What is dynamic braking or rheostatic braking of dc motor. You become familiar with the measuring circuit for commissioning a direct current shunt motor. This paper discusses the speed and torque control of a shunt dc motor through matlab simulink simulations. Thus the speed of dc motor is given by, eb v i a r a. Dc shunt motor theory quiz questions electrician practice tests. What you need is a variable dc power supply for this you need to know the ratings of the motor. For a dc generator the output power is wasted in resistor. Kothari, tata mc graw hill publishers, 3 edition, 2004. In this article we are going to discuss about brake test on d. Download full pdf ebook here speed vs armature current characteristics of dc shunt motor the back emf of dc motor is. For a standard brushed dc motor, it is easiest to do on a separately excited motor, where the field winding has separate. Regulation from the series 20h, using armature feedback, will be 2% of base speed. By indirect method of testing of dc machines, the efficiency of shunt and compound dc machines can be determined. The dc shunt motor is 120vdc with rated speed of 1800.
Aug 22, 2018 types of braking in a dc motor august 22, 2018 february 24, 2012 by electrical4u hello electrical people, you already know about the different types of motors that are available today and in this article, i shall discuss about the various techniques used to stop a dc motor or to bring it to rest as we cut off the supply. This method enables the determination of losses without actually loading the machine. Direct method of testing when conducted on a motor is also known as brake test. Brake test is also a method of finding efficiency of dc motors. Swinburnes test and speed control of dc shunt motor. Electrical and electronics engineering lab manual pdf. Methods of testing direct, indirect brake test swinburnes test hopkinsons test fields test retardation test applications of dc motors. Speed control of dc shunt motor with field and armature rheostat control 79 2.
Depending on the motors design a tachometer system should be included. Pb 2 in a brake test on dc shunt motor, the load on one side of brake band was 35kg and the other side was 5kg. Open circuit and short circuit tests on single phase transformer. Construction, circuit diagram, and its applications. Oct 28, 2015 brake test is a typical example of direct test. Brake test online download brake test shunt motor theory brake test shunt motor theory now welcome the most inspiring book today from very professional writer in. Determine torque, output of motor and efficiency of motor. To draw the performance characteristics of the given dc shunt motor by conducting load test. In a shunt motor, the field and armature windings are connected in parallel. If stabilized shunt or compound wound motors are to be used, the series field must be isolated and not connected. The shunt field windings of a dc shunt motor are made of smaller gauge wire, but they have many more turns than a serieswound dc motor.
Types of dc motors dc motor are of 3 types they are 1. Heres hoping you understand the basics of electrical machinery. The dc brakes are operated by a solenoid similar in that is being driven by the momentum of the armature design to the ac solenoid brake fig. Load test the load testing machine needed determine the. 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. Electrical machines 1 viva questions and answers in this post we had collected some of the most frequently asked electrical machines 1 viva questions with detailed answers. 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 determine the efficiency of the given dc shunt motor by conducting load test. The brake test is the one kind of load test on dc shunt motor. Feb 26, 2014 pb 2 in a brake test on dc shunt motor, the load on one side of brake band was 35kg and the other side was 5kg. Jul 11, 2019 a dc shunt motor also known as a shunt wound dc motor is a type of selfexcited dc motor where the field windings are shunted to or are connected in parallel to the armature winding of the motor. The general output variable of this actuator can be angular speed or angular displacement motion, but, coupled. To verify kirchhoffs voltage and current law in a passive resistive network. Thus the efficiency of dc motor can be calculated as below.
Generally, this test can be done for the low rated dc machines. The biggest advantage of swinburnes test is that the shunt machine is to be run as motor under no load condition requiring little power to be drawn from the. Riosque y zack special edition hd recommended for you. One of the most used actuators in control systems is a direct current dc motor. Pdf modeling and simulation of the dc motor using matlab. Third is the serieswound dc motor and fourth is the compoundwound brushed dc motor which is a combination of both the shunt and series wound brushed dc motors. Brake test on dc shunt motor free download as word doc. As resistance increased, the value of the field current will reduce. Therefore, the supply voltage v and the induced voltage e b i. Electrical and electronics engineering lab manual pdf eee. The characteristics of a shunt motor reveal that it is an approximately constant speed motor.
