Republic of the Philippines Professional Regulation Commission Board of Electrical Engineering Electrical Engineering Board Examination E2 8:00 am – 12:00 noon PROFESSIONAL ELECTRICAL ENGINEERING SUBJECTS SET A INSTRUCTION: Select the correct answer for each of the following questions. Mark only one answer for each item by shading the box corresponding to the letter of your choice on the answer sheet provided. STRICTLY NO ERASURES ALLOWED. Use pencil no. 1 only. NOTE: Whenever you come across a caret (^) sign, it means exponentiation. Ex. x^2 means x2; (x+y)^(x-z) means (x+y) raised to the (x-z). Pi=3.1416 MULTIPLE CHOICE 1. Find the impedance which requires 1549 VAR AT 230 V rms and 10 A rms. A. 17.40 - j15 ohms C. 17.09 - j15.39 ohms B. 16.82 – j15.69 ohms D. 17.62 – j14.78 ohms 2. For a series RLC circuit with elements R = 50 Ω, L = 8 mH and C = 2.22 μF. What is the equivalent impedance of the circuit if its frequency is 796 Hz? A. 50 – j50 ohms C. 50 + j130 ohms B. 50 + j50 ohms D. 50 – j130 ohms 3. Find the current that will follow in a series circuit containing a 5 kohm resistor, a 470 picoF capacitor, a 150- mH inductor, and a 0.001 microfarad if the exciting voltage is 65 volts at 25kHz. A. 6.32 +j8.46mA C. 8.46+j6.22mA B. 6.22-8.46mA D. 8.46-j6.22mA 4. Two impedances, Z1=0.8+j5.6 and zZ2=8-j16 and the single phrase motor are connected in parallel across 200 Vrms. 60Hz supply. The motor draws 5 kVA at 80% power factor lagging. Find the complex power of impedance Z2? A. -1-j2kVA C. 2+ j1kVA B. 1-j2kVA D. -2-j1kVA 5. What are the two elements in a series circuit connection having a current and voltage i= 13.42 sin (500t-53.4degrees) A and v= 150sin (500t+10degrees) V? A. R= 8.8 ohms and L=35mH C. R= 6.3 ohms and L=25mH B. R= 7.5 ohms and L=30mH D. R= 5.0 ohms and L=20mH 6. The impedance Z3 in series to the two impedances Z1= 10+ j10 ohms and Z2= 20j30 ohms that are connected in parallel. What is the value of the impedance Z3 in ohms that will produce resonant circuit? A. –j13.1 C. j13.1 B. j5.4 D. –j5.4 7. One hundred picofarad capacitor is connected in series with a coil having inductance of 100μH and a resistance of 100 ohm. At what frequency will this network have at unity pf. A. 1.4 MHz C. 1.8 MHz B. 1.2 MHz D. 1.6 MHz 8. A 125-F capacitor that has a n initial voltage of 25-V is charge with a current that varies with time according to the equation i = t (t2+6.83)1/2. Find the voltage across the capacitor at 1 s. A. 26 V C. 25 V B. 20 V D. 20.2 V 9. Find the current through a 0.1 microfarad capacitor at t = 0, if the voltage across it is -2 e-10^7t V. ELECTRICAL2/Page 1 Republic of the Philippines Professional Regulation Commission Board of Electrical Engineering Electrical Engineering Board Examination E2 8:00 am – 12:00 noon PROFESSIONAL ELECTRICAL ENGINEERING SUBJECTS A. 200 mA B. 20 mA SET A C. 20 A D. 2 A 10. A balanced three-phase wye-connected load of 100 A, when the line is 2400 V, 60 Hz. A. 21 Mf C. 205 B. 21 μF D. 205 of 150 kW takes a leading current What is the capacitance per phase? mF μF 11. A balanced delta connected load of 4 – j3 ohms per phase is fed by a 380 V, three-phase system. Find the reactive power. A. 52 kVARS C. 69 kVARS B. 29 kVARS D. 87 kVARS 12. The phase currents in a wye-connected unbalanced load are la – 44 – j33, lb = -32 – j24, and lc = -40 + j25 A. What is the positive sequence current for phase A? A. -28 – j21 A C. 28 – j31 A B. 40.8 + j8.9 A D. 40.8 – j8.9 A 13. A 240 V (line to neutral) three-phase source is connected to three 10 ohm resistance loads with both source and load in the Y-configuration. Determine the current in each phase A. 22 A C. 24 A B. 20 A D. 28A 14. A balanced three-phase wye connected source has using positive phase sequence. Van = 220 V rms with 30 degrees angle. Determine Vbc. A. 190.5 + j330 V C. -190.5 – j330 V B. 190.5 – j330 V D. – j381 V 15. In a balanced three-phase system, the wye-connected impedances connected are 10 ohms with 30 degrees angle. If Vbc is equal to 416 V with 240 degrees angle, determine Icn. Assume the phase sequence is abc. A. 12 + j20.8 A C. 12 – j20.8 A B. 20.8 – j12 A D. 20.8 + j12 A 16. Given the following phase currents, Ia = 3.5 + j3.5, Ib = 0 – j3 and Ic = -2.6 + j1.6. determine the negative sequence current for phase A. A. 0.333 + j0.678 C. 0.424 + j0.571 B. -0.333 – j0.678 D. -0.333 + j0.678 17. Given the following sets of symmetrical components currents, determine the phase B current. Current Magnitude Angle, degrees Ia0 1.0 75 La1 1.0 15 La2 1.0 -45 A. 0.259 + j0.966 C. 1.932 + j0.518 B. 0.516 + j1.931 D. 1.414 + j1.414 18. A transformer having a 360 turn primary winding takes 150 W in power and 1.4 A in current at an input voltage of 230 volts. Determine the no-load power factor. A. 0.606 C. 0.466 B. 0.866 D. 0.523 19. A transformer when it is operated as a conventional two winding transformer ELECTRICAL2/Page 2 Republic of the Philippines Professional Regulation Commission Board of Electrical Engineering Electrical Engineering Board Examination PROFESSIONAL ELECTRICAL ENGINEERING SUBJECTS E2 8:00 am – 12:00 noon SET A is rated 10 MVA, 12/1.2 kV, 60 Hz. Under these conditions, its series resistance and reactance are given as 2% and 7% pu respectively. This transformer is to be used as 13.2/12 kV step-down autotransformer in a power distribution system. What is the transformer’s series impedance in pu in the autotransformer connection? A. 0.0017 + j0.0058 C. 0.0020 + j0.0070 B. 0.0022 + j0.00778 D. 0.0018 + j0.0064 20. A transformers rated 500 kVA, 4800/480 V, 60 Hz when operated as a conventional two winding transformer is to be used as a 5.28/4.8 kV step down autotransformer in power distribution system. In the autotransformer connection, when is the transformer’s rating when used in this manner? A. 5MVA C. 5.5 MVA B. 6MVA D. 6.5 MVA 21. The open circuit and short circuit tests were performed on the primary side of the 25 kVA, 7620/240, 60 Hz transformer and the following data were obtained, open circuit test; Eoc = 7620 V, Ioc = 0.30 A and Poc = 500 W. Short circuit test Esc = 450 V, Isc = 3.5 A and Psc = 220 W. Determine the shunt and series impedances refer to the primary of the transformer. A. 116 + j26 k & 17.97 + j130 C. 112 + j22 k & 15.95 + j128 B. 124 + j14 k & 21.85 + j134 D. 120 + j10 k & 19.95 + j132 22. An induction motor is rated 240 V, 150 A and 0.707 power factor. What is the size of the capacitor in kVAR which must be place in parallel with the circuit to improve the power factor to 95% lagging? A. 17.1 C. 41.9 B. 24.3 D. 26.9 23. A transmission line cable consists of 26 strands of identical copper conductor, each 1.255 mm in diameter. The length of the cable is 10 km but because of the twist of the strands, the actual length of each conductor is increased by 5%. If the resistivity of the copper is 1.72 