Overview the acdc motor theory course was specifically developed for electricians and electronic technicians as well as for the multicraft training needs of process and manufacturing facilities. Because loading will be applied directly on shaft of the motor by means of a belt and pulley arrangement. Brushed dc motor fundamentals microchip technology. Brake test on dc shunt motor free download as word doc. Dec 21, 2017 81 videos play all dc machines complete course includes fundamentals, motors and generators electrical is easy mix play all mix electrical is easy youtube troubleshooting a motor starter. Make sure that no load is applied on the motors and the motor field rheostat should be in minimum position. Dc motors dc motor theory dc motor theory dc motors are widely used to drive various equipment. The dc motor contains a stator and a rotor, the latter being more commonly called an armature. An ac motor works by applying alternating current to stator windings, which produce a rotating magnetic field. Dc drive is basically a dc motor speed control system that supplies the voltage to the motor to operate at desired speed. To find out how to reverse the direction of rotation of a series dc motor. The stator contains one or more windings per pole, all of which are designed to carry direct current, th ereby setting up a magnetic field. One end of the band is fixed to earth via a spring balance s. A compound wound dc motor also known as a dc compound motor is a type of selfexcited motor, and is made up of both series the field coils s 1 s 2 and shunt field coils f 1 f 2 connected to the armature winding as shown in the figure below.
If you happen to have a string of blinking christmas lights to use as a prop in illustrating a rotating magnetic field, this would be a good thing to show your students. A compoundwound motor has both a series and a shunt field winding, i. Like any other motor, series motors convert electrical energy to mechanical energy. In a brushed dc motor, the coils on the rotor utilize the motors magnetic eld to create torque on the axle. Electrical machinel dc laboratory manual grietelectrical and. The simple brake test described above can be used for small motors only, because in the case of large motors, it is difficult to dissipate the large amount of heat generated at the brake. We connect the compound dc motor with the series and shunt windings with opposite polarities giving us a differential connection and lots of flames coming out of the brushes while running. Compound wound dc motor or dc compound motor electrical4u. This parallel configuration allows independent path of current for field winding and armature. Compound wound dc motors basic drive circuits drive circuits are used in applications where a controller of some kind is being used and speed control is required.
A belt around the air cooled pulley has its end attached to the spring balance s1 and s2. Direct method of testing of dc machine, also known as brake test if carried out for a dc motor will be discussed in this post. The eighth lesson in the acdc motor theory course, this lesson demonstrates armature reaction, compensation, and induced voltage. Nov 02, 2015 load test on dc compound generator long shunt 1. A good material for the poles of a pmdc motor should have the apposite of the above. Suitable for use with intermittent loads such as lifts, hoists etc. A compound wound motor has both a series and a shunt field winding, i. The electric braking of a dc motor is of three types, i rheostatic or dynamic braking, ii plugging or reverse current braking and iii regenerative beaking. Dec 30, 2018 the open circuit test is needed to determine the open circuit characteristic or magnetizing characteristic of a dc machine. In case of short shunt compound wound dc motor, the shunt field winding is connected in parallel across the armature winding only. Construction and principle of operation of the shunt dc motor. Brake test it is a direct method and consists of applying a brake to a watercooled pulley mounted on the motor shaft as shown in fig. Volume 2 of 4 module 3 dc circuits this module introduces the rules associated with the reactive components of inductance and capacitance and how they affect dc circuits. The development of the electric motor in modern times has indicated the truth in this theory.
Compound motor series and shunt windings in the same machine combine to make the field flux. Brake test is also a method of finding efficiency of dc motors. That is the reason behind naming it a dc shunt motor. This course consists of 11 interactive, online lessons that address ac and dc motor theory. One end of the rope is fixed to the floor via a spring balance s and a known mass is suspended at the other end. The field current lf is obtained from an external independent dc source. The open circuit test gives the mmf and hence the excitation current or field current needed to generate the required voltage on no load at a fixed speed. Brake test on dc compound motor free download as word doc. The armature and its windings are located in the path of this magnetic field, and. Apr 25, 2018 dc machines can be tested by three different methods namely direct method, indirect method and regenerative method. Brake test of dc motor is carried out as shown in figure below. Write the necessary magnetic polarities n for north and s for south on the armatures electromagnet pole tips, in order to. A dc motor may be thought of as a series of electromagnets, radially spaced around a common shaft. Induction motor theory jerry bednarczyk, pe course content introduction the ac induction motor is well suited to applications requiring constant speed operation.
Dc motors although ac motors are used in most of the cases, dc motors have many applications and used for multipurpose applications. In a compound motor, we have both series winding and parallel winding. A dc generator requires an excitation circuit to generate an induce voltage depending on whether excitation. Differential compound dc motor connections youtube. The induction motor is made up of the stator, or stationary windings, and the rotor. Brake test also called as direct loading test of testing the motor. Jun 02, 2015 brake test it is a direct method and consists of applying a brake to a watercooled pulley mounted on the motor shaft as shown in fig. Dc machines can be tested by three different methods namely direct method, indirect method and regenerative method. Describe how a squirrel cage motor is built, and classify it as either an induction motor or a synchronous motor. Write the necessary magnetic polarities n for north and s for south on the armatures. Start the motor by using 3point starter and adjust the speed of the motor in the rated value by using rheostat of motor 4. Scribd is the worlds largest social reading and publishing site. Two basic methods used for braking a motor dc injection and dynamic photo credit. Using belt tightening hand wheels h1 and h2, the load of motor is adjusted to its rated value.
