The document discusses various topics related to DC machines including Maxwell's corkscrew rule, Fleming's left-hand and right-hand rules, Lenz's law, the construction and working principles of DC generators and motors. It describes the field system, armature, commutator, brushes, and winding types in DC machines. It also covers EMF equations, characteristics, speed control methods, losses, testing, and applications of DC generators and motors.
It the ppt on Dc machines. Dc machines is. A very good ppt. You can learn more about dc machines. Dc machines are important for science dc are machines are also important for science The DC machine can be classified into two types namely DC motors as well as DC generators. Most of the DC machines are equivalent to AC machines because they include AC currents as well as AC voltages in them. The output of the DC machine is DC output because they convert AC voltage to DC voltage. The conversion of this mechanism is known as the commutator, thus these machines are also named as commutating machines. DC machine is most frequently used for a motor. The main benefits of this machine include torque regulation as well as easy speed. The applications of the DC machine is limited to trains, mills, and mines. For example, underground subway cars, as well as trolleys, may utilize DC motors. In the past, automobiles were designed with DC dynamos for charging their batteries.
What is a DC Machine?
A DC machine is an electromechanical energy alteration device. The working principle of a DC machine is when electric current flows through a coil within a magnetic field, and then the magnetic force generates a torque that rotates the dc motor. The DC machines are classified into two types such as DC generator as well as DC motor.
DC Machine
DC Machine
The main function of the DC generator is to convert mechanical power to DC electrical power, whereas a DC motor converts DC power to mechanical power. The AC motor is frequently used in industrial applications for altering electrical energy to mechanical energy. However, a DC motor is applicable where good speed regulation & an ample range of speeds are necessary like in electric-transaction systems.
Construction of DC Machine
The construction of the DC machine can be done using some of the essential parts like Yoke, Pole core & pole shoes, Pole coil & field coil, Armature core, Armature winding otherwise conductor, commutator, brushes & bearings. Some of the parts of the DC machine is discussed below.
Construction of DC Machine
Construction of DC Machine
Yoke
Another name of a yoke is the frame. The main function of the yoke in the machine is to offer mechanical support intended for poles and protects the entire machine from moisture, dust, etc. The materials used in the yoke are designed with cast iron, cast steel otherwise rolled steel.
Pole and Pole Core
The pole of the DC machine is an electromagnet and the field winding is winding among pole. Whenever field winding is energized then the pole gives magnetic flux. The materials used for this are cast steel, cast iron otherwise pole core. It can be built with the annealed steel laminations for reducing the power drop because of the eddy currents.
PCBWay
Pole Shoe
Pole shoe in the DC machine is an extensive part as well as to enlarge the region of the pole. Because of this region, flux can be spread out within the air-gap as well as extra flux can be passed
It the ppt on Dc machines. Dc machines is. A very good ppt. You can learn more about dc machines. Dc machines are important for science dc are machines are also important for science The DC machine can be classified into two types namely DC motors as well as DC generators. Most of the DC machines are equivalent to AC machines because they include AC currents as well as AC voltages in them. The output of the DC machine is DC output because they convert AC voltage to DC voltage. The conversion of this mechanism is known as the commutator, thus these machines are also named as commutating machines. DC machine is most frequently used for a motor. The main benefits of this machine include torque regulation as well as easy speed. The applications of the DC machine is limited to trains, mills, and mines. For example, underground subway cars, as well as trolleys, may utilize DC motors. In the past, automobiles were designed with DC dynamos for charging their batteries.
What is a DC Machine?
A DC machine is an electromechanical energy alteration device. The working principle of a DC machine is when electric current flows through a coil within a magnetic field, and then the magnetic force generates a torque that rotates the dc motor. The DC machines are classified into two types such as DC generator as well as DC motor.
DC Machine
DC Machine
The main function of the DC generator is to convert mechanical power to DC electrical power, whereas a DC motor converts DC power to mechanical power. The AC motor is frequently used in industrial applications for altering electrical energy to mechanical energy. However, a DC motor is applicable where good speed regulation & an ample range of speeds are necessary like in electric-transaction systems.
Construction of DC Machine
The construction of the DC machine can be done using some of the essential parts like Yoke, Pole core & pole shoes, Pole coil & field coil, Armature core, Armature winding otherwise conductor, commutator, brushes & bearings. Some of the parts of the DC machine is discussed below.
