Download as docx, pdf, txt or read online from scribd. Open circuit and short circuit tests on single phase transformer. For the braking operation in dynamic braking, the motor is connected in two ways. The working principle of a dc shunt motor is, whenever a dc motor is turned on, then dc flows throughout stator as well as the rotor. In other words, all of the electric power which is supplied to the motor is not. This is the best and simplest method to find the efficiency of a constantspeed dc machine e. The dc shunt motor construction is the same as any type of dc motor. A mock theory test is related to the driving of a car. In this method, a brake is applied to a watercooled pulley mounted on the motor shaft as shown in fig. Brake test in one of the most simple way of finding efficiency of any kind of dc machine. I am an applications engineer at microchip technology in the security, microcontroller and technology division.
To conduct the no load test on the dc shunt motor and determine its. Dynamic braking or rheostatic braking of dc motor in dynamic braking, a braking resistor rb is connected across the armature as soon as the dc motor is disconnected from the supply mains. As the constant loss is known the efficiency can be predetermined at any load. Brake test also called as direct loading test of testing the motor. The power required to test a large machine is small. In this article we are going to discuss about brake test on d. C shunt motor is conducted and its performance curves are drawn. We can run the machine as a motor or as a generator. Dc machines can be tested by three different methods namely direct method, indirect method and regenerative method. To verify kirchhoffs voltage and current law in a passive resistive network. Brake test of dc motor is carried out as shown in figure below. Brake test is basically a load test of induction motor. It is a full load test and it requires two identical machines which are coupled to each other. In case of dc shunt motors, armature is disconnected from the supply and a rheostat variable resistor is connected across it.
Swinburnes test and speed control of dc shunt motor. Circuit diagram load test on dc shunt motor figure. Direct method of testing when conducted on a motor is also known as brake test. Assuming the spring balance to be calibrated in kilogram.
To obtain the performance characteristics of a dc shunt motor by load test. This article discusses what is a dc shunt motor, construction, working principle, circuit diagram, characteristics, brake test, speed control, applications. Dc injection electric brake 1 phase by energizing one coil of the motor. Just like most energy conversion devices, the dc shunt motor is not 100% efficient. Several paragraphs that explain the motivation of the. C of a dc shunt generator and to determine its critical. Thus, this method is an economical and convenient method of testing of dc machines.
Speed control of electrical motors is an old but evergreen topic in industries. Load test on dc shunt motor offered by unicon instruments, a leading supplier of dc shunt motor in sadar bazar, ambala, haryana. Theory the efficiency of the dc machine can be accurately determined by the regenerative method, normally known as hopkinsons test. For a dc generator the output power is wasted in resistor. Components of the shunt motor are the armature, labeled a1 and a 2, and the field, labeled f1 and f2. The coils in the shunt field are composed of many turns of small wire, resulting in low shunt field current and moderate armature current. Brake test on dc shunt motor free download as word doc. It is difficult to dissipate the large amount of heat generated at the brake. 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. As such, the field windings and armature are connected in a parallel combination, and in electrical terminology a parallel combination is known as a shunt. The motor now works as a generator, producing the braking torque. What is dynamic braking or rheostatic braking of dc motor.
Dc injection electric brake 3 phase a dc voltage is applied to the motor stator windings, creating a stationary magnetic field which applies a static torque to the rotor. The company was incorporated in 1954 and is registered with indiamart. As resistance increased, the value of the field current will reduce. Before starting the experiment the motor field rheostat must. Its speed is nearly constant,falling off as the load increases due to resistance drop and armature reaction. Introduction to dc motors 1 ee 448 lab experiment no. Dc motors although ac motors are used in most of the cases, dc motors have many applications and used for multipurpose applications. Magnetization characteristics of dc shunt generator. The shunt is generally used to protect the speed controller from a load drawing too much current, or to limit the speed of the attached motor. Generally, this test can be done for the low rated dc machines. Now close switch s1 and slowly increase the voltage supplied to 3phase induction motor using autotransformer until it rotates at the rated speed of dc machine. Load characteristics of dc compound generator with differential and cumulative connection. A belt around the air cooled pulley has its end attached to the spring balance s1 and s2.
Note that applying brake on any motor amounts to loading it. Load characteristics of dc shunt and compound motor. Dc motor principle a machine that converts dc power into mechanical energy is known as dc motor. Two basic methods used for braking a motor dc injection. Brake test is also a method of finding efficiency of dc motors. The brake test is the one kind of load test on dc shunt motor. What is theory of brake test on dc shunt motor answers. In this test the efficiency of the machine at any load is predetermined. 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. This motor can be constructed with the basic parts like field windings stator, a commutator and an armature rotor. Working principle from the above circuit diagram, we can conclude that if we want to increase the speed of the shunt motor, we will vary the field resistance. To perform the brake test on the given dc compound motor and to obtain the. The load test can be conducted by using a belt brake or rope brake. 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. It is a direct method and consists of applying a brake to a. Hopkinsons test is another useful method of testing the efficiency of a dc machine. Several paragraphs that explain the motivation of the experiment. This is the complete theory of brake test on dc shunt motor including laboratory manual. This is part 1 in a 4 part series of webseminars related to controlling a brushed dc motor using a microcontroller.
For a constant applied voltage, the field current is constant for a d. Brake test on dc shunt motor electric motor electrical engineering. 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. Speed control of dc shunt motor with field and armature. To perform the brake test on the given dc shunt motor and to obtain the. Phase induction motor, dc shunt motors but almost no literature. Brushed dc motor basics hello, my name is john mouton. One of these two machines is operated as a generator to supply the mechanical power to the motor and the other is operated as a motor to drive the generator. Load test on singlephase transformer and three phase transformers. What is the break test on a 3phase induction motor.
In this method, we find the mechanical friction and windage and iron losses of the machine. What is a dc shunt motor and its advantage and disadvantage. Electrical machinel dc laboratory manual grietelectrical and. The shunt motor runs at a speed defined by the expressions. Scribd is the worlds largest social reading and publishing site. Retardation test or running down test on dc machines. Heat produced due to friction between belt and brake drum is reduced by pouring. Open circuit and load characteristics of separately and self excited dc shunt generators. The open circuit characteristics for a dc generator are determined. Swinburnes test is the most commonly used and simplest method of testing of shunt and compound wound dc machines which have constant flux. Electrical and electronics engineering lab manual pdf.
Hence dc shunt generator is called constant voltage generator. Schematic diagram for hopkinsons test on dc machine. Study 63 terms industrial motor control braking test. The field current lf is obtained from an external independent dc source. 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. Riosque y zack special edition hd recommended for you.
Dc motor electric brakes is of two kinds, depending upon the application of the drive. To draw the performance characteristics of the given dc shunt motor by. Speed control of dc shunt motor with field and armature rheostat control 79 2. Shunt dc motor the shunt motor is probably the most common dc motor used in industry today.
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