Exam_4_Solution - NAME jam 7/ 0R STUDENT NUMBER: April 16,...

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Unformatted text preview: NAME jam 7/ 0R STUDENT NUMBER: April 16, 2008 ECE 320, EXAM 4 Spring 2008 Problem 1 A 64—pole Y—connected synchronous generator is rated SOMVA, ZOkV, pf = 0.85 lagging, Ip/if z 25 and it has Lrn :1989 mH. 1:) {m t: :7. 5J1 3. Calculate the rated stator current and field current. Draw the corresponding phasor diagram for this operating point. i ' 4 —3/. '0 2% .50 /0 F ‘ [J7 $5727 A J;=/c/95 A \0 b. Suddenly all the power to the generator is removed, the generator is still connected to the same power system of ZOkV and the field current remains unchanged (rated). What will be the stator current and the power factor? Include phasor diagram in your solution. 7’ = 5V3 19 cos '3’ "‘0 "3 (2° : qoo 5‘9) mo ._. t3“ —— * —-— Tar-2:210 a ) .Lm: IBHO A 11;;— film-{,2 PI; —-— O Problem 2 A BLDC machine is supplied from 120V and under mechanical load at 1800 RPM draws 17A of current. The same machine operated from 120V and no—load will Spin at 3133 RPM. a. What is the resistance of the machine and torque at the given load? (neglecting friction) . 2‘1? @ no Load V: Wk ‘20 V: —‘—E‘O‘—‘ l6; M:O./5(-9é7 v6 Tzk : 0.36647- "1622“;41 @ Legal V: UL +1043 =3 iaovzt‘i-R+o%°l§‘é Re- 3-51— b. What is the no-and torque? (neglecting friction) @ no Lead Po "Tau Problem 3 a. What is the purpose of field weakening mode in PMAC motors? to ofcrcfie Aha, madmxfla CZX‘ hqher b. List one advantage and one disadvantage of PMAC machine versus 1M. @ [/3166 [MK Fflf' @ Offf/Céfgié like “Va/4:5. , ...
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This note was uploaded on 09/21/2010 for the course ECE 320 taught by Professor Jurkovic during the Spring '08 term at Michigan State University.

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Exam_4_Solution - NAME jam 7/ 0R STUDENT NUMBER: April 16,...

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