Construction of DC Machine
Construction of DC Machine
Yoke
Another name of a yoke is the frame. The main function of the yoke in the machine is to offer mechanical support intended for poles and protects the entire machine from moisture, dust, etc. The materials used in the yoke are designed with cast iron, cast steel otherwise rolled steel.
Pole and Pole Core
The pole of the DC machine is an electromagnet and the field winding is winding among pole. Whenever field winding is energized then the pole gives magnetic flux. The materials used for this are cast steel, cast iron otherwise pole core. It can be built with the annealed steel laminations for reducing the power drop because of the eddy currents.
PCBWay
Pole Shoe
Pole shoe in the DC machine is an extensive part as well as to enlarge the region of the pole. Because of this region, flux can be spread out within the air-gap as well as extra flux can be passed
This presentation is about the whole pricipal about DC machine. It explain the various important parts of dc machine.It tells about how many types of losses are present in DC machine.
This presentation is about the whole pricipal about DC machine. It explain the various important parts of dc machine.It tells about how many types of losses are present in DC machine.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
3. Maxwell’s Cork screw Rule :
Hold the cork screw in yr right
hand and rotate it in clockwise
in such a way that it advances in
the direction of current. Then
the direction in which the hand
rotates will be the direction of
magnetic lines of force .
5. Fleming’s left hand rule
Used to determine the direction of force acting
on a current carrying conductor placed in a
magnetic field .
The middle finger , the fore finger and thumb of
the left hand are kept at right angles to one
another .
The middle finger represent the direction
of current
The fore finger represent the direction of
magnetic field
The thumb will indicate the direction of
force acting on the conductor .
This rule is used in motors.
7. Fleming’s Right hand rule
Used to determine the direction of emf induced
in a conductor
The middle finger , the fore finger and thumb of
the left hand are kept at right angles to one
another.
The fore finger represent the direction
of magnetic field
The thumb represent the direction of
motion of the conductor
The middle finger will indicate the
direction of the inducted emf .
This rule is used in DC Generators
8. Len’s Law
The direction of induced emf is given by
Lenz’s law .
According to this law, the induced emf will
be acting in such a way so as to oppose the
very cause of production of it .
e = -N (dØ/dt) volts
9. DC Generator
Mechanical energy is converted to electric
energy
Three requirements are essential
1. Conductors
2. Magnetic field
3. Mechanical energy
10. Working principle
A generator works on the principles of
Faraday’s law of electromagnetic induction
Whenever a conductor is moved in the
magnetic field , an emf is induced and the
magnitude of the induced emf is directly
proportional to the rate of change of flux
linkage.
This emf causes a current flow if the
conductor circuit is closed .
19. Armature winding
There are 2 types of winding
Lap and Wave winding
Lap winding
A = P
The armature
windings are
divided into
no. of sections
equal to the no
of poles
Wave winding
A = 2
It is used in low
current output
and high voltage.
2 brushes
20. Field system
It is for uniform magnetic field within
which the armature rotates.
Electromagnets are preferred in
comparison with permanent magnets
They are cheap , smaller in size ,
produce greater magnetic effect and
Field strength can be varied
22. Armature core
The armature core is cylindrical
High permeability silicon steel
stampings
Impregnated
Lamination is to reduce the eddy
current loss
23. Commutator
Connect with external circuit
Converts ac into unidirectional current
Cylindrical in shape
Made of wedge shaped copper segments
Segments are insulated from each other
Each commutator segment is connected to
armature conductors by means of a cu strip called
riser.
No of segments equal to no of coils
24. Carbon brush
Carbon brushes are used in DC machines
because they are soft materials
It does not generate spikes when they contact
commutator
To deliver the current thro armature
Carbon is used for brushes because it has
negative temperature coefficient of resistance
Self lubricating , takes its shape , improving
area of contact
26. Carbon brush
Brush leads (pig tails)
Brush rocker ( brush gear )
Front end cover
Rear end cover
Cooling fan
Bearing
Terminal box
27. EMF equation
Let,
Ø= flux per pole in weber
Z = Total number of conductor
P = Number of poles
A = Number of parallel paths
N =armature speed in rpm
Eg = emf generated in any on of the
parallel path
28. EMF equation
Flux cut by 1 conductor
in 1 revolution = P * φ
Flux cut by 1 conductor in
60 sec = P φ N /60
Avg emf generated in 1
conductor = PφN/60
Number of conductors in
each parallel path = Z /A
Eg = PφNZ/60A
29. DC generators are generally classified
according to their method of excitation .
