The initial current when starting the motor with the rated dc supply voltage. Limitations the speed of a dc compound motor can be easily controlled. View and download powerpoint presentations on speed control of a dc shunt motor ppt. As resistance increased, the value of the field current will reduce. It is desired to know the effects on armature current and speed of making various changes on the electrical side. And the armature winding is connected to external supply voltage hence it plays the role of current carrying. In the simple rheostatic control using only a series resistance, the voltage across the armature at noload is v. Types of dc motors dc motor are of 3 types they are 1. Speed vs torque characteristics of dc shunt motor from the above two characteristics of dc shunt motor, the torque developed and speed at various armature currents of dc shunt motor may be noted. Eeet103 lab10 speed torque characteristics of dc shunt motor. When a motor is designed in such a way that impedance of the aluminum conductor of the rotor is reduced, its efficiency is increased in a high speed range.
Lathes, drills, boring mills, shapers, spinning, and weaving machines series motor. Electrical machinel dc laboratory manual grietelectrical and. Dec 29, 2017 page 1 speed control of shunt dc motor characteristics of dc shunt motors page 2 speed control of shunt dc motor characteristics of dc shunt motors speed control of shunt dc motor effect of armature motors resistance speed control on a shunt motors torquespeed only used in applications in which. A universal motor is a special type of motor which is designed to run on either dc or single phase ac supply.
It has been shown earlier that the speed of a motor is given by the relation it is obvious that the speed can be controlled by varying i fluxpole, f flux control ii resistance ra of armature circuit rheostatic control and iii applied voltage v voltage con trol. The characteristics of a shunt motor reveal that it is an approximately constant speed motor. This motor gives features like easy reversing control, speed regulation, and starting torque is low. In this experiment the mechanical characteristics b and j will be determined. In a shunt motor, the field and armature windings are connected in parallel. Each type has unique operating characteristics and applications.
Analysis of the mechanical characteristics and determination. The backemf is given by lafifiaw, where if is the field current, ia is the. 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. These motors are generally series wound armature and field winding are in series, and hence produce high starting torque see characteristics of dc motors here. Pdf this paper discusses the speed and torque control of a shunt dc motor through matlab simulink simulations. And on the other hand, when designed to have a high impedance, the motor has an increased amount of torque. Dc machines are usually classified on the basis of their field excitation method. Motor characteristics series and shunt worldofmachines. Speed torque characteristics of separately excited. The compound motor has better speed characteristic than the series motor and better torque characteristics than the shunt motor. Mar 09, 2017 understanding the torque equation and the relationship between speed and torque is an important part of selecting and operating a dc motor dc motors are relatively simple machines. The dc shunt motor is 120vdc with rated speed of 1800. Therefore the voltage drops i a r a will be negligible as compared to the external supply. On the other hand, back emf reduces marginally more than that the speed of the shunt motor decreases to some extent with load.
In shunt dc motor we connect the field winding in parallel with the armature winding and we have a good speed regulation and also low starting torque which makes this motor suitable for beltdriven applications in industrial and automotive applications. Dc shunt motor armature the parallel combination of two windings is connected across a common dc power supply. The characteristics of shunt dc motor include the following. Because these two relationships are quite essential for understanding the characteristics of a dc motor. A comparison of the torquespeed cs of each of these type of machines is shown in figure 2. Electric drive system will operate in steady state at this speed, provided it is. Generally, three characteristic curves are considered important for dc motors which are, i torque vs. 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. In this type of dc motor, by a rising motor current, torque can be improved without reducing. Series wound dc motor in case of a series wound self excited dc motor or simply series wound dc motor, the entire armature current flows through the field winding as its connected in series to the armature.
Speed torque characteristics of dc motors by portescap. Dc motor fault zone analysis is a vital part of any dc motor maintenance program. Jul 09, 2017 panel for plotting the speed torque characteristics of a dc shunt motor. From the speed useful output power curve it is seen that the shunt motor has a definite speed at no load. Dec 11, 2016 history of dc motor michael faraday u. Equivalent circuit parameters are armature resistance ra 110 ohms, field resistance rf 2.
