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Unformatted text preview: EE321. ABET Exam Spring 2004 Name: Student ID: Instructions: Work ALL Problems. When you have completed exam, turn in to Professor Sudhoff, Brandon Cassimere, or Brant Cassimere, any of whom will check it on the spot, and let you know which ones are wrong if you need to revise any problems. The last possible moment to turn in the exam is immediately prior to the final exam (at which point you will not have the opportunity to revise your work). All problems must be worked correctly in order to be eligible for a passing grade in the course. Problem 1 Magnetic Equivalent Circuits and Design of Electromechanical Devices Consider the electromagnet shown in Figure 1 (back page). Suppose that b d is very thick, so that the reluctance associated with the top (and bottom) may be ignored. Further suppose c r is 1 cm, and s w is 2 cm, and s d is 2 cm, and g is 0.1 mm. In this problem, neglect fringing flux. The relative permeability of the steel is 1000. Determine the following: (a) What should e t be in order to keep the flux density the same in the center post as in the edge area ? (b) With the value of e t from part (a), if the flux density in the center post is to be limited to 1.1 Tesla, what is the maximum product of turns and current ( Ni ) (c) Derive an expression for the resistance of the winding in terms of s d , s w , c r , N , the packing factor pf , and the resistivity of the conductor...
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This note was uploaded on 02/19/2012 for the course ECE 321 taught by Professor Staff during the Spring '08 term at Purdue UniversityWest Lafayette.
 Spring '08
 Staff
 Electromagnet

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