It is a machine which converts electrical energy into mechanical energy. An electrical machines and simulations textbook csun. Describe what happens in a serieswound motor when a mechanical load is placed on the motor, causing it to slow down and the counteremf to decrease. There are 3 main types of dc motor that are available. Notice the shunt coil is identified as a coil of fine wire with many turns that is connected in parallel shunt with the armature. Set the inserted field resistance and the inserted armature resistance to their maximum values. The motor must accelerate softly, brake smoothly and reliably, and stop with pinpoint. This commutator and brush connection always keep the direction of the current and the direction of the magnetic field consistent.
The purpose of this load test is to test which is used to test the performance. Starting, braking and positioning with threephase cage induction. A shuntwound motor is a dc motor in which the wound electromagnetic rotor field is in parallel not series with the armature. The machine is running as a motor at rated voltage and speed. Dc shunt wound motor application and operation engineers. Lathes, drills, boring mills, shapers, spinning, and weaving machines series motor.
Speed control of dc shunt motor with field and armature. 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. Because loading will be applied directly on shaft of the motor by means of a belt and pulley arrangement. In electrical terminology, a parallel connection is termed shunt. In a shunt dc motor, the armature and field windings are linked in parallel. Though there are separate branches for the flow of armature current and field current. In this article we are going to discuss about brake test on d. The shunt winding has a large number of turns so that it has appreciable inductance. A shuntwound dc motor has a decreasing torque when speed increases. Therefore the voltage drops i a r a will be negligible as compared to the external supply voltage v. 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. In this paper will be studying about the various speed control methods of a dc series motor. Speed control method of dc series motor shubham sharma, simran singh oberoi, siddharth nair ece dept, dronacharya college of engg abstract.
Speed control method of dc series motor shubham sharma, simran singh oberoi, siddharth nair ece dept, dronacharya college of engg. A shuntwound dc motor with the field coils and rotor. In this post, we will discuss about various speed control methods of dc shunt motor. A dc shunt motor 50hp, 250v is connected to a 230v supply and delivers power to a load drawing an armature current of 200a and running at a speed of 1200rpm, given ra0. Generally, this test can be done for the low rated dc machines. Parts and principle of operation of a shunt dc motor. In this method, a brake is applied to a watercooled pulley mounted on the motor shaft as shown in fig. Nearly all types of dc motors have some internal mechanism, either electromechanical or electronic, to periodically change the direction of current in part of the motor. The dc shunt motor is 120vdc with rated speed of 1800 revolutions per minute.
By means of this method, the motor can be worked at any speed up to its maximum speed. Dc shunt wound motor application and operation engineers edge. 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. The selfexcited motors are further classified as shunt wound or shunt motor, series wound or series motor and compound wound or compound motor. Riosque y zack special edition hd recommended for you. C is applied to a shunt motor, the large inductive reactance of shunt winding will reduce the field current too much. 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. 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. A shunt wound dc motor has a decreasing torque when speed increases. Dc motors are transducers because they convert electrical power pin into mechanical. Consider the air gap flux remains fixed at its value at no load. A dc motor is any of a class of rotary electrical motors that converts direct current electrical energy into mechanical energy. Load test was conducted on the dc shunt motor to find. These terms relate to the type of connection of the field windings with respect to the armature circuit.
Brake test on dc shunt motor electric motor electrical engineering. A shunt wound motor is a dc motor in which the wound electromagnetic rotor field is in parallel not series with the armature. In the case of a dc motor, the magnetic field is produced by the field winding. This motor is used when both a high starting torque and good speed regulation is needed. As the name implies selfexcited, hence, in this type of motor, the current in the windings is supplied by the machine or motor itself. This type of winding is called shunt winding and the motor shunt dc motor. Relation between torque and speed in a dc motorsay dc. Measurement of efficiency of shunt and series motors. To obtain the performance characteristics of a dc shunt motor by load test. A shunt wound motor has decreasing torque as speed increases. When the motor is running, the rotor develops an emf e. No,in dc motors when ac given to the armature it converts it into dc and produces a stationary armature magnetic field,if ac is aplied o the shunt field it will produce alternating field which will produce torque in opposite torque in alternate half cycles so avg. Working principle of dc shunt motor, dc series motor and all other dc motors can be stated as follows.
