Since they are connected in parallel, the armature and field windings are exposed to the same supply voltage. While in the noload test we shall be exciting the armature independently the load test as the name suggests shall be carried out in shunt. On occasion, a field regulator is contained within the field circuit of dc shunt motor for additional speed adjustment. In this paper will be studying about the various speed control methods of a dc series motor. Jan 14, 2018 load test on dc shunt motor and to find efficiency precautions. Calculate the rotational losses under this operating condition.
To control the speed of a dc shunt motor by the method of a. Lathes, drills, boring mills, shapers, spinning, and weaving machines series motor. Dc shunt motor should be started and stopped under no load condition. The voltage applied to the motor may be reversed by backing the field current of generator through controller fc. The shunt winding has a large number of turns so that it has appreciable inductance. Pdf this paper discusses the speed and torque control of a shunt dc motor through matlab simulink simulations. Speed control of dc shunt motor by armature and field control. Since the shunt field coil is made of fine wire, it cannot produce the large current for starting like the. Dc shunt motor theory quiz questions electrician practice tests. Torque control of a shunt wound and dc motor of an electric. If i remove power to the field winding, then shouldnt the motor slows down because the. In this post, we will discuss about various speed control methods of dc shunt motor. To determine the efficiency of the given dc shunt motor by conducting load test. 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.
A good material for the poles of a pmdc motor should have the apposite of the above. Speed control of dc shunt motor your electrical guide. A dc motor draws more current with a mechanical load applied to its shaft because the cemf is reduced with the speed. To control the speed of dc shunt motor using field control method.
This method is only applicable when we want speed which is higher than the normal speed of the motor. Depending on the parameter being controlled, methods of speed control of shunt dc motor are classified as follows. Armature rheostat should be kept in the maximum resistance position at the time of starting and stopping the motor. Relation between torque and speed in a dc motor say dc shunt.
In mechanical system, speed varies with number of task so speed control is necessary to do mechanical work in a proper way. Speed variation is accomplished by means of a variable resistance inserted in series with the shunt. Before discussing the speed control of dc shunt motor, we have to find the factors affecting the speed of a dc motor. Dc shunt motor but field rheostat control method is most reliable, economic and independent of load on the motor. No load test on dc shunt generator 1 connect the circuit as shown in figure 1 with switches s1 and s2 open. Once the motor reaches its full speed, it remains constant.
Boston gear offers a wide range of odp open drip proof ac motors, including brake motors. In this method, a brake is applied to a watercooled pulley mounted on the motor shaft as shown in fig. Field rheostat control of dc shunt motor in this method. It is supplied with one ms powder coated electrical panel fitted with high insulation bakelite sheet. Speed of a shunt dc motor can be easily controlled. A shuntwound motor has decreasing torque as speed increases. A shunt wound motor has decreasing torque as speed increases. Reduced field strength will cause high armature currents. Speed control, armature, rpm field control, dc motor, series, parallel, voltage, and current i. To draw the performance characteristics of the given dc shunt motor by conducting load test. To find the various parameters such as torque, input power, output power etc. It is a machine which converts electrical energy into mechanical energy.
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. Hopkinsons test is another useful method of testing the efficiency of a dc machine. In a field loss event, why does a shunt wound dc motor run away. Speed control methods of dc shunt motor my tech info.
In a shunt dc motor, the armature and field windings are connected in parallel. The principle of the dc motor relies on the concept of commutation. The machine used in this experiment is a representative of an industrial dc motor or generator with a rated power of tens of kilowatts. Dc motors although ac motors are used in most of the cases, dc motors have many applications and used for multipurpose applications. Shunt motor is a special type of dc motor which runs at. From my understand of electric motor, the armature spins because its magnetic field pushespulls against the field windings magnetic field. A shuntwound motor is a dc motor in which the wound electromagnetic rotor field is in parallel not series with the armature. Relation between torque and speed in a dc motorsay dc. Electrical machinel dc laboratory manual grietelectrical and. Field rheostat should be kept in the minimum position. Experiment 6 shunt dc motor ii objective to study the behavior of a shunt dc motor speed when the field resistance is altered. Shunt dc motors electrical calculations and induction motor.
As the rotating speed of dc shunt motor depends on armature voltage and field current applied to the shunt motor, therefore, these two process parameters were varied during. To study the behavior of a shunt dc motor speed when the armature voltage is altered. This type of motor has good speed regulation even as the load varies, but does not have the starting torque of a series dc motor. However, the voltage differential increases and causes an increase of input current to the motor. Torque control of a shunt wound and dc motor of an electric vehicle by means of continuous field control and stepwise adjustment of the armature voltage. However, short term currents that occur in motorstarting or enginecranking can exceed the shunt rating by a factor of 2 or more without damage to the shunt or meter. Test the shunt field continuity by measuring and recording the resistance of the shunt with an ohmmeter. To control the speed of dc shunt motor using armature control method. Dc motor principle a machine that converts dc power into mechanical energy is known as dc motor. The aim of this this paper is to describe the principle of.
