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Dc machine ppt free download.Chapter 3. DC Machines
DC Motors. Construction very similar to a DC generator The dc machine can operate bath as a generator and a motor. When the dc machine operates as a motor, the input to the machine is electrical power and the output is mechanical power. In fact, the dc machine is used more as dc machine ppt free download motor.
Gas turbine, diesel engine, electrical motor. Adjustable speed, medium starting torque. Applications: centrifugal pump, machine tools, blowers fans, reciprocating dc machine ppt free download, etc. Series Motors: Variable speed motor which dc machine ppt free download speed drastically from one load condition to как сообщается здесь. It has a high starting torque.
Applications: hoists, electric trains, conveyors, elevators, electric cars. Compound motors: Variable speed motors. It has a high starting torque and the no-load speed is controllable unlike in series motors. Applications: Rolling mills, sudden temporary loads, heavy machine tools, punches, etc. Example 11 Q. At no-load condition, the motor runs at rpm and the armature current takes 6 A.
The magnetization dc machine ppt free download at rpm is shown in the next figure. Example Good speed regulation. Maintain maximum torque capability. Expensive control. Unable to maintain maximum torque capability. Simple and cheap control. Poor speed regulation. High Losses. Unable to maintain maximum torque capability TL rated. The drive speed is varied from 0 to rpm base speed by varying the dc machine ppt free download voltage from 0 to V with the field current maintained constant.
Series Motor. The torque required by the fan is proportional to the square of the speed. Neglect armature reaction and rotational loss. Determine the value of this resistance and the power delivered to the fan.
As speed dc machine ppt free download Rae can be gradually taken out without the current exceed a limit starter box. Initially at position 1, as the speed increases, the starter move to position 2,3,4and 5, Development of a DC motor starter.
When operated at no-load from a DC source of 50 V, its operates здесь rpm and draw a current of 1. Find: i. The torque constant, Km ii. The no-load rotational losses iii. The armature current and the motor power output when it is operating at rpm from a 48 V source Fgrt; pg 0. The system uses the motor-generator set M-G set control the speed of a DC motor. Normally AC motor runs at constant speed is used as prime mover.
The generator field current Ifg is changed such that Vt changes from zero to its rated. In this mode, the armature voltage Vt remains constant and the motor field current Ifm is decreased to obtain higher speeds.
Low ripple, fast response. Controlled Rectifier 1-phase or 3-phase Основываясь на этих данных phase rectifier Three phase rectifier.
Chopper Control. Load torque increases, speed decreases, speed error eN increases, results in control signal Vc increases — decrease in the converter firing angle controlled rectifeiror increases in duty cycle chopper to restore back the speed. Chopper or Control rectifier Voltage control Speed demand Closed loop speed control system basic system. The rated current is 40 A. The AC supply voltage is V. Assume the motor current is constant and ripple free.
Sketch the torque speed profile for this type of motor. The armature resistance and field resistance are 0. In order to control the speed, an additional resistance is added in series in the armature circuit. The flux remains constant in the machine. Create Presentation Download Presentation. Skip this Video. Loading SlideShow in 5 Seconds. Download Presentation. Share Presentations. Email Presentation to Friend. Uploaded on Jan 07, Download Presentation DC Motors.
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❿Presentation on theme: "Introduction to DC Machine"— Presentation transcript: - Dc machine ppt free download
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Export and Deals around the world At very affordable rates. Advantages of flux control: It provides relatively smooth and easy control Speed control above rated speed is possible As the field winding resistance is high the field current is small.
Power loss in the external resistance is small. Armature voltage control The speed is directly proportional to the voltage applied across the armature. Voltage across armature can be controlled by adding a variable resistance in series with the armature Potential divider control : If the speed control from zero to the rated speed is required , by rheostatic method then the voltage across the armature can be varied by connecting rheostat in a potential divider arrangement.
Starters for DC motors Needed to limit the starting current. Two point starter 2. Three point starter 3. To determine the efficiency of as DC motor , the output and input should be known. There are two methods. The load test or The direct method The indirect method Direct method: In this method , the efficiency is determined by knowing the input and output power of the motor.
