The document provides information on the construction and operation of a three phase induction motor. It discusses the main components of the stator and rotor. The stator contains windings and is made of laminated steel, while the rotor can be either a squirrel cage or wound type. When the stator is energized with AC voltage, it produces a rotating magnetic field that induces currents in the rotor. The interaction between these currents and the stator field produces torque that causes the rotor to rotate. The document also examines various design considerations for the motor such as the choice of specific magnetic and electric loadings, dimensions, winding configuration and core construction.
Output equation of Induction motor; Main dimensions; Separation of D and L; Choice of Average flux density; length of air gap; Design of Stator core; Rules for selecting rotor slots of squirrel cage machines; Design of rotor bars and slots; Design of end rings; Design of wound rotor; Magnetic leakage calculations; Leakage reactance of polyphase machines; Magnetizing current; Short circuit current; Operating characteristics; Losses and Efficiency.
An alternator is an electrical generator that converts mechanical energy to electrical energy in the form of alternating current. For reasons of cost and simplicity, most alternators use a rotating magnetic field with a stationary armature.
Output equation of Induction motor; Main dimensions; Separation of D and L; Choice of Average flux density; length of air gap; Design of Stator core; Rules for selecting rotor slots of squirrel cage machines; Design of rotor bars and slots; Design of end rings; Design of wound rotor; Magnetic leakage calculations; Leakage reactance of polyphase machines; Magnetizing current; Short circuit current; Operating characteristics; Losses and Efficiency.
An alternator is an electrical generator that converts mechanical energy to electrical energy in the form of alternating current. For reasons of cost and simplicity, most alternators use a rotating magnetic field with a stationary armature.
Code of Practice for Power Installations, materials required for power circuit wiring and
their specifications, Prepare the layout diagram of machines showing clearances as per IS
standards, draw wiring plan of the Power circuit for workshops, Decide the type of wiring system, load calculations, determine the size of conductors, main switch, Isolators, sub
switches and protective devices, Draw the SLD of Power Distribution Scheme showing
grading/discrimination of ratings of protective devices, Prepare the schedule of materials with
specifications for workshops and their estimates, Determine the rating of motor for IP set and
the concept (only)of pump house wiring.
Output equations; Main Dimensions; kVA output for 1 & 3 phase transformers; Window space factor; Design of core and winding; Overall dimensions; Operating characteristics; No-load current; Temperature rise in Transformers; Design of Tank; Methods of cooling of Transformers.
About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Code of Practice for Power Installations, materials required for power circuit wiring and
their specifications, Prepare the layout diagram of machines showing clearances as per IS
standards, draw wiring plan of the Power circuit for workshops, Decide the type of wiring system, load calculations, determine the size of conductors, main switch, Isolators, sub
switches and protective devices, Draw the SLD of Power Distribution Scheme showing
grading/discrimination of ratings of protective devices, Prepare the schedule of materials with
specifications for workshops and their estimates, Determine the rating of motor for IP set and
the concept (only)of pump house wiring.
Output equations; Main Dimensions; kVA output for 1 & 3 phase transformers; Window space factor; Design of core and winding; Overall dimensions; Operating characteristics; No-load current; Temperature rise in Transformers; Design of Tank; Methods of cooling of Transformers.
About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
COLLEGE BUS MANAGEMENT SYSTEM PROJECT REPORT.pdfKamal Acharya
The College Bus Management system is completely developed by Visual Basic .NET Version. The application is connect with most secured database language MS SQL Server. The application is develop by using best combination of front-end and back-end languages. The application is totally design like flat user interface. This flat user interface is more attractive user interface in 2017. The application is gives more important to the system functionality. The application is to manage the student’s details, driver’s details, bus details, bus route details, bus fees details and more. The application has only one unit for admin. The admin can manage the entire application. The admin can login into the application by using username and password of the admin. The application is develop for big and small colleges. It is more user friendly for non-computer person. Even they can easily learn how to manage the application within hours. The application is more secure by the admin. The system will give an effective output for the VB.Net and SQL Server given as input to the system. The compiled java program given as input to the system, after scanning the program will generate different reports. The application generates the report for users. The admin can view and download the report of the data. The application deliver the excel format reports. Because, excel formatted reports is very easy to understand the income and expense of the college bus. This application is mainly develop for windows operating system users. In 2017, 73% of people enterprises are using windows operating system. So the application will easily install for all the windows operating system users. The application-developed size is very low. The application consumes very low space in disk. Therefore, the user can allocate very minimum local disk space for this application.
