When a current carrying conductor is placed in a magnetic field, it experiences a force. The characteristics of a shunt motor reveal that it is an approximately constant speed motor. Load test on a dc shunt motor and determination of performance characteristics. Notice the shunt coil is identified as a coil of fine wire with many turns that is connected in parallel shunt with the armature. Thus the speed of dc motor is given by, eb v i a r a. Swinburnes test is the simplest indirect method of testing dc machines. Kothari, tata mc graw hill publishers, 3 edition, 2004. To obtain the performance characteristics of a dc shunt motor by load test. In the case of a dc motor, the magnetic field is produced by the field winding. 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 open circuit test is needed to determine the open circuit characteristic or magnetizing characteristic of a dc machine. Parts and principle of operation of a shunt dc motor.
Title of the experiment page no 7 retardation test on dc shunt motor. Set the inserted field resistance and the inserted armature resistance to their maximum values. Two types of speed controllers for electric cars are discussed. To determine the efficiency of the given dc shunt motor by conducting load test. By means of this method, the motor can be worked at any speed up to its maximum speed. A compoundwound motor has both a series and a shunt field winding, i. Tech eee atri eee department 4 code of conduct for the laboratories all students must observe the dress code while in the laboratory. Use figure 2 if your motor has a dual voltage shunt field. Brake test also called as direct loading test of testing the motor. Lathes, drills, boring mills, shapers, spinning, and weaving machines series motor.
And the armature winding is connected to external supply voltage hence it. This type of winding is called shunt winding and the motor shunt dc motor. All of the above 4 the usual test to find the efficiency of the traction motor is a. Dc starter face plate type suitable for above motor. Working principle of dc shunt motor your electrical guide. Speed control methods of dc shunt motor my tech info. On the other hand, back emf reduces marginally more than that the. Retardation test video lecture from dc motor chapter of electrical machine 1 subject for all engineering students. As you know that the construction of any type of dc motor is very similar to a dc generator. 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. To draw the performance characteristics of the given dc shunt motor by conducting load test. If both the currents are reversed the motor will run in original direction. C is applied to a shunt motor, the large inductive reactance of shunt winding will reduce the field current too much. In this test the efficiency of the machine at any load is predetermined.
Since in both cases same motor is used so losses are equal. In a shunt motor, the field winding, as we ll as the armature winding, is connected in parallel shunt directly to the dc supply lines. By indirect method of testing of dc machines, the efficiency of shunt and compound dc machines can be determined. Shunt motor is a special type of dc motor which runs at a constant speed. In a shunt dc motor, the armature and field windings are linked in parallel. To determine the efficiency of two similar shunt machines by regenerative method. Types of dc motors dc motor are of 3 types they are 1. Hence the armature current differs and the speed of a dc shunt motor will continue constant which is shown in the fig dotted line ab. A dc shunt motor also known as a shunt wound dc motor is a type of self excited dc motor where the field windings are shunted to or are.
Load test on dc shunt motor, dc shunt wound motor, direct. One of the main advantages of swinburnes test is that it a is applicable both to shunt and compound motors b needs one running test c is very economical and convenient d ignores any charge in iron loss 2. If the shunt field winding is only parallel to the armature winding and not the series field winding then its known as short shunt dc motor or more specifically short shunt type compound wound dc motor. Where dc motor of hp 12 of more requires frequent starting, stopping, reversing and speed control a drum type controller is used b three point starter is used c four point starter is used d all of the above 116. This method is an indirect method of testing a dc machine. Now in this article we are going to discuss about retardation test on dc machines. E b vi a r a here, eb back emf, in volts ia armature current, in amps ra armature resistance, in ohms v terminal voltage, in volts. If a dc shunt motor is working at full load and if shunt field circuit suddenly opens 117. Brake test is also a method of finding efficiency of dc motors. A dc motor must have 100% field strength to produce its maximum torque and to keep the armature amperage within proper limits. Notice that the motor is wired for shunt field operation and is connected to the variable dc source terminals 7 and n while the electrodynamometer is connected to the fixed low voltage ac source by the grey cable 1 in fig. Speed control of dc shunt motor and 3ph induction motor.
