EECE 210 Exam 2, Fall 2000

www.amal-aub.org Profs, N. Sabah FACULTY OF ENGINEERING FALL TERM 2¢ R. Chedid & ARCHITECTURE L. Chaar i. Mougharbel NOV’ , 20 =] ={ Ww “sj ea se] NS > > oS (ELEG 310) ELECTRIC CIRCUITS CLOSED BOOK (1% HRS) Programmable Calculators are not allowed Provide your answers on the computer’s card only Return the computer’s card attached to the question sheet Mark with a pencil your name and your ID-No Use pencil for marking your answers When using eraser, be sure that you have erased well it PENALTY IS6 TO t Test ID 2000- 1/5 www.amal-aub.org Profs. N. Sabah FACULTY OF ENGINEERING R. Chedid & ARCHITECTURE iL. Chaar I. Mougharbel (ELEG 310) ELECTRIC CIRCUITS CLOSED BOOK (1 % HRS) Programmable Calculators are not allowed Provide your answers on the computer’s card only Return the computer’s card attached to the question sheet Mark with a pencil your name and your ID-No Use pencil for marking your answers When using eraser, be sure that you have erased well it! PENALTY IS6TO1 Mm! FALL TERM 2¢ NOV ,20 Test ID 2000- 1/5 www.amal-aub.org 1. An impedance Z1= (4+)4) Q is connected in parallel with an impedance Z2= (12+)6) ©. If the input reactive power is 1000 VAR (lagging), what is the total active (average) power ? A. 1210 W B. 3025 Ww C. 826.39 W D. 1150 W E. None of the above 2. In the circuit shown below, find the Thevenin equivalent circuit as seen from terminals a-b. Gre Flo Pr WW {at— ae AN o a phe > ‘Bose jogo (e | V i ab Vrhev= 4.82< 34.60, V, Zthev= 8.62<40.38 Q Vthev= 48.2<-34.60, V, Zthev= 86.2<48.79 Q Vrhev= 5<-34.60, V, Zthev= 8.1<48.79 Q Vthev= 4.82<-34.60, V, Zthev= 8.62<48.79 Q None of the above MOOm> 3. The conjugate of the complex power delivered by a current source is 200 ~/200 VA. If the source current is 88 A peak, determine the rms voltage across the source. 40 Vrms /40 V rms 80 V rms —j40 V rms None of the above MOOD www.amal-aub.org 4. In the figure shown, vs = 10cos100nt V rms, > L1= 120 mH, Lo = 30 mH, R= 100 ohms, N; = 500 turns, and Nz = 1500 turns. Determine + the coupling coefficient so that no current flows M R No in the 100 ohm resistor. ; Vs =" NA, . wea e ) A. 0.4 CA PIOES Lr 2 EL, Ny B. 0.5 a: _ C. 0.6 ~ D. 0.8 E. None of the above Zz ty 5. Given a balanced three-phase system in which a a the load consumes 50 kW at 0.8 p.f. lagging. The b lL TI} boad line impedance Z, = 0.5 + / 0.5 Q. Capacitors are ee aa on connected at the load terminals so that the p.f. c oe a at the supply terminals abc is unity. If the line current / is 100 A rms, determine the rms line voltage at the load terminals. (Answers are rounded to three significant figures.) A. 579V rms B. 367 Vrms C. 301 Vrms D. 262 Vrms E. None of the above 6. Find the maximum average power given that R, is adjusted for maximum power transfer. A.3e6W B. goo W C.900 W D. 25 W E. None of the above Test ID 2000- 3/5 www.amal-aub.org 7. A three-phase line has an impedance of (0.1 +] 0.8) £2/, the line feeds two-balance three- phase load connected in parallel. The first load absorbs a total of 540 kW and 720 KVAR. The second load is Y connected and has an impedance of 20 ~—] 6.67 Q/6, the line-to- neutral voltage at the load is 4 KV ims. Find the line voltage at the source. . 6990.63 V 6973.6 V 6987.47 V 6951.82 V None of the above MOoOm>s Given: Vs = 300 <0° V, Z1=j3600 Q, Z2=j2500 Q, Zm=j1200 Q, Zc= -}1800 A. I1= 132 <+99° mA, 12=333<-90° mA B. I1= 132 <9° MA, 12=333<+189° mA C. I1= 280 <-g9° MA, 12=560<+90° mA D. I1= 280 <9? MA, 12=560<+180° mA E. None of the above A. 0.97 lagging B. 0.89 lagging C. 0.97 leading D. 0.89 leading E. None of the above Test ID 2000- 4/5 www.amal-aub.org 10. Find the input impedance Zag in the circuit shown below. (or Jar A ban oe MM. Raa y A. 6.14+35Q : * B. 38+j920 G0L0 da” ae Jor C. 6+j5.8969 v D. 83+j479 e E. None of the above gB “K20.224 11. Determine the value of C in the circuit shown if C takes 5 VAR. The operating frequency is 50 Hz. Gu VA. (220° SL 30/0 Vv cam Vv A. 12.63 uF Q 62 B. 14.74 uF J°-628.2 C. 17.68 uF _ D. 3 uF E. None of the above