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.
Quality defects in TMT Bars, Possible causes and Potential Solutions.PrashantGoswami42
Maintaining high-quality standards in the production of TMT bars is crucial for ensuring structural integrity in construction. Addressing common defects through careful monitoring, standardized processes, and advanced technology can significantly improve the quality of TMT bars. Continuous training and adherence to quality control measures will also play a pivotal role in minimizing these defects.
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.
Forklift Classes Overview by Intella PartsIntella Parts
Discover the different forklift classes and their specific applications. Learn how to choose the right forklift for your needs to ensure safety, efficiency, and compliance in your operations.
For more technical information, visit our website https://intellaparts.com
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
Automobile Management System Project Report.pdfKamal Acharya
The proposed project is developed to manage the automobile in the automobile dealer company. The main module in this project is login, automobile management, customer management, sales, complaints and reports. The first module is the login. The automobile showroom owner should login to the project for usage. The username and password are verified and if it is correct, next form opens. If the username and password are not correct, it shows the error message.
When a customer search for a automobile, if the automobile is available, they will be taken to a page that shows the details of the automobile including automobile name, automobile ID, quantity, price etc. “Automobile Management System” is useful for maintaining automobiles, customers effectively and hence helps for establishing good relation between customer and automobile organization. It contains various customized modules for effectively maintaining automobiles and stock information accurately and safely.
When the automobile is sold to the customer, stock will be reduced automatically. When a new purchase is made, stock will be increased automatically. While selecting automobiles for sale, the proposed software will automatically check for total number of available stock of that particular item, if the total stock of that particular item is less than 5, software will notify the user to purchase the particular item.
Also when the user tries to sale items which are not in stock, the system will prompt the user that the stock is not enough. Customers of this system can search for a automobile; can purchase a automobile easily by selecting fast. On the other hand the stock of automobiles can be maintained perfectly by the automobile shop manager overcoming the drawbacks of existing system.
Event Management System Vb Net Project Report.pdfKamal Acharya
In present era, the scopes of information technology growing with a very fast .We do not see any are untouched from this industry. The scope of information technology has become wider includes: Business and industry. Household Business, Communication, Education, Entertainment, Science, Medicine, Engineering, Distance Learning, Weather Forecasting. Carrier Searching and so on.
My project named “Event Management System” is software that store and maintained all events coordinated in college. It also helpful to print related reports. My project will help to record the events coordinated by faculties with their Name, Event subject, date & details in an efficient & effective ways.
In my system we have to make a system by which a user can record all events coordinated by a particular faculty. In our proposed system some more featured are added which differs it from the existing system such as security.
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.
2. Introduction
A poly phase induction motor consists of two major parts,
the stator and rotor
When stator is excited with a.c voltage, rotating field is set
up
This field produces an EMF in the rotor winding by mutual
induction principle, which in turn circulates current when
the rotor is short circuited
This current interacts with the field produced by the stator
winding, thereby producing torque which is responsible for
the rotation of rotor.
2
3. Construction
Stator :
Consists of core and winding .
It is of cylindrical in structure , made of laminated sheet metal,
build up of laminations.
Laminations are of thickness 0.35mm to 0.5mm
Stator core internal diameter and length are the main
dimensions of induction motor
Rotor:
Types: Squirrel Cage and Wound Rotor
Squirrel cage rotors, consists of uninsulated bars of
aluminium or copper that are joined together at both ends by
rings of similar conducting material
Rotor core is made up of laminated sheet of steel with
thickness of 0.5 mm
3
4. Construction
Aluminium bars and endrings are cased directly over the
rotor core
When copper bars are employed , rotor bar are inserted on
the slots from the end of the rotor and end rings are joined to
them by bracing
Wound rotor – consists of core, winding, sliprings and
brushes.
