Objective identify the components of an ac motor and explain their function. In dc machines this test is applicable only throughout the flux is constant at all load dc shunt machine and dc compound machine. What is a dc shunt motor and its advantage and disadvantage. Two basic methods used for braking a motor dc injection and dynamic photo credit. Be sure to measure the current in the motor wiring which carries the dc injection current. One end of the band is fixed to earth via a spring balance s. Other useful dimensions include the location of mounting holes and thread type. The dc shuntwound motor, running on direct current, has its field windings placed in parallel to the armature. Dc motor principle a machine that converts dc power into mechanical energy is known as dc motor. This particular motor is of the permanent magnet type, with wire windings only on the armature. C motor field windings 25092011 by lemau 2 comments d.
To find out how to reverse the direction of rotation of a series dc motor. 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. That is the reason behind naming it a dc shunt motor. Hopkinsons test is another useful method of testing the efficiency of a dc machine. Brake test on dc shunt motor free download as word doc. This parallel configuration allows independent path of current for field winding and armature. Electrical machines i lab manual anurag college of engineering.
For a standard brushed dc motor, it is easiest to do on a separately excited motor, where the field winding has separate. Methods of testing direct, indirect brake test swinburnes test hopkinsons test fields test retardation test applications of dc motors. Load test on singlephase transformer and three phase transformer connections. First, a look at an incredibly simpli ed motor, a square loop in a magnetic eld, as shown in figure 1. Power supply module 120vac, 0120vdc ems 8821 dc metering module 200v, 5a ems 8412.
To perform the brake test on the given dc compound motor and to. In case of dc shunt motors, armature is disconnected from the supply and a rheostat variable resistor is connected across it. The brake test is the one kind of load test on dc shunt motor. Same voltage is applied to both shunt winding and armature in this motor. Brake test on dc compound motor free download as word doc. A dc motor s general specifications usually include weight, shaft length and shaft diameter as well as motor length and diameter. Induction motors have been ruling the industrial world for many decades. In cumulative compound motor the flux produced by both the windings is in the same direction, i. In this motor field winding is placed in series to the armature. Thus, this method is an economical and convenient method of testing of dc machines.
The power required to test a large machine is small. Two basic methods used for braking a motor dc injection. Dec 21, 2017 81 videos play all dc machines complete course includes fundamentals, motors and generators electrical is easy mix play all mix electrical is easy youtube troubleshooting a motor starter. Brake test is used to determine the efficiency of comparatively small motors. The motor casing where two or more electromagnet pole pieces are housed forms the stationary part of the motor, the stator. Load characteristics of dc compound generator with differential and cumulativeconnections. A belt around the air cooled pulley has its end attached to the spring balance s1 and s2. Dc injection brakes only require a small module located with the other motor switchgear andor drivers, mounted in a remote and convenient location, whereas a friction brake must be mounted somewhere on the rotating system. To conduct the no load test on the dc shunt motor and determine its. These terms relate to the type of connection of the field windings with respect to the armature circuit.
Dc motors although ac motors are used in most of the cases, dc motors have many applications and used for multipurpose applications. This polyphase motor operates with a lag rather than at the synchronous speed. The purpose of this experiment is to examine the construction of a dc motor generator, to learn the basic motor wiring connections, and to study the performance characteristics of a shunt and series dc motor. In electrical terms, parallel is generally denoted as shunt. Dc injection braking is a method of braking in which direct current dc is applied to the stationary windings of an ac motor after the ac voltage is removed. Fields test for series motor this test is applicable to two similar series motors. Apr 25, 2018 dc machines can be tested by three different methods namely direct method, indirect method and regenerative method. Construction and principle of operation of the shunt dc motor. Characteristics of dc series motor studyelectrical. C motor is the one of common application for industrial.
The operating principles of direct current dc motors and generators. Assuming the spring balance to be calibrated in kilogram. Atomic structure, energy band diagram, compare silicon and germanium, hole current, intrinsic semiconductor extrinsic semiconductor, compare voltage amplifier power amplifier, compare audio amplifier tuned amplifier, compare transistor scr, compare transistor mosfet, compare holding current latching current. Experiment 7 series dc motor i objectives to determine the torquespeed characteristic curve. Overview the acdc motor theory course was specifically developed for electricians and electronic technicians as well as for the multicraft training needs of process and manufacturing facilities. As the constant loss is known the efficiency can be predetermined at any load. Swinburnes test and speed control of dc shunt motor. The connection diagram of the compound motor is shown below. Characteristics of dc compound motor dc compound motors have both series as well as shunt winding. 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. Large rotors and loads with a high moment of inertia may take a significant amount of time to stop through inherent friction alone.
Module 2 basic dc theory this module describes the basic concepts of direct current dc electrical circuits and discusses the associated terminology. The selfexcited motors are further classified as shunt wound or shunt motor, series wound or series motor and compound wound or compound motor. The open circuit characteristics for a dc generator are determined as follows. Methods of testing direct, indirect brake test swinburnes test hopkinsons test fields test retardation test.
If only the length or diameter are provided, refer to an image, photo or scale drawing to get a sense of the other dimensions based on. Brake test on dc compound motor electric motor electrical. The field current lf is obtained from an external independent dc source. Aug 03, 2018 hopkinsons test is another useful method of testing the efficiency of a dc machine.