A dc motor must have 100% field strength to produce its maximum torque and to keep the armature amperage within proper limits. Before discussing the speed control of dc shunt motor, we have to find the factors affecting the speed of a dc motor. On the other hand, back emf reduces marginally more than that the. Speed control methods of dc shunt motor my tech info. A good material for the poles of a pmdc motor should have the apposite of the above. Test the shunt field continuity by measuring and recording the resistance of the shunt with an ohmmeter. A stab is shaped piece of metal that makes up a certain type of wound rotor. What is a dc shunt motor and its advantage and disadvantage. A dc series motor will have its field windings connected in series with the armature. The decreasing torque vs speed is caused by the armature resistance voltage drop and armature reaction. A shuntwound motor has decreasing torque as speed increases.
Since they are connected in parallel, the armature and field windings are exposed to the same supply voltage. Electrical machines for mechatronics laboratory 6 4 altering the armature voltage procedure using the lab equipments shown in figure 6. The aim of this this paper is to describe the principle of. 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. To know how to estimate and predict efficiency of a d. 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. Direct method of testing of dc machine, also known as brake test. Since load is very small in a shunt motor, armature current is also very low. The following readings are obtained when doing a load test on a dc motor using brake drum. Shunt motor is a special type of dc motor which runs at. To find the various parameters such as torque, input power, output power etc. This paper shows measurement of efficiency of dc shunt and series motor. Speed control of dc shunt motor so by varying one of these parameters, it is possible to change the speed of dc shunt motor.
A dc motor, whose field winding is excited by the current produced by itself, is called selfexcited. The brake test is the one kind of load test on dc shunt motor. I have a doubt on relation between torque and speed in a dc motor. The most common types rely on the forces produced by magnetic fields. 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. In electrical terminology, a parallel connection is called shunt. Scribd is the worlds largest social reading and publishing site. Brake test on dc shunt motor electric motor electrical. And the armature winding is connected to external supply voltage hence it plays the role of current carrying conductor. Using an adjustable torque load such as a small particle brake or an. 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. 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.
Set upconnections, rotation reversal, speed control, load. Field armature motor contrast this behavior against that of a permanent. In mechanical system, speed varies with number of task so speed control is necessary to do mechanical work in a proper way. Dc motors were widely used in whole over the world. In this paper discussed about load test of dc series and shunt motor.
A belt around the air cooled pulley has its end attached to the spring balance s1 and s2. To draw the performance characteristics of the given dc shunt motor by conducting load test. Thus the speed of dc motor is given by, eb v i a r a. 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. 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. When a shunt dc motor reaches its full speed, the armature current is directly related to the motor load. Reduced field strength will cause high armature currents. On occasion, a field regulator is contained within the field circuit of dc shunt motor for additional speed adjustment. Speed control of dc shunt motor your electrical guide. Torque control of a shunt wound and dc motor of an. 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. Working principle of dc shunt motor your electrical guide.
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. Brake test is also a method of finding efficiency of dc motors. Dc shunt motor theory quiz questions electrician practice tests. The connection diagram for dc shunt machine is shown in the figure below. The principle of the dc motor relies on the concept of commutation. Shunt dc motors electrical calculations and induction 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. First, one is separately excited dc motor and selfexcited dc 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. Types of dc motor a direct current motor, dc is named according to the connection of the field winding with the armature. One end of the rope is fixed to the floor via a spring balance s and a known mass is suspended at the other. Dc machines can be tested by three different methods namely direct method, indirect method and regenerative method. The characteristics of a shunt motor reveal that it is an approximately constant speed motor.
Selfexcited dc motor is further divided into shunt wound, and series wound motor. Depending on the parameter being controlled, methods of speed control of shunt dc motor are classified as follows. Open circuit and short circuit tests in transformers. To determine the efficiency of the given dc shunt motor by conducting load test. 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. A shuntwound dc motor with the field coils and rotor connected in parallel fig operates from a 120v dc power line.
Consequently, shunt motor will not usually run on a. This can be proudly known as workhorse of industrial systems. Mar 14, 2016 laboratory explanation of break test on dc shunt motor. Dc starter face plate type suitable for above motor. When a current carrying conductor is placed in a magnetic field, it experiences a force. Brake test on dc shunt motor free download as word doc. Title of the experiment page no 7 retardation test on dc shunt motor. And the armature winding is connected to external supply voltage hence it. A series generator having combine armature and field resistance of 0. A dc motor draws more current with a mechanical load applied to its shaft because the cemf is reduced with the speed.
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 voltage applied to the motor may be reversed by backing the field current of generator through controller fc. Brake test also called as direct loading test of testing the motor. The core losses are 200 w, and the mechanical losses are 240 w at full load.