Electric machinery fundamentals
5th Edition
ISBN: 9780073529547
Author: Chapman, Stephen J.
Publisher: MCGRAW-HILL HIGHER EDUCATION
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Question
Chapter 1, Problem 1.17P
(a)
To determine
The reasonable maximum flux density for the given core.
(b)
To determine
The total flux in the core for the given flux density.
(c)
To determine
The reasonable number of turns which provide the required flux density for the given case.
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Q2) In DC machine, the speed is 800 RPM, the flux per pole is 2 m wb, and it has a Lap winding
armature with 6 coils (4 turns conductor per coil) . The DC machine has 2 poles and armature draws
lc= 5.5 A. If the winding redesigned as wave winding, find the EA , Tem and Pem and explain
what will happen when we change the design from lap to wave winding connection.
A 4 pole armature of a DC machine has 175 conductors and a flux per pole of 0.1 wb. Find the EMF generated when running at 600 rpm, when the armature is Lap wound.
The armature of a 6 pole, lap wound dc machine has 54 slots. Each coil has 15 turns. The average flux density is 1.2 T. The armature length is 15 cm and the diameter is 30 cm. The magnetic poles are designed to cover 90% of the surface area. If the armature speed is 1200 rpm, determine the(i) induced emf in the armature winding (ii) induced emf in the coil(iii) induced emf per turn induced (iv) emf in each conductor(v) What is the power and torque if each conductor is rated at 10 amps?(vi) Which of the above values would change if the generator was wave connected?
Chapter 1 Solutions
Electric machinery fundamentals
Ch. 1 - What is torque? What role does torque play in the...Ch. 1 - What is Amperes law?Ch. 1 - What is magnetizing intensity? What is magnetic...Ch. 1 - How does the magnetic circuit concept aid in the...Ch. 1 - What is reluctance?Ch. 1 - What is a ferromagnetic material? Why is the...Ch. 1 - How does the relative permeability of a...Ch. 1 - Prob. 1.8QCh. 1 - What are eddy current losses? What can be done to...Ch. 1 - Why are all cores exposed to ac flux variations...
Ch. 1 - What is Faraday law?Ch. 1 - What conditions are necessary for a magnetic field...Ch. 1 - What conditions are necessary for a magnetic field...Ch. 1 - Prob. 1.14QCh. 1 - The linear machine in Figure 1-19 is running at...Ch. 1 - Just how does a decrease in flux produce an...Ch. 1 - Will current be leading or lagging voltage in an...Ch. 1 - What are real, reactive, and apparent power? What...Ch. 1 - What is power factor?Ch. 1 - Prob. 1.1PCh. 1 - A flywheel with a moment of inertia of 4kgm2 is...Ch. 1 - A force of 10 N is applied to a cylinder of radius...Ch. 1 - A motor is supplying 50Nm of torque to its load....Ch. 1 - A ferromagnetic core is shown in Figure P1-2. The...Ch. 1 - A ferromagnetic core with a relative permeability...Ch. 1 - A two-legged core is shown in Figure P1-4. The...Ch. 1 - A core with three legs is shown in Figure P1-5....Ch. 1 - A two-legged core is shown in Figure P1-4. The...Ch. 1 - A wire is shown in Figure P1-7 that is moving in...Ch. 1 - Repeat Problem 1-10 for the wire in Figure P1-8.Ch. 1 - Prob. 1.12PCh. 1 - A core with three legs is shown in Figure P1-10....Ch. 1 - A two-legged magnetic core with an air gap is...Ch. 1 - A transformer core with an effective mean path...Ch. 1 - The core shown in Figure P1-2 has the flux shown...Ch. 1 - Prob. 1.17PCh. 1 - Prob. 1.18PCh. 1 - Prob. 1.19PCh. 1 - Demonstrate that Equation (1-59) can be derived...Ch. 1 - Prob. 1.21PCh. 1 - Prob. 1.22PCh. 1 - For the linear machine of Problem 1-22: When this...