Rotor core is made of laminations and it carries a three phase
winding
One end of each phase are connected to form a star point
Other end of each phase are connected to three slip rings
4
5. Slip rings are mounted on the rotor shaft and they
are insulated from the rotor and from each other
Carbon brushes are mounted over the slip rings ,
facilitate the connection from rotor winding to the
external resistances
Construction
5
15. Advantages of Squirrel Cage Rotor over Wound
Rotors
i. No slip rings, brushes, short circuiting devices are
required
ii. Higher efficiency
iii. Cheaper and rugged in construction
iv. Has better space factor, shorter over hang, smaller
copper loss
v. Has bare end rings, larger space for fans, thus cooling is
better
vi. Better power factor, pull out torque and overload
capacity
15
16. OUTPUT EQUATION
Out put equation for A.C machines is,
The rating of induction motor is given in Horse Power
16
cosφ
η.
kW
Q
X10
.ac
.B
K
1.1
C
where,
n
L
D
.
C
Q
kVA,
Input
3
-
av
w
o
2
o
η.cosφ
0.746
X
HP
Q
17. CHOICE OF SPECIFIC MAGNETIC LOADING
i. Power Factor: with higher values of Bav in the gap ,
results in large magnetizing current , giving low power
factor. However in I.M Bg should be such that there is no
saturation in any part of the magnetic circuit
ii. Iron loss: an increased in Bav result in increased in iron
loss an decreased in efficiency
iii. Over load capcacity : with increase in Bav, flux per pole
is large. Turns per phase and no of tursn becomes less.
Reduction in leakage reactance. Thereby gives maximum
output for same voltage. So machines has larger over load
capcity
17
18. CHOICE OF SPECIFIC ELECTRIC LOADING
i. Copper loss and temp rise: large value of ac , needs
greater amount of copper , results in higher copper losses
and large temperature rise
ii. Voltage: for high voltage machines , less value of ac should
be chosen, because it needs large space for insulation .
iii. Overload capacity: larger value of ac , results in large
number of turns per phase. Which in turn increase the
leakage reactance of the machine, reduces the overload
capacity of the machine.
18
19. SPECIFIC MAGNETIC & ELECTRIC LOADING:
Bav Specific magnetic loading:
Depends on power factor , iron loss and overload capacity.
For 50Hz machine, Bav – 0.3 to 0.6T.
For machines used in cranes, rolling mills tec., need large
overload capacity Bav- 0.65T
ac :Specific electric loading:
Depends on copper loss, temp rise, voltage rating and
overload capacity.
Varies between 5000 to 45000 ac/m.
19
20. MAIN DIMENSIONS
Separation of D and L depends on the ratio of L/τ ( length
of core to pole pitch)
L/τ = 1.5 to 2 for minimum cost
L/τ = 1.0 to 1.25 for good power factor
L/τ = 1.5 for good efficiency
L/τ = 1 for over all design
Generally L/τ – 0.6 to 2; τ = √0.18L
Diameter of the stator bore and hence diameter of rotor is
also limited by Va.
Va up to 60m/s can be employed
Stator - provided ventilating ducts (L ≥ 125mm) of 10mm
width
20
21. STATOR WINDING
In general double layer lap type winding with diamond
shaped coils is generally used for stators
Small motors with a small no of slots and having large
no of turns per phase may use single layer mush
windings
Three phase of the winding may be connected in either
star or delta depending upon starting methods
employed.
Squirrel cage induction motors - star delta starters
21
22. 22
Stator turns per phase:
Flux /pole Фm = Bav τ L = Bav πDL/P
Stator voltage / phase = Es = 4.44 Kws . f. Фm.Ts
Therefore stator turns / phase
Ts= Es /( 4.44 Kws . f. Фm)
Stator conductors:
X-sectional area of stator conductors can be estimated from the
knowledge of current density, kVA rating and stator phase voltage.
δs – 3 to 5 A/mm2 : Is = Q/(3Es x 10-3)
as = Is/ δs and
Round conductors are used for smaller diameter.
If diameter is more than 2mm, use bar and strip conductors for better
space factor for slots
a
4
d s
s
23. STATOR CORE
Made of laminations of thickness of 0.5mm
Design of stator core involves shape of slots, no. of slots ,
dimensions of teeth and depth of slot
Shape of slot :
Open and Semi-closed slots may be used
When open slots are used, winding coils can be formed and
insulated completely before they are inserted in the slots.