x 10-8 ohm-meter, what is the resistance of the cable in ohms? A. 1.08 C. 1.13 B. 5.39 D. 5.66 24. A single-phase transmission line 90 km is made up of hard drawn copper 500 mils in diameter. If the resistivity of the hard drawn copper at 20°C is 1.72 x 10-8 ohm-meter. Determine the loop resistance at 20°C. A. 0.1394 ohm/km C. 0.546 ohm/km B. 1.348 ohm/km D. 0,434 ohm/km 25. A three-phase transposed distribution line is designed with equilateral of 12 ft. it is decided to build the line with horizontal spacing D31=2D12=2D23. What should be the spacing between adjacent conductors in order to obtain the same inductance as the original design? A. 9. 5246 ft C. 9.5066 ft B. 9,6437 ft D. 9.6198 ft 26. A 69 kV three phase transposed line is composed of one ACSR 336,400 cmil, 36/7 Linnet conductor per phase with a horizontal configuration of D12=5 ft, D23= 5 ft and D23=10 ft. The conductors have diameter of 0.721 inch, resistance of 0.306 ohm per mile and gmr of 0.0244 ft. What is the reactance for 12 miles line. A. 6 ohms C. 4 ohms B. 2 ohms D. 8 ohms ELECTRICAL2/Page 3 Republic of the Philippines Professional Regulation Commission Board of Electrical Engineering Electrical Engineering Board Examination E2 8:00 am – 12:00 noon PROFESSIONAL ELECTRICAL ENGINEERING SUBJECTS SET A 27. A single circuit, transposed overhead transmission line is composed of twoconductors per phase. The diameter of each conductor is 5 cm. the distance between the center of the bundle is 5 m. What is the inductance per km per phase of the line. A. 0.4412 mH C. 0.9323 mH B. 0.9136 mH D. 0.8825 mH 28. A three-phase circuit, 60 Hz, 230 kV transposed transmission line is composed of two 1272 MCM, 54/19 conductors per phase with horizontal configuration. The bundle spacing is 50 cm while phase spacing between the centers of the bundle is 10 m. If the GMR of the ACSR conductors is 0.466 ft, find the inductive reactance in ohm/km/phase of the transmission line? A. 0.3775 C. 0.3628 B. 0.3398 D. 0.3964 29. A 115-kV three-phase transposed transmission line is composed of two ACSR 336,400 cmil, 36/7 Oricle conductors per phase with horizontal configuration:D12=7 ft; D23= 7 ft and D13= 14 ft. The line spacing as measured from the center of the bundled conductors is 6 inches. The conductors have a diameter of 0.741 inch a GMR of 0.02265 ft. Find the capacitance per phase for 20 km of the line in microfarads. A. 0.2889 C. 0.2300 B. 0.2609 D. 0.2719 30. A 75 kVA, 13.2 kV/240V delta-wye distribution transformer has a resistance of 1% pu and reactance of 8% pu. Wht is the transformer’s phase impedance referred to the high voltage side? A. 69.70 + j557.57ohms C. 71.09 + j558.72 ohms B. 69.95 + j543.63 ohms D. 70.58 + j564.54 ohms 31. The per phase parameters for a 60 Hz, 200 km long transmission line are R=2.07 Ω and L=310.8 mH and C=1.4774 μF. The transmission line supplies a 100 MW, wye connected load at 215 kV (line to line) and 0.9 power factor lagging. Using nominal π model, determine the sending end voltage line to line. A. 229 kV C. 236 kV B. 243 kV D. 233 kV 32. A generator of 50 MVA, 4 kV, X”d=25% and a transformer of 50 MVA, 4kV delta/115 kV wye-grounded operating on a 3.8 kV tap where Xt”=10% to be connected into a single equivalent reactance. What is the single equivalent reactance on a 100 MVA, 110-kV base? A. j0.7667 pu C. j0.8663 pu B. j0.6039 pu D. j0.8241 pu 33. The effect of the dielectric is to