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- DC MACHINE TORQUE The armature of a dc motor has 648 conductors, 65 % of which are directly under thepole where the flux density is 48,000 lines per in2. If the core diameter is 7 inchesand its length is 4 inches and the current in each conductor is 20 A. What is thetorque exerted in the armature in N-m?arrow_forwardThe resistance of the field winding(copper wire) of a DC machine is 0.25 ohm at 25°C. When operating at full-load, the temperature of the winding is 75 °C. The temperature coefficient of resistance of copper is 0.00427 per °C at 0°C. Find the resistance of the field winding at full-load.arrow_forwardIn a DC machine, the air gap flux density is 4 Wb/m2. The area of the pole face is 2 cm x 4 cm. Find the flux per pole in the machine.arrow_forward
- A DC machine has total armature ampere conductors of 4500 and total flux in the machine is 0.14 wb. The torque developed in the machine is (in N-m/rad)arrow_forward× 4:03 K s.eng.ruh.ac.lk □ Û 8. Figure 4 shows the core of a simple dc motor. The magnetization curve for the metal in this core is given by Figure 5 and Figure 6. Assume that the cross-sectional area of each air gap is 18 cm² and that the width of each air gap is 0.05 cm. The effective diameter of the rotor core is 4 cm. L It is desired to build a machine with as great a flux density as possible while avoiding excessive saturation in the core. What would be a reasonable maximum flux density for this core? ii. What would be the total flux in the core at the flux density of part (i)? iii. The maximum possible field current for this machine is I A. Select a reasonable number of turns of wire to provide the desired flux density while not exceeding the maximum available current. Flux Density, B (T) 2.8 སྤྲ ཤཱ ཀ ཀཱ བྷ ཀ ཡཱཾ བ ་ 1.2 1.0 0.4 0.2 4-48cm Figure 4 0 10 20 30 40 50 100 → Depth 4 cm -0.05 cm 200 300 500 1000 2000 Magnetizing Intensity, H (A.turns/m) Figure 5 Magnetization curve…arrow_forwardDetermine the power output of a DC armature having 1152 lap connected conductors carrying 150 A and rotating at 300 rpm in a 12 pole field. The flux per pole is 60 mwb.arrow_forward
- Topic Electrical Machines - Magnetic & E... For a coil, each turn faces (2t4 – t³ – 2t) milliwebers of flux. The value of induced EMF in coil for 100 turns coil at 2 sec is, (in Volts).arrow_forwardSOLVE AND SHOW YPUR COMPLETE SOLUTION. ANSWERS SHOULD BE IN TWO DE CIMAL PLACES. The armature of a two-pole dc machine has 30 slots, each slot has 4 conductors each. during its operation, only 75% of the conductors are directly under the pole. each pole measures 2 inches by 3 inches and produces ten million maxwells of flux. the armature core is 12 inches in length and 3.5 inches in diameter. the total resistance of the winding is 2 ohms. a) determine the frequency of the machine when running at 3600 rpm.arrow_forwardThe armature of a dc motor has 648 conductors, 65 % of which are directly under the pole where the flux density is 48,000 lines per in2. If the core diameter is 7 inches and its length is 4 inches and the current in each conductor is 20 A. What is the torque exerted in the armature in N-m?arrow_forward
- The magnetization curve of a DC machine is linear. True or Falsearrow_forward2. A six-pole lap wound armature rotating at 350 rpm is required to generate 260 V. The effective flux per pole is about 0.05 Wb. If the armature has 120 slots, determine the suitable number of conductors per slot and hence determine the actual value of flux required to generate the same voltage.arrow_forwardAn 2 pole, wave connected armature has 550 conductors and its generated e.m.f is 110 V. If the machine is driven at 600 rpm, then the flux per pole in Wb is,arrow_forward
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