In this article we are going to discuss about brake test on d. Explain how this motor can be operated as either a synchronous motor or a plain induction motor. This is the ninth lesson in the acdc motor theory course. The concept of the rotating magnetic field is central to ac motor theory, so it is imperative that students grasp this concept before moving on to more advanced concepts.
A dc series motor will have its field windings connected in series with the armature. Objective identify the components of an ac motor and explain their function. Dc injection braking is a method of braking in which direct current dc is applied to the stationary windings of an ac motor after the ac voltage is removed. Brake test on dc shunt motor electric motor electrical. Both the field coils provide for the required amount of magnetic flux, that links with the armature. The cumulative compound wound dc motor is well adapted for this type of work. Fields test for series motor this test is applicable to two similar series. These terms relate to the type of connection of the field windings with respect to the armature circuit. A winding is connected in series with the armature as in a series dc motor. This lesson instructs the participant in the design of series. Dec 19, 2016 we connect the compound dc motor with the series and shunt windings with opposite polarities giving us a differential connection and lots of flames coming out of the brushes while running.
Electrodynamometer is an electrical break, in which the breaking force can be varied electrically. The extra terminal draws about 4 amps when connected high. And series field coil is exposed to the entire supply current, before being split up into armature and shunt field current as shown in the diagram below. The brake band is fixed with the help of wooden blocks gripping the pulley. Each type has unique operating characteristics and applications. In general, the induction motor is cheaper and easier to maintain compared to other alternatives. In this method, a brake is applied to a watercooled pulley mounted on the motor shaft as shown in fig. The speed and torque produced in a dc motor depends on a variety of factors.
Dc motor dc motor theory the dc motor has two basic parts. Experiment 7 series dc motor i objectives to determine the torquespeed characteristic curve. In case of dc shunt motors, armature is disconnected from the supply and a rheostat variable resistor is connected across it. To obtain the performance characteristics of a dc shunt motor by load test. The armature is made of coils of wire wrapped around the core, and the core has an extended shaft that rotates on bearings. When the losses of dc machine wellknown, then we can find the efficiency of a dc machine in advance at any desired load. Mar 23, 2019 a compound wound dc motor also known as a dc compound motor is a type of selfexcited motor, and is made up of both series the field coils s 1 s 2 and shunt field coils f 1 f 2 connected to the armature winding as shown in the figure below. In long shunt dc compound motor, the shunt field winding is connected across both armature and series field winding. As im only running motor unloaded on 12 voltage, any regulating effect may not be noticed. Compoundwound dc motors basic drive circuits drive circuits are used in applications where a controller of some kind is being used and speed control is required. Dc series motor theory quiz questions electrician practice.
My motor is a series motor with only one terminal available. Another simple method of measuring motor output is by the use of poney brake one form of which is shown in fig. The open circuit characteristics for a dc generator are determined as follows. Because the magnetic field rotates in this way, an ac motor does not need. Download as docx, pdf, txt or read online from scribd. In electrical terms, parallel is generally denoted as shunt. Characteristics of compound motor 34 compound motor characteristics are intermediate between the shunt and series motors torquespeed of compound motor shows that the motor has high starting torque together with a safe noload speed. Dc series motor theory quiz questions free online electrical practice tests. The dc compound motor consists of both series and shunt field windings. Brake test on dc compound motor electric motor electrical. This particular motor is of the permanent magnet type, with wire windings only on the armature. The dc shuntwound motor, running on direct current, has its field windings placed in parallel to the armature.
Earlier, the variable dc voltage for the speed control of an industrial dc motor was generated by a dc generator. Its operation is based on the principle that when a current carrying conductor is placed in a. Introduction a series dc motor is a motor whose filed windings consists of a relatively few turns connected in series with the armature circuit. Brushed dc motor theory and operation chris joyce, shane skikne, evan simpson, james nee january 8, 2014 abstract this study looked into the e ect of changing the material within the rotor of an electric motor. Dc compound motor or compound wound dc motor is also a selfexcited motor, but it is a compound of both series and shunt field coils connected to the armature winding, a series field winding connected in series with the armature and a shunt field winding connected in parallel to the armature. Same voltage is applied to both shunt winding and armature in this motor. Module 2 basic dc theory this module describes the basic concepts of direct current dc electrical circuits and discusses the associated terminology. Its operation is based on simple electromagnetic principle by which when the magnetic field created around a current carrying conductor interacts with an external magnetic field, a rotational motion is generated. Because the magnetic field rotates in this way, an ac motor does not need power or mechanical aid to be applied to the rotor. Dc motor principle a machine that converts dc power into mechanical energy is known as dc motor. N s this particular motor is of the permanent magnet type, with wire windings only on the armature.
Electrical machines laboratory roever college of engineering and. There are 3 main types of dc motor that are available. Armature reaction, compensation, and induced voltage. Introduction a series dc motor is a motor whose filed windings consists of a relatively few turns connected in. Dc compound motor definition, types, applications, equations.
Dc motor theory mem 639 realtime microcomputer control 1. In a brushed dc motor, the coils on the rotor utilize the motors magnetic eld. Basic motor theory introduction it has been said that if the ancient romans, with their advanced civilization and knowledge of the sciences, had been able to develop a steam motor, the course of history would have been much different. Swinburnes test for dc machines in this technique, the dc generator or dc motor is run as a motor at no load. Motor runs about the same with it connected high or low.
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