pump or fan or connected to some other form of mechanical equipment such as a winder, conveyor, or mixer. Generating ac ac can be produced using a device called an alternator. Also ac motor has to be precisely definedunder balanced and unbalanced loading conditions. Singlephase induction motor threephase induction motor singlephase induction motor there are probably more singlephase ac induction motors in use today than the total of all the other types put together.
The ac induction motor is well suited to applications requiring constant speed operation. The conditions for which motor protection is ac can be neededseparated into two main groups. In an induction motor, the electric current in the rotor needed to produce torque is obtained via electromagnetic induction from the rotating magnetic field of the stator winding. The first invertersconverters used motorgenerator sets, but were costly, heavy and inefficient. Figure 81 shows the motor output torque as a function of shaft speed with full rated voltage applied to the motor. Generally, it is known as the asynchronous motor because its running speed is less than its synchronous speed. Both direct current dc and alternating current ac motor types are. An ac motor is an electric motor driven by an alternating current ac. Thus, a dc generator or a dc motor can be broadly termed as a dc machine. Motor speed relationship the synchronous speed of an ac motor is the speed of the rotating magnetic field set up by the stator winding synchronous speed rpm 120 x frequency divided by the number of poles. A dc generator can be used as a dc motor without any constructional changes and vice versa is also possible.
The rotor is separated from the stator by a small airgap which ranges from 0. The life of ac servo motor depends on bearing life. Dc motors although ac motors are used in most of the cases, dc motors have many applications and used for multipurpose applications. Its operation is based on the principle that when a current carrying conductor is placed in a.
The first invertersconverters used motor generator sets, but were costly, heavy and inefficient. The stator of an induction motor consists of 3phase windings, which when connected to a 3phase supply creates a rotating magnetic field. The electric motor operation is based on the following points. Learn the principle of power factor improvement and evaluating the cost of electricity. The electrical design areas of a universal motor are the magnetic. Mostafa elshahed objectives learn a brief history of the electrical power systems construction. The stator and rotor do the work, and the enclosure protects the stator and rotor. The characteristics of a shunt motor reveal that it is an approximately constant speed motor.
The efficiency of ac servo motor is less and is about 5 to 20%. To show the performance of a motor when connected to a load, a typical speedtorquecharacteristic for a fan is plotted along with the motor speedtorque characteristic in figure 82. Generator is a device which is used to convert the mechanical energy in to electrical energy is called electric generator. Construction of dc motor all parts of dc motor in details. Basically, an ac motor is a type of motor that is operated by an alternating current. Single phase induction motor double revolving field theory the threephase induction motor starting torque inversely depends on the slip this implies that a small positive slip 0. The motor is controlled by applying a voltage to the motor leads. If a seried dc motor has a laminated stator frame, it can run effectively htt l d iki di iki di 667 from an ac supply as well as dc, this is the. As a consequence of reaction force, the magnet will experience an equal and opposite. Pdf rotor and stator temperature rise in induction motors is.
By convention, q is shown as positive above the horizontal, when the circuit is inductive, and vice versa when capacitive see. Thus, as an electrical and electronics engineer or hobbyist we must know a few basic concepts about these types of machines we use regularly in our life. This type of motor has three main parts, rotor, stator, and enclosure. Ac motors, motor control and motor protection bill brown, p. Introduction to ac motors ac motors electronics textbook. In general, the induction motor is cheaper and easier to maintain compared to other alternatives. Know about the different categories that these motors can be classified into. Pdf design and construction of induction motor thermal. The induction motor is made up of the stator, or stationary windings, and the rotor. The above diagram shows the configuration of stator winding.
Introduction to ac motor construction instrumentation and. Single phase motors are very widely used in home, offices, workshops etc. This article outlines basic construction and working of a dc generator. The ac motor commonly consists of two basic parts, an outside stator having coils supplied with alternating current to produce a rotating magnetic field, and an inside rotor attached to the output shaft producing a second rotating magnetic field. Use correct material handling equipment to avoid injury. The rotor and stator are each connected from a different power supply, this gives another degree of freedom for controlling the motor over the shunt. Compare the types of rotors used in ac generators, and the applications of each type to different prime.
Ac induction motors are also the most common motors used in main powered home appliances. Construction of dc motor nearly looks like the construction of dc generator, originally when the dc machine starts working we cant identify whether its a dc generator or motor, briefly dc motor consists of stator. The split facing technique of ac motors is given in. A universal motor is a singlephase series motor, which is able to run on either alternating current ac or direct current dc and the characteristics are similar for both ac and dc. Have you ever noticed what kind of motor drives the ceiling fan. Lecture 6 three phase induction motors cairo university. As a result, the voltage level also reverses along with the current. Applications of threephase induction motors of size varying from half a kilowatt to thousands of kilowatts are numerous.
An acm generates more power comparing with a dc motor that has the same dr. List the advantages and disadvantages of the two types of ac generators. The rotor is not connected electrically to the supply but has current induced in it by transformer action from the stator. Some include a squirrelcage structure to bring the rotor close to synchronous speed. Explain how this motor can be operated as either a synchronous motor or a plain induction motor. Less common, ac linear motors operate on similar principles as rotating motors but. It works on the principle of lorentz law, which states that the current carrying conductor placed in a magnetic and electric field experience a force. Describe the differences between the two basic types of ac generators. The principle of an ac motor is that electric current is applied to electromagnets, creating a rotating magnetic field to convert electrical energy to rotation mechanical energy. For small power conversion, the single phase ac motors are mostly used. Free download induction motor seminar ppt, pdf report. Introduction to ac motor construction instrumentation. In this session we will provide you some introduction to ac motor construction.