Compound wound dc motor or dc compound motor electrical4u. Generally, this test can be done for the low rated dc machines. The dc shunt motor construction is the same as any type of dc motor. In the induction motors used in lift and hoists, you. Series wound dc motor construction, principle, speed and. There are 3 main types of dc motor that are available. Relationship between the noload speed and the armature. In this article we are going to discuss about brake test on d. A dc motor may be thought of as a series of electromagnets, radially spaced around a common shaft. It is a full load test and it requires two identical machines which are coupled to each other. Induced currents flowing in the rotor cause this slip, which draws high current at its start. Introduction a series dc motor is a motor whose filed windings consists of a relatively few turns connected in. Introduction a series dc motor is a motor whose filed windings consists of a relatively few turns connected in series with the armature circuit. Save 1 1 5a circuit theory hand calculations for later.
How do i interpret dc motor specifi robotshop community. The interaction of the generated magnetic field and external magnetic field results in the rotational movement. One end of the rope is fixed to the floor via a spring balance s and a known mass is suspended at the other. A compound wound dc motor also known as a dc compound motor is a type of selfexcited motor, and is made up of both series the field. Instructions for the installation, operation and maintenance of elektrim three phase induction brake motors 143t286t frame per nema standards type sgm tefc ip55 a24011. The most common ac motor is the highly versatile threephase induction motor. 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.
It is a direct method and consists of applying a brake to a. This course consists of 11 interactive, online lessons that address ac and dc motor theory. 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. 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. A compound wound motor has both a series and a shunt field winding, i. Installation manual for dc injection brake units pds 1100a page 4 of 17 issue 15 3. Load characteristics of dc shunt and compound motor. The different types of dc motors and generators and their particularities. Jun 02, 2015 brake test it is a direct method and consists of applying a brake to a watercooled pulley mounted on the motor shaft as shown in fig.
Using belt tightening hand wheels h1 and h2, the load of motor is adjusted to its rated value. The main advantages of the swinburnes test are as follows. Brake test on dc shunt motor electric motor electrical engineering. For a permanent magnet dc motor just reverse the polarity of the supply voltage. When power is disconnected from the motor, the rotor spins freely until friction slows it to a stop. Series motors which are mainly used for traction work are easily available in pairs. Dc series motor works on the direct current converting electrical energy to mechanical energy. Connect the brake supply cable inserted into the motor terminal box according to the diagram on the inside of the box cover, while connecting the brake with the motor maintain all the necessary. Direct method of testing of dc machine, also known as brake test. When the losses of dc machine wellknown, then we can find the efficiency of a dc machine in advance at any desired load. 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. 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. To reduce downtime, or possibly as an emergency safety feature, dc injection braking can be used to quickly stop the rotor.
In case of dc shunt motors, armature is disconnected from the supply and a. A dc series motor is one type of dc motor in which field winding is connected in series with the armature winding. Types of dc motor a direct current motor, dc is named according to the connection of the field winding with the armature. Electrical machinel dc laboratory manual grietelectrical and. Construction and principle of operation of dc series motor. The minimum equipment required is a dc clipon ammeter. For conducting brake test on dc series motor, it must be ensured that belt is sufficiently tight before the motor is switched on to the sully as dc. Brake test is also a method of finding efficiency of dc motors. The motor is loaded directly by means of a mechanical brake load or by means of an eddy current or a calibrated air fan. The final stage of brake installation onto the motor is mounting the fan and inserting the brake supply cable into the motor terminal box, 8. A dc motor having both shunt and series field windings is called a compound motor. Brake test also called as direct loading test of testing the motor. One machine runs normally as a motor and drives generator whose output is wasted in a variable load r fig. The compound motor is further subdivided as cumulative compound motor and differential compound motor.
The performance of any motor can be judged from its characteristic curves known as motor characteristics. Brake test of dc motor is carried out as shown in figure below. Because loading will be applied directly on shaft of the motor by means of a belt and pulley arrangement. A dc motors general specifications usually include weight, shaft length and shaft diameter as well as motor length and diameter. To obtain the performance characteristics of a dc shunt motor by load test. It works on the principle of generation of rotational motion when a conductor placed in magnetic field carries current. Volume 2 of 4 module 3 dc circuits this module introduces the rules associated with the reactive components of inductance and capacitance and how they affect dc circuits. The brake band is fixed with the help of wooden blocks gripping the pulley. Series wound dc motor as we said before that this type of dc motor is a selfexcited dc motor which converts electrical power into mechanical power based on electromechanical law, but in this motor, the field winding is connected in series to the armature winding. In this technique, the dc generator or dc motor is run as a motor at no load. A compoundwound motor has both a series and a shunt field winding, i. The electric braking of a dc motor is of three types, i rheostatic or dynamic braking, ii plugging or reverse current braking and iii regenerative beaking. Dc machines can be tested by three different methods namely direct method, indirect method and regenerative method.
Its operation is based on the principle that when a current carrying conductor is placed in a. One of these two machines is operated as a generator to supply the mechanical power to the motor. A dc injection brake system can be used as an alternative to a friction brake system. First, one is separately excited dc motor and selfexcited dc motor.
What is theory of brake test on dc shunt motor answers. Fields test for series motor this test is applicable to two similar series. In this method, a brake is applied to a watercooled pulley mounted on the motor shaft as shown in fig. The electrical layout of a typical series wound dc motor is shown in the diagram. Download as docx, pdf, txt or read online from scribd. In this post, we will look into the characteristics of a dc series motor. A dc series motor has all the 6 fundamental componentsaxle, rotor armature, stator, commutator, field magnets and brushesthat are present in a generic dc motor. Scribd is the worlds largest social reading and publishing site. Write the necessary magnetic polarities n for north and s for south on the armatures electromagnet pole tips, in order to. Load test on singlephase transformer and three phase. The purpose of this experiment is to examine the construction of a dc motorgenerator, to learn the basic motor wiring connections, and to study the performance characteristics of a shunt and series dc motor.