Mar 14, 2016 laboratory explanation of break test on dc shunt motor. Speed control of dc shunt motor with field and armature. Brake test on dc shunt motor electric motor electrical engineering. The servo brake and drive system motor test bench may only be placed into service with an additional. You learn the significance of the data included on the rating plate of a dc motor. Load test on singlephase transformer and three phase transformers. Such type of drive is used in a placed where high friction load or strong natural brake requires. The torque speed characteristics separate by excited shunt of the machine under dynamic braking mode is as shown in fig. If spring balances are calibrated in kilograms, the motor output is given by, motor output. In this method, a brake is applied to a watercooled pulley mounted on the motor shaft as shown in fig.
Theory the back emf for a dc motor is given by, p nz back emf, e b 60 a the number of poles, p the armature conductors, z and the number of parallel paths, a are constant for a particular machine. The high number of turns allows a strong magnetic field to be generated, but the smaller gauge wires provide a high resistance and limit the current flowing through the shunt coil. Given w5kg w25kg n0 rpm i70amp v420v d 1m therefore r0. The connection diagram of dynamic braking of dc shunt motor is shown below. The first type, is the permanent magnet brush dc motor. Though this method is simple, bt involves complication in the measurement of mechanical power input in the case of generator and output in case of a motor. Lathes, drills, boring mills, shapers, spinning, and weaving machines series motor. Though there are separate branches for the flow of armature current and field current. Equivalent circuit parameters are armature resistance ra 110 ohms, field resistance rf 2. The two are connected via a pair of brushes to a commutator ring, whi. The positive torque corresponds to the motoring operation.
Before switchon the dc motorgenerator set on, verify that the dc. Dc shunt motor armature the parallel combination of two windings is connected across a common dc power supply. A dc shunt motor also known as a shunt wound dc motor is a type of selfexcited dc motor where the field windings are shunted to or are connected in parallel to the armature winding of the motor. To find the various parameters such as torque, input power, output power etc. To obtain the performance characteristics of a dc shunt motor by load test. Electrical machinel dc laboratory manual grietelectrical and. The connection diagram for dc shunt machine is shown in the figure below. The power is required to supply the losses only, so there is no. For dynamic braking, the series motor is disconnected from the supply. Testing of dc motor, dc motor testing direct and indirect method october 28. Thus the efficiency of the dc shunt motor with the load is tested. The motor was running at 0rpm, its input being 70 amp at 420 v dc. Load test on dc shunt motor unicon instruments exporter. Jun 25, 2015 electrical machines 1 viva questions and answers in this post we had collected some of the most frequently asked electrical machines 1 viva questions with detailed answers.
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 dc shunt motor by direct loading. Dc starter face plate type suitable for above motor. No load test on dc shunt generator 1 connect the circuit as shown in figure 1 with switches s1 and s2 open. For conducting brake test on dc series motor, it must be ensured that belt is sufficiently tight before the motor is switched on to the sully as dc series motor shall not be started at no load. Brake test also called as direct loading test of testing the motor. One end of the rope is fixed to the floor via a spring balance s and a known mass is suspended at the other. Electrical machines lab provides the essential facilities to the students to augment their concepts about the fundamentals of transformers and rotating machines.
Since they are connected in parallel, the armature and field windings are exposed to the same supply voltage. Dec 29, 2015 the shunt field windings of a dc shunt motor are made of smaller gauge wire, but they have many more turns than a serieswound dc motor. The connection diagram of shunt motor braking with self and separate excitation is shown in the figure below. This article discusses what is a dc shunt motor, construction, working principle, circuit diagram, characteristics, brake test, speed control, applications. For a permanent magnet dc motor just reverse the polarity of the supply voltage. The armature terminals or supply polarity of a separately excited dc motor or shunt dc motor when running are reversed.
Analog ammeter and voltmeter are provided on the front panel sheet. The machine is running as a motor at rated voltage and speed. Losses and efficiency in dc machines and transformers condition for maximum efficiency testing of dc machines brake test, swinburne s test, retardation test and hopkinson s test testing of transformers polarity test, load test, phasing out test sumpner s test separation of losses. Testing of dc motor, dc motor testing direct and indirect. Scribd is the worlds largest social reading and publishing site. The direct tests can be used only on small machines. The lab is equipped with dc seriesshunt motor, compound motor, universal motor, singlephase induction motor.
470 777 1307 1335 1252 432 270 981 381 206 1199 1333 608 1350 17 903 407 1074 167 1475 828 676 400 1157 860 772 98 1102 1139 1198 1019