Table 1 gives information of most likely issues that call for ac motor protection. Dc motor principle a machine that converts dc power into mechanical energy is known as dc motor. In fact, when the machine is being assembled, the workmen usually do not know whether it is a d. Threephase ac induction motors are commonly used in industrial applications. Schematic representation of a sinusoidal voltage of magnitude e applied on a circuit with a resistive load r. The construction generally consists of a stator, which is made up of powerful permanent magnets. What does the grand total column on a work order for repairing an electric motor. We have the information to design and manufacture armature and stator replacements for your twmc motors, and motors from other manufacturers as well. Punmia class 12 ip text book pdf cclass 7 hindi ulike class 9 sst endglish business knowledge for it in private wealth management construction surveying and lay out power training for combat business studies textbooks fono engelish speak rosetta stone american english free download guide to navigation resection surveying haile giorgis mamo books science pdf. Ac motors principle of operation resources for engineers. The phase differences between the three phases of the. Before we move on to ac motors, lets quickly summarize whats going on here.
Three phase ac induction motors rated 1 hp 750 w and 25 w with small motors from cd player, toy and cddvd drive reader head traverse for higherpower applications where a polyphase electrical supply is available, the threephase or polyphase ac induction motor is used. List and describe the more commonly used equipment in an electric substation. Nov 27, 2019 an electrical motor is an electromechanical device which converts electrical energy into mechanical energy. They run at a constant speed from noload to the full load. It is based on the principle of electro magnetic induction. Main motor windings and all accessory devices associated with the work area are disconnected from electrical power sources. The entire construction bars and end rings resembles a squirrel cage and hence the name. During the power stroke the pressure falls from its maximum combustion value 4755 kgcm 2, which is usually higher than the greater value of the compression pressure 45 kgcm 2, to about 3. Modern inverters use solidstate designs and microprocessor controls to produce high quality ac power very. The phase relation between the rotor and stator magnetic field i. From the relationships shown above among s, p, q, e, i, and. Grounding should be in accordance with national and.
Be careful it can hurt to tangle with a threephase motor. The rotor of an induction motor can be a squirrel cage rotor or wound type rotor. Differentiate between the various types of generating electric power stations. All about motors 88 motor protection selection aids the eaton selector slide enables you to determine quickly and reliably which motor starter is the most suitable for the application concerned. Avoid long exposure in close proximity to machinery with high noise levels. The synchronous type ac servo motor uses permanent magnet while induction type doesnt require it. Lathes, drills, boring mills, shapers, spinning, and weaving machines series motor. Synchronous and asynchronous alternating current motors theacmsare simplier instructure andmore economicthandcms. Induction motors work on the principle of electromagnetic induction. The direction is changed by reversing the polarity on the leads. Ac induction motors are also the most common motors used in. And, the stepper motor, a digital version of the motor, is driven by alternating current square waves, again, generated by solidstate circuitry.
Those induction motors which employ squirrel cage rotor are called squirrel cage induction motors. The three phase ac motors are mostly applied in the industry for bulk power conversion from electrical to mechanical. Starting method for induction motors a 3phase induction motor is theoretically self starting. Receiving inspect the motor for damage before accepting it. Speed control of 3 phase induction motor by using vvvf ac drive. A successful salesman for general electrics motor division once remarked to one of your instructors that, when asked by a customer how a motor. Ive been seeing a lot of these videos with so called free energy and infinite energy motors and i was very curious.
Ac to ac converters are used for converting the ac wave forms with one particular frequency and magnitude to ac waveform with another frequency at another magnitude. So, this document provides information about single phase induction motor, construction stator, rotor, working principle, types of single phase induction motors, starting methods of single phase induction motors, and applications of single. However, the majority of motors are constructed with an even. An induction motor also known as an asynchronous motor is a commonly used ac electric motor. Know where these different types of motors are used. These types of motors are known as selfstarting induction motors. This conversion is mainly required in case of speed controlling of machines, for low frequency and variable voltage magnitude applications as well. A 3 phase induction motor has two main parts i stator and ii rotor.
The maximum torque is limited by the current rating of the motor and it is obtained at zero speed startup. It is mostly used in industrial drives because it is very reasonable and vigorous, economical and reliable. The life of dc servo motor depends on the life on brush life. In this work, digital temperature sensors are installed on rotor and stator windings. Basically, an ac generator is an electrical machine that converts mechanical energy into electrical energy in the form of alternating current ac. The most common type of ac motor being used throughout the work today is the induction motor. In a dc motor, the magnet and its magnetic field is fixed in place and forms the outside, static part of the motor the stator, while a coil of wire carrying the electric current forms the rotating part of the motor the rotor. The schematics shows the resultant current i in phase with the voltage v.
At least one of the two magnetic field is generated by a solenoid carrying a current. When the motor is coupled to equipment, ensure that system vibrations are within acceptable limit per iso 108161 to avoid failure of the motor. A motor converts electrical energy into mechanical energy ac alternating current reverses poles of electro magnetic coil 120 times per sec 60hz coils wound into the stator of the motor create rotating magnetic field magnetic field passing through. Advantages of 3 phase induction motor generally easy to build and cheaper than corresponding dc or synchronous motors induction motor is robust. Basic construction and operating principle like most motors, an ac induction motor has a fixed outer portion, called the stator and a rotor that spins. Alternating current ac alternating current describes the flow of charge that changes direction periodically. Ac is used to deliver power to houses, office buildings, etc. In the case of three phase ac alternating current operation, the most widely used motor is a 3 phase induction motor, as this type of motor does not require an additional starting device. The ac motor commonly consists of two basic parts, an outside stator having. The rotor magnetic field may be produced by permanent magnets, reluctance. Almost all the domestic appliances such as refrigerators, fans. This application note discusses the basics of an ac induction motor.