In this method, efficiency is calculated by determining the losses. You just clipped your first slide! Clipping is a handy way to collect important slides you want to go back to later. Now customize the name of a clipboard to store your clips. Visibility Others can see my Clipboard. Cancel Save. Get SlideShare without ads Enjoy access to millions of presentations, documents, ebooks, audiobooks, magazines, and more ad-free. Read free for 60 days.
ShashidharPatil16 Feb. SrijanSen5 Jan. DC motor stator with poles. Rotor of a dc motor. Details of the commutator of a dc motor. A four pole dc machine has an armature of radius 15 cm and an effective length of 30 cm. The armature winding consists of 35 coils, each coil having seven turns.
The coils are accommodated in 35 slots. The average flux density under each pole is 0. Example 2 If the dc machine armature in example 1 is wave-wound, repeat parts a - d. This leads to the load commutation process. The commutation process will takes place with sparking flash over the so called rotational fire. So the armature reaction strengthens the main field flux at one pole and weakness on the other pole end.
Methods of minimizing armature reaction effects Generally there are four possible types of methods. High reluctance pole tips The reluctance pole tips can be increased by increasing the length of the air gap which can be accomplished by using the so called chambered pole tips. During the design of the machine It could be seen in the design stage that the field mmf is sufficiently stronger than in comparison with the armature mmf at full load condition.
Inter poles The effect of armature reaction in the inter polar zone commutating zone can be minimized by using inter poles which are placed exactly mid way between the main poles. Inter poles are narrow poles not to affect the main field flux. In order to achieve automatic regulation of the armature reaction in the inter polar zone, the inter pole winding must be connecting in series with the armature winding.
Compensating winding The inter pole winding mmf is effective only in the commutating zone in other words the A. R effect in the inter polar zone over come. This means the flux will be weakening still there. To overcome this problem compensating winding is applied located in the slots in the pole faces. To achieve automatic regulation with loading condition, the compensating winding also connected in series with armature winding.
R effect in the inter polar zone improves the commutation process. Commutation When conductors come under the influence of south pole, from the influence of north pole the direction of current flow in them is reversed.
This reversal of current in a coil will take place when the two comutater segment to which the coil is connected are being short circuited by brush. The process of reversal current in a coil is known as commutation. The main cause of sparking in DC machine is the self induced emf in the coli which under goes in the process of current reversal. Resistance Commutation:- Replacing low resistance copper brush comparatively high resistance carbon brush's 2.
Emf commutation reversing emf :-most effective by inter poles. Dc Motor Characteristics The three Important characteristic curves of dc motors are: 1.
Torque-Armature Current Characteristic:- This characteristic curve gives relation between mechanical torque T and armature current Ia. This is known as electrical characteristic. Speed-Armature Current Characteristic:- This characteristic curve gives relation between speed N and armature current Ia 3.
Speed-Torque Characteristic:- This characteristic curve gives relation between speed N and mechanical torque T. This is also known as mechanical characteristics. Characteristics of Dc Series Motors a. Magnetic characteristic In case of dc series motors the flux varies with the variation in line or armature current as the field is in series with the armature. The flux increase following a linear law with the increase in load current, becomes maximum at saturation point and finally become constant.
What additional resistance must be inserted in the field circuit to reduce the load voltage to V. When the dc machine operates as a motor, the input to the machine is electrical power and the output is mechanical power. In fact, the dc machine is used more as a motor.
DC motors can provide a wide range of accurate speed and torque control. Principle of operation — when a current-carrying conductor is placed in magnetic field, it experiences a mechanical force.
Gas turbine, diesel engine, electrical motor. Shunt Motors Field and armature windings are connected in parallel. Adjustable speed, medium starting torque. Applications: centrifugal pump, machine tools, blowers fans, reciprocating pumps, etc. Series Motors: Variable speed motor which changes speed drastically from one load condition to another. It has a high starting torque. Applications: hoists, electric trains, conveyors, elevators, electric cars.