This is the best and simplest method to find the efficiency of a constantspeed dc machine e. Methods of testing direct, indirect brake test swinburnes test hopkinsons test fields test retardation test applications of dc motors. Analog ammeter and voltmeter are provided on the front panel sheet. Retardation or running down test this method is applicable to shunt motors and generators and is used for finding stray losses. It describes principle,procedure to find stray loss in dc shunt motor with mathematical analysis. If the dc line voltage is constant, then the armature voltage and the field strength will be constant. This is very efficient way to find out stray losses in dc shunt motors. Dc shunt motor theory quiz questions electrician practice tests. In electrical terminology, a parallel connection is called shunt. The various applications of dc shunt motor are in lathe machines, centrifugal pumps, fans, blowers, conveyors, lifts, weaving machine, spinning machines, etc. The purpose of retardation test on dc shunt machines is to. The power is required to supply the losses only, so there is no. C motor by either reversing the field current or armature current. Electrical machinel dc laboratory manual grietelectrical and.
Retardation test is also called as running down test. Brake adjusting the tension of belt, the load is adjusted to give the various values of currents. 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. Motor connections your motor will be internally connected according to one of the diagrams shown below. The resistances of the armature and shunt field are 0. Types of dc motors and their applications electrical4u. Retardation test on dc shunt motor for determination of moment of inertia of machines. Retardation test electric generator electric current. A good material for the poles of a pmdc motor should have the apposite of the above. To conduct load test on dc motor with shunt excitation and plot the typical characteristics.
The machine is running as a motor at rated voltage and speed. The main disadvantage of hopkinsons test for finding efficiency of shunt d. Online multiple choice questions electric machine design. No load test on dc shunt generator 1 connect the circuit as shown in figure 1 with switches s1 and s2 open. It is, therefore, apparent that the shunt motor should run at a reasonably constant speed. To conduct load test on dc shunt motor and to find efficiency. Use figure 1 if your motor has a single voltage shunt field. In electrical terminology, a parallel connection is termed shunt. Let us now solve some problems on shunt, separately excited and series motors.
Because loading will be applied directly on shaft of the motor by means of a belt and pulley arrangement. What is a dc shunt motor and its advantage and disadvantage. To know how to estimate and predict efficiency of a d. It is supplied with one ms powder coated electrical panel fitted with high insulation bakelite sheet. Whenever the shunt motor load is increased e b vi a r a and flux reduces as a result drop in the armature resistance and armature reaction. To discover the characteristic change in torque output of a dc shunt motor as it is loaded. In the previous articles we have seen brake test, hopkinsons test which are essential to find out dc machine efficiency. These connections are in accordance with nema mg1 and american standards publication 06. Since they are connected in parallel, the armature and field windings are exposed to the same supply voltage. Reduced field strength will cause high armature currents. Scribd is the worlds largest social reading and publishing site.
As resistance increased, the value of the field current will reduce. The coils in the shunt field are composed of many turns of small wire, resulting in low shunt field current and moderate armature current. In this method, the dc machine generator or motor is run as a motor at noload and losses of the machine are determined. Swinburnes test and speed control of dc shunt motor. In this method, we find the mechanical friction and windage and iron losses of the machine. Retardation test or running down test on dc machines. Hopkinsons test on two identical dc shunt machines and determination of the efficiency. Learners examine the operation of a dc shunt motor and its characteristics.
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. In a shunt motor, the field and armature windings are connected in parallel. The shunt motor is probably the most common dc motor used in industry today. Shunt dc motor the shunt motor is probably the most common dc motor used in industry today. Jun 02, 2015 retardation or running down test this method is applicable to shunt motors and generators and is used for finding stray losses. The open circuit characteristic curve shows the variation of induced emf as a function of field current at constant. The circuit diagram of a short shunt dc motor is shown in the diagram below. 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.