Dec 29, 2015 therefore, the starting torque of a dc shunt motor is low, meaning that the shaft load must be small at startup. The torquespeed characteristic for the shunt motor block model is related to the parameters in the preceding figure. When a current carrying conductor is placed in a magnetic field, it experiences a force. A dc motors speed and torque characteristics vary according to three different magnetization sources, separately excited field, selfexcited field or permanentfield, which are used selectively to control the motor over the mechanical loads range. Dc motor model with electrical and torque characteristics. The speed of the separately excited dc motor drops with load, the net drop being about 5%10% of the base speed at full load. The graph shows the torquespeed characteristics of a shunt dc motor. A dc machine 12 kw, 100 v, rpm is connected to a 100 v dc supply and is operated as a dc shunt motor. The speedtorque characteristics of the four types, i. Speed control of dc shunt motor with field and armature rheostat control 79 2. Therefore the voltage drops i a r a will be negligible as compared to the external supply voltage v. Speed of a dc motor can be varied by varying flux, armature resistance or applied voltage.
Why is the dc series motor rpm higher than the dc shunt motor. Find powerpoint presentations and slides using the power of, find free presentations research about speed control of a dc shunt motor ppt. Working principle of dc shunt motor your electrical guide. Speed control of dc shunt motor your electrical guide.
This is experiment 10 on the effect of load torque on the speed of a dc shunt motor. The performance curves are taken from the scope function of simulink. Joint speed torque characteristics equilibrium speed of motorload system can be obtained when motor torque equals the load torque. Whenever a current is supplied by means of a dc source, flux is produced which in turn interacts with the armature flux to produce a unidirectional torque. By varying the values of series and shunt resistances the speed torque characteristics can be made to have any desired shape. A shunt dc motor connects the armature and field windings in parallel or shunt with a common d. These curves are also known as performance curves of a motor. Open circuit and load characteristics of dc shunt generatorcritical resistance and critical speed. Jun 12, 2019 before discussing the characteristics of dc motors, let us recall the expression of speed and torque of a dc motor. So from these 2 equations, we can conclude that speed and torque both has a linear relationship. Working principle of dc shunt motor, dc series motor and all other dc motors can be stated as follows. At noload condition, the motor runs at rpm and the armature current takes 6 a. This dc motor is upturned by the turn around the motor connections like a series motor.
Torque equation and the relationship with dc motors. Characteristics of dc motor shunt, series, and compound. Understanding the torque equation and the relationship between speed and torque is an important part of selecting and operating a dc motor dc motors are relatively simple machines. The shunt wound dc motor is a constant speed motor, as the speed does not vary here with the variation of mechanical load on the output. Feb 07, 2017 variations of speed can be discussed with the formula n. And when supply voltage is constant, speed is inversely proportional to the load on the motor. Eb change in eb for various load currents is small, so may be neglected for the time being. Motor characteristics electrical engineering assignment. Draw the speedtorque characteristics of dc shunt motor and series motor. Speed control of dc shunt motor with field and armature. In a series dc motor, the armature current, the field current, and the line current are all the same.
Panel for plotting the speedtorque characteristics of a dc shunt motor. Characteristics of induction motors nidec corporation. This cyclic load causes a continuous variation of the motor s speed because of the very rapid response of induction. In contrast, for a serieswound dc motor, torque increases as the square of armature current. Because of stiction, the speed torque characteristics of the load is modified near to zero speed.
Characteristics of shunt motors 30 the speed n of the motor decrease slightly with the increase in torque since the drop in speed from no load to full load is very small, a shunt motor may be taken as a constant speed motor for all practical purposes torque speed curve. Speed torque characteristics of dc motors example 11 q. The armatures torque increases as the motor gains speed due to the fact that the shunt motors torque is directly proportional to the armature current. The basic behavior of a series dc motor is due to the fact that the flux is directly proportional to the armature current, at. Characteristics of dc shunt motor, dc series motor, dc. This paper discusses the speed and torque control of a shunt dc motor through matlab simulink simulations. Determination of power relationship for dc motor 534 hao hu procedia engineering 15 2011 531 a 535 3. To obtain the performance characteristics of a dc shunt motor by load test.
