This document contains a semester examination for an Electrical Machine Design course. It includes 5 questions assessing various topics related to electrical machine design:
1) Expressions for armature m.m.f and apparent flux density in a DC machine.
2) Heating time constant evaluation from heating curves and transformer temperature rise calculations.
3) Core dimensions for square and cruciform sections and reasons for preferring circular coils.
4) Ratio of iron to copper weights for minimum cost and transformer dimensions.
5) Specific magnetic and electric loadings, output coefficient, and induction motor main dimensions.
Roof Truss Design (By Hamza Waheed UET Lahore )Hamza Waheed
This presentation defines, describes and presents the most effective and easy way to design a roof truss with all the necessary steps and calculations based on Allowable Stress Design. Soft-wares like MD Solids, Truss Analysis have been used. It is most convenient way to design a roof truss which is being the most important structural components of All types of steel bridges.
Roof Truss Design (By Hamza Waheed UET Lahore )Hamza Waheed
This presentation defines, describes and presents the most effective and easy way to design a roof truss with all the necessary steps and calculations based on Allowable Stress Design. Soft-wares like MD Solids, Truss Analysis have been used. It is most convenient way to design a roof truss which is being the most important structural components of All types of steel bridges.
A fuel cell uses the chemical energy of hydrogen or another fuel to cleanly and efficiently produce electricity. If hydrogen is the fuel, electricity, water, and heat are the only products. Fuel cells are unique in terms of the variety of their potential applications; they can provide power for systems as large as a utility power station and as small as a laptop computer. Fuel cells can be used in a wide range of applications, including transportation, material handling, stationary, portable, and emergency backup power applications. Fuel cells have several benefits over conventional combustion-based technologies currently used in many power plants and passenger vehicles. Fuel cells can operate at higher efficiencies than combustion engines and can convert the chemical energy in the fuel to electrical energy with efficiencies of up to 60%. Fuel cells have lower emissions than combustion engines. Hydrogen fuel cells emit only water, so there are no carbon dioxide emissions and no air pollutants that create smog and cause health problems at the point of operation. Also, fuel cells are quiet during operation as they have fewer moving parts. This work is a representation of Ansys capabilities to simulate fuel cell for academic learning .
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.
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.
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Learn about the cost savings, reduced environmental impact, and minimal disruption associated with trenchless technology. Discover detailed explanations of popular techniques such as pipe bursting, cured-in-place pipe (CIPP) lining, and directional drilling. Understand how these methods can be applied to various types of infrastructure, from residential plumbing to large-scale municipal systems.
Ideal for homeowners, contractors, engineers, and anyone interested in modern plumbing solutions, this guide provides valuable insights into why trenchless pipe repair is becoming the preferred choice for pipe rehabilitation. Stay informed about the latest advancements and best practices in the field.
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
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
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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
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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.
Immunizing Image Classifiers Against Localized Adversary Attacks
160512 160804-electrical machine design
1. 1
Seat No.: _____ Enrolment No.______
GUJARAT TECHNOLOGICAL UNIVERSITY
BE- VIth
SEMESTER–EXAMINATION – MAY- 2012
Subject code: 160804 Date: 17/05/2012
Subject Name: Electrical Machine Design
Time: 10:30 am – 01:00 pm Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Q.1 (a) Deduce an expression for the m.m.f required for the air gap of an
armature with slots and ducts.
07
(b) Determine the apparent flux density in the teeth of a d.c.machine having
the following data:
Real flux density = 1.95 Wb/m2
Slot pitch = 2.8 cm
Slot width = 1.0 cm
Gross core length= 35 cm
Ventilating ducts = 5
Width of each duct= 1.0 cm
Stacking factor = 0.9
Use the following magnetization curve:
Flux-density: Wb/m2
1.7 1.8 1.9 2.0
Mmf per metre
(Amps).
10,000 19,000 34,000 100,00
07
Q.2 (a) Define heating time constant and explain how it can be evaluated from
heating curve.
07
(b) During a heat run test of a 100 KVA transformer the temperature rise
after 1 hour and 2 hours is found to be 24ο
C and 34 ο
C respectively.
Calculate the heating time constant and final steady temperature rise.
If the cooling is improved by using an external fan so that the rate of
heat dissipation is increased by 18%, find the new KVA rating for the
same final temperature rise. Assume that the maximum efficiency occurs
at 80% of full load and unity power factor.
07
OR
(b) A 30 MVA alternator has a total loss of 1000 Kw.The temperature rise in
the machine is limited to 30 ο
C.Assume
Inlet air temperature = 25 ο
C
Barometric height = 780 mm of mercury.
Pressure = 20 cm of water
Fan efficiency = 40%
Specific heat of air at constant pressure = 0.237 cal/gm- ο
C
Volume of 1kg of air at 0 ο
C and 760 mm of mercury=0.775 m3
.
Calculate the volume of cooling air required and also the fan power.
07
Q.3 (a) Deduce an expression for the design of core for Square and cruciform
sections also state the reason why circular coils are always preferred in
comparison to rectangular coils.
07
(b) Determine the dimensions of the core and yoke for a 100 KVA, 50 Hz,
Single phase, core type transformer. A square core is used with distance
07
2. 2
between the adjacent limbs equal to 1.6 times the width of the
laminations. Assume voltage per turn of 14 volts, maximum flux density
1.1 wbm2
, window space factor 0.32 and the current density 3A/mm2
.
Take stacking factor = 0.9.Flux density in the yoke to be 80% of flux
density in core.
OR
Q.3 (a) Show that for minimum total material cost of a 3-phase transformer the
ratio (Weight of iron/Weight of copper) should be equal to the ratio
(specific cost of Copper (Rs. /kg) / specific cost of iron ((Rs. /kg)).
07
(b) Determine the main dimensions of the core, the number of turns and the
area of conductors for a 5 KVA, 50 Hz, 11000/400 V, Single phase, core
type distribution transformer. The net conductor area in the window is
60% of the net cross-section (square) of the iron core. Assume a flux
density of 1 wb/m2
, a current density of 1.4 A/mm2
and a window space
factor of 0.2.The window height is 3 times its width.
07
Q.4 (a) Define specific magnetic loading (Bav) and specific electric loading (ac)
and obtain an expression for the “output co-efficient for a d.c. machine.
07
(b) Calculate the main dimension of a 250 h.p., 3-ph., 50 Hz, 400V, 1410
rpm, delta connected slip-ring induction motor. The data given are:
Bav= 0.5 Wb/m2
, ac=30000 A/m
Efficiency and power-factor, both = 90 %;
Winding factor =0.955; current density = 3.5 A/mm2
Slot space factor = 0.4 ,
ratio of core length to pole pitch =1.2
07
OR
Q.4 (a) Discuss the factors that determine the choice of air-gap in induction
motor.
07
(b) Find the main dimensions and numbers of poles of a 50 h.p., 230 V, 1400
rpm shunt motor so that a square pole face is obtained. Bav in the gap is
0.5 wb/m2
and the amp-conductor per meter are 22,000.The ratio of pole
arc to pole pitch is 0.7.Assume the efficiency of the machine as 90
percent.
07
Q.5 (a) What are the important considerations in choosing number of poles in
d.c. machine?
07
(b) List and explain briefly the limitations being imposed in the design of
electrical machines also discuss the modern trends in the design.
07
OR
Q.5 (a) What are the types of windings commonly used in transformer and on
what basis are they selected?
07
(b) Explain the methods for the estimation of Mmf for the tapered teeth. 07
*************