In a compound dc motor, the series field flux and shunt field flux may oppose each other or may support each other depending on the relative connection between these two fields. When you set the model parameterization parameter to by equivalent circuit parameters, you specify the equivalent circuit parameters for this model. Equivalent circuit parameters are armature resistance ra 110 ohms, field resistance rf 2. At light loads, the series field has a very small effect, so the motor behaves approximately as a shunt d. The characteristics of a shunt motor reveal that it is an approximately constant speed motor. In this post, we will look into the characteristics of a dc series motor. This motor is used when both a high starting torque and good speed regulation is needed. Although the field current remains practically constant, yet the field flux becomes slightly weaker at heavy loads, due to armature reaction, hence the curve bends slightly bends at heavy loads. 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. C ompoundw ound m otor c haracteristics compoundwound dc motors combination of the shunt wound and series wound types combines the characteristics of both. To discover the characteristic change in torque output of a dc shunt motor as it. 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. Characteristics of dc series motor studyelectrical.
Dc motor fault zone analysis is a vital part of any dc motor maintenance program. On the other hand, back emf reduces marginally more than that the speed of the shunt motor decreases to some extent with load. This motor can be constructed with the basic parts like field windings stator, a commutator and an armature rotor. When its field magnets are excited and its armature conductors are supplied with current from the supply mains, they experience a force tending to rotate the armature.
This excessive current would operate the overload device, disconnect the motor from the supply, and thus protect the motor. Jun 12, 2019 the compound motor is a motor which has both shunt and series field. A same dc machine can be used as a motor or generator. In electrical terminology, a parallel circuit is often referred to as a shunt. The diagram of short shunt type motor is illustrated below. That is the reason behind naming it a dc shunt motor. Shunt motor has different speed characteristics from a series motor. Therefore, torque current characteristics of a shunt motor is a straight line passing through the origin. In a shunt motor, the field and armature windings are connected in parallel. The characteristic show that dc shunt motor speed remains almost constant from noload i a. If applied voltage v is kept constant, the field current will remain constant, hence. Lathes, drills, boring mills, shapers, spinning, and weaving machines series motor.
The shunt motor block represents the electrical and torque characteristics of a shunt motor using the following equivalent circuit model. A characteristic of series motors is the motor develops a large amount of starting torque. Swinburnes test and speed control of dc shunt motor. Characteristics of dc compound motor dc compound motors have both series as well as shunt winding. However, speed varies widely between no load and full load. Pdf analysis of the mechanical characteristics and determination. Fig shows the connections of a shunt wound generator. A dc motor may have both field windings wound on the same pole. Speed control of dc shunt motor with field and armature. If the shunt field winding is connected in parallel to the load, it is called the longshunt connection. The graph shows the torquespeed characteristics of a shunt dc motor. What is a dc shunt motor and its advantage and disadvantage.
If these values are plotted, the graph representing the variation of speed with torque developed is obtained. If we ignore the core saturation, the starting torque of the series motor is. 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. To discover the characteristic change in speed of a dc series motor as it is. Pdf with good characteristics and performance, the separately or shunt excited dc motor is widely used in the laboratory and on the precision machine. Since they are connected in parallel, the armature and field windings are exposed to the same supply voltage. When the direction of shunt field flux and series field flux is the same that means flux of one. In a dc compound motor both series and shunt fields are present.
Generally, three characteristic curves are considered important for dc motors which are, i torque vs. This modification may be used if stable low speed operation is required. 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. 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. When a shunt dc motor reaches its full speed, the armature current is directly related to the motor load. It is the difference in the noload and the ratedload speed divided by the noload speed. The dc shunt wound motor, running on direct current, has its field windings placed in parallel to the armature. The polarity direction of the series field is also important. Because these two relationships are quite essential for understanding the characteristics of a dc motor. Shunt motor with electrical and torque characteristics. Open circuit and load characteristics of dc shunt generatorcritical resistance and critical speed. Series wound dc motor or dc series motor electrical4u.
When you set the model parameterization parameter to, you specify the equivalent circuit parameters for this model. 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. Same voltage is applied to both shunt winding and armature in this motor. Characteristics of dc generator shunt dc generator. As resistance increased, the value of the field current will reduce. For their constant speed characteristics, shunt dc motors are used in fixed speed applications such. Speed control of dc shunt motor with field and armature rheostat control 79 2. 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.
From the speeduseful output power curve it is seen that the shunt motor has a definite speed at no load. The speed regulation of a shunt motor is almost identical with the voltage regulation of a shunt generator. Increasing the shunt motor speed by reducing armature resistance armature control reduces the running cost but increases the efficiency from its original values to. The performance of any motor can be judged from its characteristic curves known as motor characteristics. Hence, dc motors in which the armature and field windings are connected in parallel are referred to as dc shunt motors. Power supply module 120vac, 0120vdc ems 8821 dc metering module 200v, 5a ems 8412 dc motor generator module ems 8211 connections leads ems 8941. 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. Dc series motors are used where high starting torque required. In a compound motor, if series and shunt windings are connected such that series flux is in direction as that of the shunt flux then the motor is said to be cumulatively compounded. Generally used where severe starting conditions are met and constant speed is required at the same time. A dc series motor is one type of dc motor in which field winding is connected in series with the armature winding. Each type has unique operating characteristics and applications.
The performance of the motor is determined by the relative strengths of the series, shunt or separately excited field windings and by the orientation of the fluxes produced by them. Shunt motors are widely used beceuse of their constant speed characteristics. These characteristics enable the operator to perform a wide variety of tasks. Characteristics of compound motor 34 compound motor characteristics are intermediate between the shunt and series motors torquespeed of compound motor shows that the motor has high starting torque together with a safe noload speed. In a series dc motor the field is connected in series with the armature. Load characteristics of dc compound generator with differential and cumulativeconnections. 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. According to characteristics of dc motor, motors are used in the application. In electrical terms, parallel is generally denoted as shunt. The basic behavior of a series dc motor is due to the fact that the flux is directly proportional to the armature current, at least until saturation is reached. Mar 23, 2019 a series wound dc motor like in the case of shunt wound dc motor or compound wound dc motor falls under the category of selfexcited dc motors, and it gets its name from the fact that the field winding in this case is connected internally in series to the armature. 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. The field is wound with a few turns of large wire because it must carry the full armature current. The shortshunt connection, where the shunt field is connected in parallel to the armature, is shown in figure 4.
The relationship between and current and voltage is expressed as. The dc shunt motor construction is the same as any type of dc motor. These curves are also known as performance curves of a motor. Construction and principle of operation of the shunt dc motor. Sep 30, 2017 typical speedtorque characteristics are shown in fig. Jul 04, 20 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. Characteristics may be varied by varying the combination of the two windings. This parallel configuration allows independent path of current for field winding and armature.
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