As the test is on noload, it is impossible to know whether commutation would be satisfactory at fullload and whether the temperature rise would be within the specified limits. Speed control of dc shunt motor for electric car use by. This paper discusses the speed and torque control of a shunt dc motor through matlab simulink simulations. Apparatus range type quantity 1 ammeter 020a mc 1 2 voltmeter 0300v mc 1 3 rheostat 1250. Test the shunt field continuity by measuring and recording the resistance of the shunt with an ohmmeter. Applications of dc machines motors and generators circuit. If you are looking for job then go check out interview questions page to. On occasion, a field regulator is contained within the field circuit of dc shunt motor for additional speed adjustment. In this method, the motor is put on the direct load by means of a belt and pulley arrangement. Determination of critical field resistance critical speed.
Speed control of dc shunt motor with field and armature rheostat control 79 2. C shunt motor power wound armature voltage armature current excitation speed 5hp shunt 220v. In this test we get total stray losses nothing but combination of. The dc shunt motor construction is the same as any type of dc motor. Dec 11, 2016 history of dc motor michael faraday u. Load test on singlephase transformer and three phase transformers.
Measurement of efficiency of shunt and series motors. To find the various parameters such as torque, input power, output power etc. The compound motors are used where higher starting torque and fairly. The connection diagram for dc shunt machine is shown in the figure below. Electrical machines for mechatronics laboratory 6 4 altering the armature voltage procedure using the lab equipments shown in figure 6. Equivalent circuit parameters are armature resistance ra 110 ohms, field resistance rf 2. When the armature of a dc motor rotates, emf induced is 115. Once the losses of the machine are known, its efficiency at any desired load can be determined in advance. This method enables the determination of losses without actually loading the machine. The machine under test is speeded up slightly beyond its normal speed and then supply is cut. To obtain speedtorque characteristics of dc series motor and dc shunt motor. As an example, a speed controller for a shunt motor built and tested by the author is discussed. In this post, we will discuss about various speed control methods of dc shunt motor.
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. May 24, 2015 a 10 hp 240 v dc shunt motor draws 38a of line current the field resistance is 170 ohms and the armature resistance is 0 4 ohms the rotational losses which include the brush contact loss are 100 w and the core losses are 5% of rated shaft output power d. Then, knowing the armature and shunt cu losses at a given load current, efficiency can be calculated. On the righthand end of the dynamometer is a clamp which locks the rotor and stator. Thanks for a2a the no load loss in dc shunt motor can be also referred as constant loss of dc shunt motor actually it is the core loss that takes place inside the armature winding but the armature current is very very negligible in no load condi. Dc shunt motor armature the parallel combination of two windings is connected across a common dc power supply. This is also well known that the dc machines can be used as a generator as well as as a motor, their is the difference of operation in both case i. Swinburns test 5 a dc series motor is best for driving a. Working principle of dc shunt motor, dc series motor and all other dc motors can be stated as follows.
The voltage applied to the motor may be reversed by backing the field current of generator through controller fc. In a shunt dc motor, the armature and field windings are connected in parallel. The dc shunt motor is 120vdc with rated speed of 1800 revolutions per minute. Mod01 lec35 lecture35testing of dc shunt motors youtube. Do search in wisdom jobs for dc motor job listings for full time and part time positions updated today. Dc motor is one of the rotary machines which makes use of electrical current and converts it to mechanical energy which can be used in many other functions or operations. The shunt winding has a large number of turns so that it has appreciable inductance. 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. In this article we are going to discuss about brake test on d. 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. Dec 05, 2017 a simple numerical just to get you guys understand the concepts.
Consequently, shunt motor will not usually run on a. 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. Speed control of dc shunt motor with field and armature. Brake test on dc shunt motor another method of testing the d. This motor can be constructed with the basic parts like field windings stator, a commutator and an armature rotor 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. This kind of winding is called shunt winding and the motor shunt dc motor creation and principle of operation of a shunt dc motor is same as any other dc motor. Components of the shunt motor are the armature, labeled a1 and a 2, and the field, labeled f1 and f2. C motor interview questions electrical engineering.
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