Easy for repair. Avoids excessive slot leakage
Semi-closed slots are usually preferred of I.M because Kg will
be less, results in less magnetizing current, also results in
low tooth pulsation loss and less noise operation
Tapered coils are used in semi closed slots
23
24. 24
In small motors round conductors are used
In large and medium size motors strip conductors are
preferred
In both case tapered slot with parallel sided tooth
arrangement is preferred, because it gives maximum slot
area for particular flux density.
Number of slots :
Depends on tooth pulsation loss, leakage reactance ,
ventilation, magnetizing current , iron loss and cost.
In general no. of slots should be chosen as an integral
For open type slots, slot pitch at the gap – 15 to 25mm
For semi closed slots, the slot pitch may be less than 15mm
STATOR CORE
25. 25
Yss= Gap surface/Total no of slots = π D/Ss
Then Ss=π D /Yss
winding
layer
double
for
Even
–
Z
S
6T
Z
Slot
per
Conductors
slots
stator
of
No.
Condcutors
Stator
Total
Z
Slot
per
Conductors
6T
2T
x
3
conductors
stator
of
no.
Total
phase
per
Conductors
x
phases
No.of
conductors
stator
of
no.
Total
SS
S
S
SS
SS
S
S
STATOR CORE
26. 26
Area of stator slots :
Once no. of conductors per slot has been obtained,
approximate area of the slot can be calculated
Area of the slot = (Copper area/slot)/Space factor
= ZssX ag/Space factor
Space factor - 0.25 to 0.4
High voltage machines have lower space factors
owing to large thickness of insulation.
After obtaining the area of the slot, the dimensions of
the slot should be adjusted
Tooth width and the slot width at gap surface should
be approx equal
STATOR CORE
27. 27
The width of the slot should e so adjusted such that
Bt – 1.3 to 1.7 T.
In general ratio of slot depth / slot pitch- 3 to 6
Length of mean turn
Lmts = 2L + 2.3τ + 0.24
Stator teeth:
The dimensions of the slot determines the value of Bt.
High value of Bt is not desirable, as it leads to a higher iron
loss and greater magnetizing MMF.
Bt should not exceed 1.7 T.
STATOR CORE
28. 28
The minimum width of stator teeth is near the air gap surface or
1/3rd of height of the slots
A check for minimum tooth width using the above equation
should be applied before finally deciding the dimensions of
stator slot
i
S
m
min
ts
ts
i
S
m
L
P
S
1.7
φ
W
.W
L
P
S
/pole
area
Total
tooth
of
Width
length
iron
Net
pole
per
slots
of
No.
/pole
area
Total
1.7
φ
area/pole
tooth
Minimum
STATOR CORE
29. 29
Depth of the stator core :
Depends on flux density in the core,
BCS - 1.2 to 1.5 T
Flux passing through the stator core is
half of the flux per pole.
)
d
2(d
D
D
core,
stator
of
diameter
Outside
L
.
2B
φ
d
core,
of
Depth
(2)
and
(1)
Equating
(2)
d
X
L
core
stator
the
of
Area
also,
(1)
2B
φ
core
stator
in
density
Flux
Core
through
Flux
core
stator
the
of
Area
2
φ
φ
core,
stator
the
in
Flux
Therefore,
cs
ss
o
i
CS
m
CS
CS
i
CS
m
m
c
STATOR CORE
D
dss
Do
dcs
Cross Section of Stator Core
30. LENGTH OF THE AIR GAP
30
lg - decided by considering the following factors:
Power factor
Overload capacity
Pulsation loss
Unbalanced magnetic pull
Cooling
Noise
Power factor:
MMF required to send the flux through the air gap is
proportional to the product of B and lg
Even with small B, MMF required for air gap is much more than
that for the rest of the magnetic circuit.
lg – determines the magnetizing current drawn by the machine.
Magnetizing current inversely proportional to power factor
31. 31
Overload capacity:
lg affects the value of zig-zag leakage reactance which
forms a large part of total leakage reactance .
If lg is larger, then zig-zag leakage flux will be less and so
leakage reactance will be less, results in increase in
overload capacity
Pulsation loss:
With larger length of air gap, the variation of reluctance due
to slotting is small.
The tooth pulsation loss, which is produced due to
variation in reluctance of air gap, is reduced accordingly.
Therefore, the pulsation loss is less with large air gaps.
LENGTH OF THE AIR GAP
32. 32
Unbalanced magnetic pull
If the lg is small, then even for small deflection or eccentricity of the
shaft would produce large irregularity in lg .