We know the mechanical power developed in the armature of the motor is the product of back emf and armature current. The speedtorque characteristics of a pm dc motor are quite linear. Induced torque in a series dc motor the terminal characteristics of a series dc motor is very different from that of the shunt dc motor. The shunt motor block represents the electrical and torque characteristics of a shunt motor using the following equivalent circuit model. Speedtorque characteristics from the above two characteristics of dc shunt motor, the torque developed and speed at various armature currents of dc shunt motor may be noted. Selfexcited field motors can be series, shunt, or compound wound connected to the armature. Swinburnes test and speed control of dc shunt motor. Though there are separate branches for the flow of.
Universal motor construction, working and characteristics. Characteristics of dc motors through equations eeebooks4u. Types of dc motors and their applications electrical4u. Therefore, the starting torque of a dc shunt motor is low, meaning that the shaft load must be small at startup. The torque load on the gearbox as well as on the prime mover, as discussed in previous sections, is widely fluctuating during the pumping cycle. Speed torque characteristics of dc shunt motor youtube. When a motor is designed in such a way that impedance of the aluminum conductor of the rotor is reduced, its efficiency is increased in a highspeed range.
Torquespeed characteristic of a shunt or separately excited dc motor ind then, with constant v t, otherwise it affect the torquespeed curve this equation is a straight line with a negative slope. The dc shunt motor is 120vdc with rated speed of 1800 revolutions per minute. Learn about the speedtorque characteristics of dc motors from portescap application engineer, faisal pawaskar. Gabor takacs phd, in suckerrod pumping handbook, 2015. This characteristic is also called as mechanical characteristic. Oct 29, 2015 learn about the speed torque characteristics of dc motors from portescap application engineer, faisal pawaskar.
When the load current ia falls to a small value, speed becomes dangerously high. Factors controlling motor speed electric equipment. Before discussing the speed control of dc shunt motor, we have to find the factors affecting the speed of a dc motor. Torque equation of dc motor for series, shunt and compound.
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. Project ideas electrical electronics robotics technology download projects list. From the above two characteristics of dc series motor, it can be found that when speed is high, torque is low and vice versa. The power flow in a dc generator or motor is represented in fig. In the case of a dc motor, the magnetic field is produced by the field winding. The dc motor block uses manufacturer datasheet parameters, which specify the motor as delivering 10w mechanical power at 2500 rpm and noload speed as 4000 rpm when run from a 12v dc supply. 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. O dc series motor variations of speed can be deduced from the formula n. Load characteristics of dc compound generator with differential and cumulativeconnections. Construction, circuit diagram, and its applications.
Thus the speed of dc motor is given by, eb v i a r a. The main properties of individual motors, from this diagram, may be summarised as under. Dc starter face plate type suitable for above motor. When applied voltage v is changed, as shown in figure 2, torque rotating speed characteristics will be proportional to the value for v, but current torque characteristics will only change very slightly. The speed torque characteristics of the four types, i. Torque speed characteristics of shunt motor basically, in a shunt motor, the field winding is connected in parallel to the armature winding. In this article, speed torque characteristics are discussed in detail. This dc motor works at a fixed speed once the voltage supply is set. This curve is drawn between the speed of the motor and armature current with various amps as shown in the fig. But, the characteristics of speedtorque are more linear as well as conventional in these types of motors. These are explained below for each type of dc motor. 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. The pmdc motor characteristics are related to the dc shunt motor characteristic in terms of speed, torque, as well as armature current.
A series motor should never be started without some mechanical load why. 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 torque speed characteristic for the shunt motor block model is related to the parameters in the preceding figure. The motor can be connected so that the shunt field and the series fields are in the same direction. Hence a series motor should never be started without some mechanical load. That is why, universal motors generally comes built into the device they are meant to drive. These characteristics enable the operator to perform a wide variety of tasks. As the load gets very large, the series flux becomes quite important and the torquespeed curve begins to look like a series motors cs. 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.
The dc shunt motor construction is the same as any type of dc motor. If these values are plotted, the graph representing the variation of speed with torque developed is obtained. 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. Shunt motor with electrical and torque characteristics. Since they are connected in parallel, the armature and field windings are exposed to the same supply voltage. In a dc shunt motor, torque is proportional to armature current as shown in the torque equation below. These methods as applied to shunt, compound and series motors will be.
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