EE411.FinalExam.spring01

EE411.FinalExam.spring01 - EE411, Final Exam, 5/12/01. Show...

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Unformatted text preview: EE411, Final Exam, 5/12/01. Show All Work On These Pages. Name: 2‘2 Problem 1. Find the Thevenin equivalent circuit for terminals a-b. [‘30 D a 161QtA 250 —1500 150 b 0’66 1 — M0 deflemoém+ somech Wem‘mg £13036.) OPP/t) Cl‘k‘cMi-l-‘I‘Ngt ‘Hlfl CHK£€N+ $0Mfl¢¢>j +AP/U 2TH: .0339“ (330525 +13) : alsoHQowgo) ' ,E‘Soétowt'fio) «v .420004—500 RSOOZLSéB .2: TH 150” 027??) 40 a)” ' 44421-2657 EE411, Final Exam, 5/12/01. Show All Work On These Pages. Name: :1 Problem 2. The switch has been open a long time. Then, at t = 0, it Closes. a. Find the stored energy in the L at t = 0+, and in the C at t = 0". b. Find the stored energy in the L as t —>00, and in the C as t —>00. 1500 Moo) ~ - “Mym. mm. 0 /_//,,Wfl 1 L1 Z> 12(3 (X/D'3)('0¢‘)Z= OJbSWO 3 EE411, Final Exam, 5/12/01. Show All Work On These Pages. Name: \ Problem 3. A three-phase, 60Hz, motor has internal windings connected in delta. Three external wires, a-b-c, connect the motor terminals to a power source. The motor operates with the following balanced conditions: - Line-to-line rms voltage = 460V (the corresponding line-to- neutral rrns voltage is 265.6V) 0 Input P = 10kW, with power factor = 0.90 (lagging current) External wires To Power Source a. Determine the rrns current magnitudes in the external a-b-c wires that connect to the power source. b. Determine the rms current magnitudes in the delta-connected motor windings. Now, assume that the voltage at the motor terminals is always 460V. Three capacitors are to be connected in delta at the motor terminals to correct the net power factor to unity. What should be the MF value of each capacitor? d Determine the new rms currents in the external a—b-c wires after the capacitors are added. .0 . . ~ I @ 716 0N6’IINQ oI/figfifim :5 "3+ whim-3 33K“) M M hfisfl .laV “3 3 @3213“: E50518: of 5W“ 63;? 6a“ ‘ "WM e. A - ' av _ , _, FKOM VLM I’{M"’§¢¢p ‘ MM, '9‘? EE411, Final Exam, 5/12/01. Show All Work On These Pages. Name: E E Z Problem 4. Voltage Vdc is adjustable. Find the value of vdc that causes current iO to be zero. f I}; 300 —> go [/3 9V3 ...
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EE411.FinalExam.spring01 - EE411, Final Exam, 5/12/01. Show...

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