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. Load test on dc shunt motor offered by unicon instruments, a leading supplier of dc shunt motor in sadar bazar, ambala, haryana. One end of the rope is fixed to the floor via a spring balance s and a known mass is suspended at the other. In this method, an increase in controlling resistance reduces the field current with a consequent reduction in flux and. Continuous currents should not exceed 80% of the shunt rating. Circuit diagram load test on dc shunt motor figure 1. A compound dc motor connects the armature and fields windings in a shunt and a series combination to give it characteristics of both a shunt and a series dc motor. 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. Q what happens if dc supply is applied to the transformer. Introduction dc series motor a dc motor, whose field winding is excited by the current produced by itself, is called selfexcited. Torque control of a shunt wound and dc motor of an electric vehicle by means of continuous field control and stepwise adjustment of the armature voltage citation for published version apa. To obtain the performance characteristics of a dc shunt motor by load test.
Dc motors plays an important role in energy conversion process. Notice the shunt coil is identified as a coil of fine wire with many turns that is connected in parallel shunt with the armature. Consequently, shunt motor will not usually run on a. This commutator and brush connection always keep the direction of the current and the direction of the magnetic field consistent. When a shunt dc motor reaches its full speed, the armature current is directly related to the motor load. A shunt dc motor connects the armature and field windings in parallel or shunt with a common d. Torque control of a shunt wound and dc motor of an. Dc starter face plate type suitable for above motor. I have a doubt on relation between torque and speed in a dc motor. A stab is shaped piece of metal that makes up a certain type of wound rotor. Speed control method of dc series motor shubham sharma, simran singh oberoi, siddharth nair ece dept, dronacharya college of engg abstract. In dc series motor the field windings are connected to the armature in series so that whole current flows. State two ways by which the output polarity of a separatelyexcited dc shunt generator can be changed 2. Load test on dc shunt motor and to find efficiency precautions.
Field rheostat should be kept in the minimum resistance position at the time of starting and stopping the motor. One of these two machines is operated as a generator to supply the mechanical power to the motor. By means of this method, the motor can be worked at any speed up to its maximum speed. Armature resistance control and field flux control the dc motor converts the mechanical power into dc electrical power. An efficient method for speed control of dc shunt motor. Though there are separate branches for the flow of armature current and field current. One of the most important features of the dc motor is that their speed can easily be control according to the requirement by using simple methods. It is a full load test and it requires two identical machines which are coupled to each other. Dc motors calculating efficiency all about circuits. The dc generator as we know can be either separately excited or self excited in shunt. The dc shunt motor is 120vdc with rated speed of 1800 revolutions per minute. In electrical terminology, a parallel connection is termed shunt. To conduct a load test on dc shunt motor and to find its efficiency. In this post we had collected some of the most frequently asked electrical machines 1 viva questions with detailed answers.
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. Speed control of dc motor shunt type aim a to study the speed control of dc motor below the normal range by armature resistance control and to plot speed vs armature voltage, characteristic. The company was incorporated in 1954 and is registered with indiamart. Ia sience flux constant torque proportional to ia so when armature. A dc motor must have 100% field strength to produce its maximum torque and to keep the armature amperage within proper limits. As we know that if we increase load the armature speed will decrease so that back emf also decrease or say armature current will increase and we know that torque depends on armature current ia in a dc shunt motor so the flux could be constant torque proportional to flux. This type of winding is called shunt winding and the motor shunt dc motor.
This paper discusses the speed and torque control of a shunt dc motor through matlab simulink simulations. Analog ammeter and voltmeter are provided on the front panel sheet. The field winding is connected in parallel with the armature. Torque control of a shunt wound and dc motor of an electric vehicle by means of. Noload speed of which of the following motor will be highest. A shunt wound motor is a dc motor in which the wound electromagnetic rotor field is in parallel not series with the armature. These motors are offered in cface models for mounting to our enclosed gear drives, and they are available in 16 20 hp and cover voltage ranges from 115 vac to 460 vac.
Its operation is based on the principle that when a current carrying conductor is placed in a. Therefore the voltage drops i a r a will be negligible as compared to the external supply voltage v. If a dc generator delivers 180 w to a load, what is. A 10 hp, 200v dc shunt motor has an armature resistance of 1 ohm and shunt field resistance of 100 ohms. If a dc generator delivers 180 w to a load, what is the minimum mechanical power in watts. To conduct load test on dc motor with shunt excitation and plot the typical characteristics.
To study the behavior of a shunt dc motor speed when a. 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. A shunt motor has slightly different operating characteristics than a series motor. Speed control of dc shunt motor with field and armature. Speed control of dc shunt motor so by varying one of these parameters, it is possible to change the speed of dc shunt motor.
What is the difference between a dc shunt and a series motor. This motor is used when both a high starting torque and good speed regulation is needed. Since load is very small in a shunt motor, armature current is also very low. Dec 25, 2017 in this video you will learn about speed control of dc shunt motor now you can join our whatsapp group.
Load test on dc shunt motor unicon instruments exporter. At noload, the motor draws 3a from the 200v supply and and runs at 1500 rmin. Thus the speed of dc motor is given by, eb v i a r a. Practice dismantling and assembling in dc shunt motor. 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. C is applied to a shunt motor, the large inductive reactance of shunt winding will reduce the field current too much. The characteristics of a shunt motor reveal that it is an approximately constant speed motor. Aug 03, 2018 hopkinsons test is another useful method of testing the efficiency of a dc machine. 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. Field loss in a shunt wound dc motor physics forums.
We believe that these faqs will be useful for your practical exams and interviews as well. To perform open circuit test and short circuit test on a. Dc shunt motor speed control armature control method. Parts and principle of operation of a shunt dc motor. Title of the experiment page no 7 retardation test on dc shunt motor. Load test on dc shunt motor to draw speed torque and horse power efficiency characteristics.
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