Compound motors: Variable speed motors. It has a high starting torque and the no-load speed is controllable unlike in series motors. Applications: Rolling mills, sudden temporary loads, heavy machine tools, punches, etc. At no-load condition, the motor runs at rpm and the armature current takes 6 A. Find the value of shunt field control Rfc Find the rotational losses at rpm Find the speed, torque, and efficiency when the rated current flows.
Example Good speed regulation. Maintain maximum torque capability. Expensive control. Unable to maintain maximum torque capability. Simple and cheap control. Poor speed regulation. High Losses. Unable to maintain maximum torque capability TL rated. The drive speed is varied from 0 to rpm base speed by varying the terminal voltage from 0 to V with the field current maintained constant. Neglect all losses. The torque required by the fan is proportional to the square of the speed.
Neglect armature reaction and rotational loss. Determine the value of this resistance and the power delivered to the fan. Ia can be limited to a safe value by: Insert an external resistance, Rae Use a low dc voltage Vt at starts, which require a variable-voltage supply With external resistance,. As speed increases Rae can be gradually taken out without the current exceed a limit starter box.
Initially at position 1, as the speed increases, the starter move to position 2,3,4and 5, Development of a DC motor starter. Determine the starting current if no starting resistance is used in the armature circuit Determine the value of the starting resistance if the starting current is limited to twice the rated current This dc machine is to run as a motor, using starter box. When operated at no-load from a DC source of 50 V, its operates at rpm and draw a current of 1.
Find: i. The torque constant, Km ii.
❿Dc machine ppt free download
The average flux density under each pole is 0. Example 2 If the dc machine armature in example 1 is wave-wound, repeat parts a - d. Represents the saturation level in the magnetic system of the dc machine for various values of the excitation mmf.
Voltage Ea Field current, if. There are 72 coils on the armature, each containing 12 turns. The flux per pole in the machine is 0. Determine the induced voltage Ea. The resistance of each turn is 0. Ajay Bambhaniya Jul. Total views. Unlimited Reading Learn faster and smarter from top experts. Unlimited Downloading Download to take your learnings offline and on the go. Read and listen offline with any device. Free access to premium services like Tuneln, Mubi and more.
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Thank you! In a traditional electric motor, the rotor rotating part spins inside the stator static part ; in a linear motor, the stator is unwrapped and laid out flat and the "rotor" moves past it in a straight line. Linear motors often use superconducting magnets, which are cooled to low temperatures to reduce power consumption PowerPoint PPT presentation free to view. It is an effective speed control method. Motor - Motor Mechanical Energy Motor Rewinding in chennai Power Plant Motor in Chennai - yuvaraj electrical We are very proud to be as a service contractor for Motors.
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Brushless DC motors offer advantages such as lower rotor heat, higher efficiency, low maintenance costs, operating speed and peak point performance, and rapid response, making it ideal for a wide range of applications, particularly in electric and hybrid vehicles.
Electric motors are used to transfer electrical energy to mechanical energy, most commonly by the use of electromagnetic phenomena. Electric motors of different sorts, including as AC motors, DC motors, Hermetic motors, synchronous ac motor and others, are widely used. Induction Motor Protection System - This Ppt exlains how protect an induction motor from single phasing and over temperature. It also provides a protection system is very important in industries, using lot of motors such that production is not hampered owing to failure of any motor.
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The generator field current Ifg is changed such that Vt changes from zero to its rated. In this mode, the armature voltage Vt remains constant and the motor field current Ifm is decreased to obtain higher speeds.
Low ripple, fast response. Controlled Rectifier 1-phase or 3-phase Single phase rectifier Three phase rectifier. Chopper Control. Load torque increases, speed decreases, speed error eN increases, results in control signal Vc increases — decrease in the converter firing angle controlled rectifeir , or increases in duty cycle chopper to restore back the speed.
Chopper or Control rectifier Voltage control Speed demand Closed loop speed control system basic system. The rated current is 40 A. The AC supply voltage is V. Assume the motor current is constant and ripple free. Sketch the torque speed profile for this type of motor. Chanisorn Limsutjakul. Box4life naba. Masud Rana.
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SOLAR tracker. Electrical Machines I. Chapter 2 DC Machines. Lecture Note.
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