Separately excited DC generator
Self excited D C generator
Types of DC Generator
30. Further classification of DC Generator
Series wound generator
Shunt wound generator
Compound wound generator
Short shunt & Long shunt
Cumulatively compound
&
Differentially compound
31. No load saturation characteristic (Eo/If)
Internal or Total characteristic (E/ Ia)
External characteristic (V/I)
Characteristics
32. For appreciable generation of emf, the
field resistance must be always less
certain resistance, that resistance is
called as the critical resistance of the
machine .
Critical field resistance
33. Magnetic neutral axis :
It is perpendicular to the lines of force
between the two opposite adjacent poles.
Leading pole Tip (LPT) :
It is the end of the pole which first
comes in contact with the armature.
Trailing pole tip :
It is the end of the pole which comes in
contact later with the armature.
General terms used in Armature
reaction
35. Effects of Armature Reaction
It decreases the efficiency of the machine
It produces sparking at the brushes
It produces a demagnetising effect on the
main poles
It reduces the emf induced
Self excited generators some times fail to
build up emf
36. Armature reaction remedies
1.Brushes must be shifted to the new position of
the MNA
2.Extra turns in the field winding
3.Slots are made on the tips to increase the
reluctance
4. The laminated cores of the shoe are staggered
5. In big machines the compensating winding at
pole shoes produces a flux which just opposes
the armature mmf flux automatically.
37. Commutation
The change in direction of current takes
place when the conductors are along the
brush axis .
During this reverse process brushes short
circuit that coil and undergone
commutation
Due to this sparking is produced and the
brushes will be damaged and also causes
voltage dropping.
38. Losses in DC Generators
1. Copper losses or variable losses
2. Stray losses or constant losses
Stray losses : consist of (a) iron losses or core
losses and (b) windage and friction losses .
Iron losses : occurs in the core of the machine
due to change of magnetic flux in the core .
Consist of hysteresis loss and eddy current
loss.
Hysteresis loss depends upon the frequency ,
Flux density , volume and type of the core .
39. Losses
Hysteresis loss depends upon the frequency ,
Flux density , volume and type of the core .
Eddy current losses : directly proportional to
the flux density , frequency , thickness of the
lamination .
Windage and friction losses are constant due to
the opposition of wind and friction .
40. Shunt Generators:
a. in electro plating
b. for battery recharging
c. as exciters for AC generators.
Applications
Series Generators :
A. As boosters
B. As lighting arc lamps
41. DC Motors
Converts Electrical energy into Mechanical
energy
Construction : Same for Generator and
motor
Working principle : Whenever a current
carrying conductor is placed in the
magnetic field , a force is set up on the
conductor.
42. Back emf
The induced emf in the rotating armature
conductors always acts in the opposite
direction of the supply voltage .
According to the Lenz’s law, the direction of the
induced emf is always so as to oppose the
cause producing it .
In a DC motor , the supply voltage is the cause
and hence this induced emf opposes the
supply voltage.
43. Classification of DC motors
DC motors are mainly classified into
three types as listed below:
Shunt motor
Series motor
Compound motor
Differential compound
Cumulative compound
44. Torque
The turning or twisting force about an
axis is called torque .
P = T * 2 πN/ 60
Eb Ia = Ta * 2 πN/ 60
T ∞ φ I a
Ta ∞ I2a
45. Characteristic of DC motors
T/ Ia characteristic
N/ I a characteristic
N/T characteristic
46. According to the speed equation of a dc motor
N ∞ Eb/φ
∞ V- Ia Ra/ φ
Thus speed can be controlled by-
Flux control method: By Changing the flux by
controlling the current through the field
winding.
Armature control method: By Changing the
armature resistance which in turn changes
the voltage applied across the armature
Speed control of DC motors
47. 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 .
Hence this method is economical
Disadvantages:
Flux can be increased only upto its rated value
High speed affects the commutation, motor operation
becomes unstable
Flux control
48. Armature voltage control method
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 .
49. Starters for DC motors
Needed to limit the starting current .
1. Two point starter
2. Three point starter
3. Four point starter
50. 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.
Indirect method: Swinburne’s test is an indirect method of
testing DC shunt machines to predetermine the effficency
, as a motor and as a Generator. In this method, efficiency
is calculated by determining the losses .
Testing of DC machines