It is responsible for the production of UMP, which has the tendency to
bend the shaft still more at a place where it is already bent resulting in
fouling of rotor with stator.
If lg is large, a small eccentricity would not able to produce noticeable
UMP.
Cooling:
If lg is large, cylindrical surfaces of rotor and stator are separated by a
large distance.
This would afford better facilities for cooling at the gap surfaces
especially when a fan is fitted for circulation of air
Noise:
The principle cause of noise in I.M is the variation of reluctance of the
path of the zig-zag leakage as small as possible, can be done by
increasing lg.
LENGTH OF THE AIR GAP
33. Relations for length of air gap
33
i. For small I.M , lg = 0.2 + 2√DL mm
ii. Alternate formula for small Induction Motors,
lg = (0.125 + 0.35 D + L + 0.015Va ) mm
iii. For general use, lg = (0.2 + D) mm
iv. For machines with journal bearings
lg = 1.6 √D – 0.25 mm
D,L and Va are in meters
D in mm lg in mm
0.15 0.35
0.20 0.50
0.25 0.60
0.30 0.70
0.45 1.30
0.55 1.80
0.65 2.50
0.80 4.00
34. DESIGN OF SQUIRREL CAGE INDUCTION ROTOR
34
The squirrel cage rotor consists of laminated core, rotor
bars and end rings
The rotor bars and end rings are made of Al or Cu
lr is same as that of stator
Diameter of the rotor is slightly lesser than the stator to
avoid mechanical friction between the stationary stator and
rotating rotor
Rotor diameter Dr = Stator Bore(D) – 2lg
35. DESIGN OF ROTOR BARS AND SLOTS
35
For a three phase machine , the rotor bar current is given
by the equation,
Rotor bar current Ib =(6Ts.Is)Kws cosФ/Sr
o.85(6Ts.Is)/Sr
Performance of an induction motor is greatly influenced by
the resistance of the rotor
Higher rotor resistance has higher starting torque but
lesser efficiency
Rotor resistance is the sum of resistance of the bars and
the endrings
The cross section of the rotor bars and end rings are
selected to meet both requirements of Tst as well as
efficiency
36. 36
Current density of the rotor bar,δb - 4 to 7 A/mm2
Area of each rotor bar, ab = Ib/ δb mm2
In case of squirrel cage motor the X-sectional area of bars will
take the shape of the slot and insulation is not used between bars
and rotor core.
The rotor slots for squirrel cage rotor may be either closed or
semi closed types.
Advantages of closed slots:
Low reluctance
Less magnetizing current
Quieter operation
Large leakage reactance and so starting current is limited
Disadvantage of closed slots:
Reduced overload capacity
DESIGN OF ROTOR BARS AND SLOTS
37. 37
Rules for Selecting Rotor Slots:
i. No. of stator slots should never be equal to rotor slots.
Sr is 15% less than Ss
ii. The difference (Ss-Sr) should not be equal to ± P, ±2P or ±
5P to avoid synchronous steps
iii. The difference (Ss-Sr) should not be equal to ±3 P to
avoid magnetic locking
iv. The difference (Ss-Sr) should not be equal to ± 1, ±2 ,± (p
± 1) or ,± (p ± 2) to avoid noise and vibrations
DESIGN OF ROTOR BARS AND SLOTS
38. DESIGN OF END RINGS
38
The distribution of current in the bars and end rings of a
squirrel cage motor is complicated
It can be shown that if flux distribution is sinusoidal then the
bar current and end ring current will also be sinusoidal
Max. value of end ring current
However , current is not maximum in all the bars under one pole
at the same time but varies according to sine law
Hence the max. value of the current in the end ring is the
average of the current of half the bars under one pole
b(max)
r
e(max)
I
2p
S
Bar
per
Current
X
2
Pole
per
Bars
I
39. 39
Maximum value of end ring current,
Current density of the end ring δe - 4 to 7 A/mm2
Ae= Ie/ δe mm2
also Ae = Depth of end ring X Thickness of end rings = de X te
πp
S
I
2
I
2
π
2
2p
S
I
π
2
2p
S
I
2
pole
per
Bars
I
r
b
b
r
b(max)
r
b(ave)
e(max)
DESIGN OF END RINGS