Earth Is the Lords
5th Edition
ISBN: 9781121660069
Author: Caldwell, Taylor
Publisher: MCG/CREATE
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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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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?
Suppose that we are designing a 1200-rpm dc motor to run from a 240-V source. We have determined that the flux density will be 1 T because smaller fluxes make inefficient use of the iron and larger fluxes result in saturation. The radius of the rotor (and thus, the torque arm for the armature conductors) is 0.1 m. The lengths of the armature conductors are 0.3 m. Approximately how many armature conductors must be placed in series in this machine?
The current in a conductor on the armature of a dc motor is 300A. The flux under the poles is 850x10-6 Wb. The area per pole is 700 mm2. The length of the conductor on the armature is 640mm. Calculate the force exerted on the conductor.
Chapter 1 Solutions
Earth Is the Lords
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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- The 4-pole direct current electric machine works as a generator. In this direct current machine, which also has auxiliary poles, the direction of the excitation flux is from bottom to top at the remaining pole located at the top of the armature from the main poles on the d axis. As the current direction is ๏ in armature conductors corresponding to the same pole; a. Find the direction of flux at the main poles.b. Find the current direction at the main polesc. Find the direction of flux at the auxiliary poles.d. Find the current direction at the auxiliary poles.e.Show the direction of rotation by drawing a figure.arrow_forwardConsider the linear dc machine shown in Figure 15.6 on page 754. What happens to the initial force (i.e., starting force) induced in the bar if: a. the source voltage VT is doubled in magnitude; b. the resistance RA is doubled; c. the magnetic flux density B is doubled in magnitude?arrow_forwardConsider the linear dc machine shown in Figure 15.6 on page 754 with no load force applied. What happens to the steady-state velocity of the bar if: a. the source voltage VT is doubled in magnitude; b. the resistance RA is doubled; c. the magnetic flux density B is doubled in magnitude?arrow_forward
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