On occasion, a field regulator is contained within the field circuit of dc shunt motor for additional speed adjustment. The field current is adjusted to normal value corresponding to the normal speed. Measurement of efficiency of shunt and series motors. A 240v dc shunt dc motor has an armature resistance of 0. We will go through all the possible loose connections for the shunt dc motor. One of them causes the motor to completely loose speed control and. Analog ammeter and voltmeter are provided on the front panel sheet. Determination of critical field resistance critical speed. Speed control method of dc series motor shubham sharma, simran singh oberoi, siddharth nair ece dept, dronacharya college of engg. A dc motor is any of a class of rotary electrical motors that converts direct current electrical energy into mechanical energy.
Therefore the voltage drops i a r a will be negligible as compared to the external supply voltage v. The voltage applied to the motor may be reversed by backing the field current of generator through controller fc. Motor connections your motor will be internally connected according to one of the diagrams shown below. Use figure 1 if your motor has a single voltage shunt field. Before discussing the speed control of dc shunt motor, we have to find the factors affecting the speed of a dc motor. Shunt motor with electrical and torque characteristics.
The various applications of dc shunt motor are in lathe machines, centrifugal pumps, fans, blowers, conveyors, lifts, weaving machine, spinning machines, etc. All motors have been sized for roughly the same mechanical power rating. The open circuit characteristic curve shows the variation of induced emf as a function of field current at constant. Notice the shunt coil is identified as a coil of fine wire with many turns that is connected in parallel shunt with the armature. In electrical terminology, a parallel connection is termed shunt. The circuit is connected as shown in the circuit diagram. It is supplied with one ms powder coated electrical panel fitted with high insulation bakelite sheet. Dc motors were widely used in whole over the world. Electrical machinel dc laboratory manual grietelectrical and. Set the inserted field resistance and the inserted armature resistance to their maximum values. The characteristics of a shunt motor reveal that it is an approximately constant speed motor. These connections are in accordance with nema mg1 and american standards publication 06. 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.
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. By means of this method, the motor can be worked at any speed up to its maximum speed. To draw the performance characteristics of the given dc shunt motor by conducting load test. No load test on dc shunt generator 1 connect the circuit as shown in figure 1 with switches s1 and s2 open.
A comparison of the torquespeed characteristics for five different motor types. The machine is running as a motor at rated voltage and speed. A shunt excited dc motors terminal voltage is 500 v. The most common types rely on the forces produced by magnetic fields. This video will walk you through the connections for a shunt dc motor and demonstrate how it runs without a physical load connected to the shaft of the motor. These terms relate to the type of connection of the field windings with respect to the armature circuit. Lathes, drills, boring mills, shapers, spinning, and weaving machines series motor. 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. A shuntwound motor is a dc motor in which the wound electromagnetic rotor field is in parallel not series with the armature. This type of winding is called shunt winding and the motor shunt dc motor. Load test on dc shunt motor, dc shunt wound motor, direct. Speed control of dc shunt motor with field and armature rheostat control 79 2.
The shunt motors are used where constant speed is required and starting conditions are not severe. The dc shunt motor is 120vdc with rated speed of 1800 revolutions per minute. Use figure 2 if your motor has a dual voltage shunt field. Electrical machines for mechatronics laboratory 6 4 altering the armature voltage procedure using the lab equipments shown in figure 6. To determine the efficiency of the given dc shunt motor by conducting load test. This paper shows measurement of efficiency of dc shunt and series motor. Speed control of dc shunt motor with field and armature. The connection diagram for dc shunt machine is shown in the figure below. To know how to estimate and predict efficiency of a d.
Thus the speed of dc motor is given by, eb v i a r a. To obtain the performance characteristics of a dc shunt motor by load test. When a current carrying conductor is placed in a magnetic field, it experiences a force. Dc starter face plate type suitable for above 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. As you know that the construction of any type of dc motor is very similar to a dc generator. A good material for the poles of a pmdc motor should have the apposite of the above. Reduced field strength will cause high armature currents. To discover the characteristic change in speed of a dc series motor as it is loaded. Working principle of dc shunt motor, dc series motor and all other dc motors can be stated as follows.
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. To discover the characteristic change in torque output of a dc shunt motor as it is loaded. In the case of a dc motor, the magnetic field is produced by the field winding. A dc motor must have 100% field strength to produce its maximum torque and to keep the armature amperage within proper limits. In a shunt dc motor, the armature and field windings are connected in parallel. The open circuit test is needed to determine the open circuit characteristic or magnetizing characteristic of a dc machine.
A shuntwound motor has decreasing torque as speed increases. Geethanjali college of engineering and technology department electrical and electronics engineering list of experiments s. My choice is not only a shuntwound motor, but a straightshuntwound motor. Though there are separate branches for the flow of armature current and field current. With the advent of scrbased dc drive controllers, the need for specific motors has diminished. Working principle of dc shunt motor your electrical guide. Parts and principle of operation of a shunt dc motor.
And the armature winding is connected to external supply voltage hence it plays the role of current carrying conductor. Since they are connected in parallel, the armature and field windings are exposed to the same supply voltage. Speed control methods of dc shunt motor my tech info. 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. Especially in the case of a compoundwound, or a stabilizedstraightshuntwound motor, the addition of a series field was an attempt to keep the motor under stable control.
To conduct load test on dc motor with shunt excitation and plot the typical characteristics. This can be proudly known as workhorse of industrial systems. In this paper discussed about load test of dc series and shunt motor. Calculate the induced voltage, the output power, the efficiency and the torque of the motor if the mechanical and the magnetic losses are 900. In this method, a brake is applied to a watercooled pulley mounted on the motor shaft as shown in fig. Title of the experiment page no 7 retardation test on dc shunt motor. One end of the rope is fixed to the floor via a spring balance s and a known mass is suspended at the other.
This paper discusses the speed and torque control of a shunt dc motor through matlab simulink simulations. 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. Test the shunt field continuity by measuring and recording the resistance of the shunt with an ohmmeter. There are 3 main types of dc motor that are available. 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. The shunt winding has a large number of turns so that it has appreciable inductance. The compound motors are used where higher starting torque and fairly. In this post, we will discuss about various speed control methods of dc shunt motor. 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. C is applied to a shunt motor, the large inductive reactance of shunt winding will reduce the field current too much.
Let us now solve some problems on shunt, separately excited and series motors. 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. The purpose of this load test is to test which is used to test the performance. A stab is shaped piece of metal that makes up a certain type of wound rotor. A dc motor, whose field winding is excited by the current produced by itself, is called selfexcited. 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. Consequently, shunt motor will not usually run on a. The dc supply is switched on with minimum resistance in the field circuit and maximum value of r 1 in the armature circuit. 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. To select the motor type, rightclick on the electric motor block, select variantoverride using and then the desired motor. Speed control of dc shunt motor your electrical guide.
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