We came up with relatively simple and inexpensive solution that may be read more. In this article we are going to discuss about brake test on d. 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. Washing machine motor wired in as series motor suicide motor duration. Open circuit and short circuit tests on single phase transformer. Swinburnes test for dc machines in this technique, the dc generator or dc motor is run as a motor at no load. The armature terminals or supply polarity of a separately excited dc motor or shunt dc motor. Therefore, the supply voltage v and the induced voltage e b i. This is an efficient and effective method of braking most ac motors. In the brake test compound motor we are mainly used in long shunt compound.
Now in this article we are going to discuss about retardation test on dc machines. In this test we get total stray losses nothing but combination of. You can do a simple experiment to distinguish between the coast and brake mode. Continue the experiment till full load of the motor is reached. It is often necessary in many applications to stop a running motor rather quickly.
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. To draw the performance characteristics of the given dc shunt motor by. In this method, a brake is applied to a watercooled pulley mounted on the motor shaft as shown in fig. Batch mates should be able to explain the purpose of the experiment. State two ways by which the output polarity of a separatelyexcited dc shunt generator can be. As the constant loss is known the efficiency can be predetermined at any load. Ee 448 laboratory experiment 4 introduction to dc motors 4 assuming shunt connected dc motor, compute back emf, field resistance, armature resistance, field loss, armature loss, power efficiency, starting torque, and noload speed. To draw the performance characteristics of the given dc shunt motor by conducting load test. Generally, this test can be done for the low rated dc machines. In electrical terms, parallel is generally denoted as shunt.
Assuming stator flux to be linear function of field current, determine the constant kk f. Brake test also called as direct loading test of testing the motor. C shunt generator and to determine the critical field resistance and critical speed. The brake is set when power is removed from the operating coil through stored energy from a torque spring that is compressed when the brake is electrically set. Take a brushed dc motor and try to spin the shaft with your fingers, leaving the leads floating. 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.
Continue the experiment till saturation of the field is reached. Tests on 1phase transformer 12 load test on 1phase transformer. For real dependable measurement you might need special equipment such as an adjustable torque load it could be small particle brake coupled with the motor shaft and measuring tool such as dynamometer. The dc shuntwound motor, running on direct current, has its field windings placed in parallel to the armature. Electrical machines for mechatronics laboratory 7 4 speed control of series dc motors unlike with the shunt dc motor, there is only one efficient way to change the speed a series dc motor. Load test on singlephase transformer and three phase transformers. Brake test in one of the most simple way of finding efficiency of any kind of dc machine. The main advantages of the swinburnes test are as follows. Brake test on dc shunt motor electric motor electrical. Direct method of testing of dc machine, also known as brake test if carried out for a dc motor will be discussed in this post.
To conduct load test on dc shunt generator and to draw its external and internal characteristics 2. It is a direct method and consists of applying a brake to a. Electrical machinel dc laboratory manual grietelectrical and. Electrical and electronics engineering lab manual pdf eee. Three very popular devices used to make things move include dc motors, rc servos, and stepper motors. Ee 448 laboratory experiment 4 introduction to dc motors 2 i. Dc motors although ac motors are used in most of the cases, dc motors have many applications and used for multipurpose applications. Regenerative or hopkinsons test on dc machines is useful to determine the efficiency which the power. To obtain the performance characteristics of a dc shunt motor by load test. Riosque y zack special edition hd recommended for you.
Test result of boosted voltage while running motor at 2500 rpm. 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. 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. C of a dc shunt generator and to determine its critical. The open circuit characteristics for a dc generator are determined as follows. Fields test for series motor this test is applicable to two similar series motors. These experiments consolidates the students knowledge of construction,operation and performance of dc. One machine runs normally as a motor and drives generator whose output is wasted in a variable load r fig. So the load test could be performed in two ways ie, by direct loading by indirectly loading in case of direct loading the motor is provide.
Retardation test is also called as running down test. That is the reason behind naming it a dc shunt motor. Once the losses of the machine are known, its efficiency at any desired load can be determined in advance. Smooth braking of a motor can be achieved by electric braking. Dc motor principle a machine that converts dc power into mechanical energy is known as dc motor. In this technique, the dc generator or dc motor is run as a motor at no load. As resistance increased, the value of the field current will reduce. The following readings are obtained when doing a load test on a d. To verify kirchhoffs voltage and current law in a passive resistive network. Determination of critical field resistance and critical speed. In other words, the motor is stopped by the voltage and current action in the circuit rather than the mechanical friction brakes on the rotor.
The armature terminals or supply polarity of a separately excited dc motor or shunt dc motor when running are reversed. In case of dc shunt motors, armature is disconnected from the supply and a. To conduct load test on dc shunt motor and to find efficiency. Scribd is the worlds largest social reading and publishing site. Two common basic methods used for braking a motor are dc injection braking and dynamic braking. In dc machines this test is applicable only throughout the flux is constant at all load dc shunt machine and dc compound machine. One end of the band is fixed to earth via a spring balance s.
Construction and principle of operation of the shunt dc motor. Dynamic braking or rheostatic braking of dc motor in dynamic braking, a braking resistor rb is connected across the armature as soon as the dc motor is disconnected from the supply mains. Determination of characteristics 3 brake test on dc shunt motor. The motor now works as a generator, producing the braking torque. C shunt motor is conducted and its performance curves are drawn. This is the complete theory of brake test on dc shunt motor including laboratory manual. Maintain constant armature voltage through out the experiment. In this test the efficiency of the machine at any load is predetermined. When the losses of dc machine wellknown, then we can find the efficiency of a dc machine in advance at any desired load. The simple brake test described above can be used for small motors only, because in the case of large motors, it. Apparatus range type quantity 1 ammeter 020a mc 1 2 voltmeter 0300v mc 1 3 rheostat 1250. Swinburnes test is the simplest indirect method of testing dc machines. We will look at both in detail, starting with electric braking. What is theory of brake test on dc shunt motor answers.
This is very efficient way to find out stray losses in dc shunt motors. O if these values are plotted, the graph representing the variation of speed with torque developed is obtained. Brake test is also a method of finding efficiency of dc motors. We know that any moving or rotating object acquires kinetic energy.
We can run the machine as a motor or as a generator. One end of the rope is fixed to the floor via a spring balance s and a known mass is suspended at the other. Swinburnes test is the most commonly used and simplest method of testing of shunt and compound wound dc machines which have constant flux. Regenerative braking of bldc motors by daniel torres, applications engineer. The brake band is fixed with the help of wooden blocks gripping the pulley. To determine the efficiency of the given dc shunt motor by conducting load test. That method is to change the terminal voltage of the motor. In the brake test compound motor we are mainly used in long shunt compound motor. In the previous articles we have seen brake test, hopkinsons test which are essential to find out dc machine efficiency. Electrical machines lab report 12 eet2166 mmu studocu.
Same voltage is applied to both shunt winding and armature in this motor. Since they are connected in parallel, the armature and field windings are exposed to the same supply voltage. Spring balance reading 10 kg and 35 kg diameter of the drum 40 cm speed of the motor 950 r. S1 power switch to switch on sw1 speed switch and starter switch for armature sw2 speed switch for field winding r1 to r9 wirewound high power resistors for the starting of the motor sw2 must be on position 0.
Sno name of the experiment date signature 1 magnetization characteristics of dc shunt generator. This video describes the a load test on dc shunt motor with calculation. What is dynamic braking or rheostatic braking of dc motor. Speed control of dc shunt motor with field and armature rheostat control 79 2. Introduction to electrical power and machines eet2166. To predetermine the efficiency of a dc shunt machine when running both as generator and motor. Dc machines can be tested by three different methods namely direct method, indirect method and regenerative method. For the braking operation in dynamic braking, the motor is connected in two ways. Speed control of dc shunt motor with field and armature. Electrical and electronics engineering lab manual pdf. Swinburnes test and speed control of dc shunt motor.
Geethanjali college of engineering and technology department electrical and electronics engineering list of experiments s. The field current lf is obtained from an external independent dc source. Eee lab manual pdf electrical electronics engineering2020. D c shunt motor make conclusion sd control of dc shunt motor dc shunt motor experiment sd control of dc shunt motor. Sep 18, 2019 to determine experimentally the magnetization or open circuit characteristic of a d. In order to carry out this test, we require two identical d. Applied voltage 200 v line current 30 a calculate the output power and the efficiency. Lab report of electrical machines for lab1 characteristics of dc shunt motor, lab 1. In this method, the dc machine generator or motor is run as a motor at noload and losses of the machine are determined. This parallel configuration allows independent path of current for field winding and armature.
The power required to test a large machine is small. Introduction 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. Brake test on dc shunt motor electric motor electrical engineering. Determination of critical field resistance critical speed. Speed control of dc shunt motor by field and armature control. Heat produced due to friction between belt and brake drum is reduced by pouring. Torque and efficiency calculation simple electric motors. Pdf this paper discusses the speed and torque control of a shunt dc motor through matlab simulink simulations. Brake test on dc shunt motor free download as word doc. Thus, this method is an economical and convenient method of testing of dc machines. 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 braking. Two basic methods used for braking a motor dc injection. Circuit diagram load test on dc shunt motor figure. Jan 29, 2017 this video teach you to understand the speed control method of dc shunt motor with practical demonstration.