A. increase the capacitance C. decrease the capacitance B. increase the working voltage D. reduce the working voltage 34. What will happen to an insulating medium if subjected to a voltage more than its basic impulse insulation level? It will________. A. change its molecular structure C. become magnetic B. punctured D. melt 35. If the certain conductor has an area of 336,400 cmils, what is the radius of this conductor in cm? A. 0.663 C. 0.737 B. 0.8310 D. 0.921 ELECTRICAL2/Page 4 Republic of the Philippines Professional Regulation Commission Board of Electrical Engineering Electrical Engineering Board Examination E2 8:00 am – 12:00 noon PROFESSIONAL ELECTRICAL ENGINEERING SUBJECTS SET A 36. A 110V dc motor draws current of 30A and is located 500ft from the power source. What is the supply voltage if the diameter of the copper wire is 0.25 inch? Resistivity is 10.4 omhs-cmil per ft. A. 119 V C. 121 V B. 117 V D. 115 V 37. A series loop contains the following circuit elements in order a 8-volts source, a 2k ohms resistor, a 3k ohm resistor, a 16-V source and a 7k ohm resistor. What is the power absorbed by the 3k ohm resistor? A. 12 mW C. 0.12 W B. 1.2 mW D. 1.2 W 38. Three resistors 3, 4 and z ohms respectively are connected in parallel across a constant current source of 10A. Find the value of z if the resistor draws 3 A current. A. 6 ohms C. 4 ohms B. 2 ohms D. 8 ohms 39. The voltage applied across the resistor was reduced by 50%. The power consumed by resistor will reduced by? A. 75 C. 25 B. 50 D. 100 40. A 6 V car radio draws a current of 6.5 connected in series with it to operate A. 0.947 C. B. 0.969 D. A. What resistance in ohms must be it in a car with a 12 V battery? 0.923 0.981 41. Three resistors R1=9k ohm, R2=9k ohm and R3=9k ohm are connected in parallel across a 12-V power supply whose internal resistance is 1k ohm. How much current is drawn from the source? A. 6mA C. 2.4 mA B. 3mA D. 1.2 mA 42. A 20-ohm resistor is connected in parallel with a variable resistor R. The parallel combination is the connected in series with a 4-ohm resistor and connected across a 240V source. Determine the minimum value of R if the power of r is equal to the power taken by the 4-ohm resistor. A. 7.95 ohms C. 7.64 ohms B. 8.40 ohms D. 6.87 ohms 43. Two batteries are connected in parallel to feed a 12-ohm load. Battery A has open circuit emf of 6.3V and internal resistance of 1.5 ohms. Battery B has open circuit emf of 6V and an internal resistance of 2.1 ohms. What is the load current? A. 0.48 A C. 0.44 A B. 0.52 A D. 0.56 A 43. The resistance of a length of copper wire is 2.6 ohms at 20deg. C. The temp coefficient of resistance on a 20deg. C for copper is 0.0393. What is its resistance at 75deg. C? A. 3.670 ohms C. 11.38 ohms B. 3.162 ohms D. 4.378 ohms 44. A length of a copper telephone line has a resistance of 24 ohms at 20deg. C. What is the resistance on a hot summer day when its temp. raised to 36deg. C? A. 26.5 ohms C. 25.5 ohms B. 24.5 ohms D. 27.5 ohms ELECTRICAL2/Page 5 Republic of the Philippines Professional Regulation Commission Board of Electrical Engineering Electrical Engineering Board Examination PROFESSIONAL ELECTRICAL ENGINEERING SUBJECTS E2 8:00 am – 12:00 noon SET A 45. A certain copper wire has a resistance of 25 ohms at 10deg. C. Take the temp. coefficient at 10deg. C to be 0.00409deg/C. What must be the maximum operating temp.of the wire if its resistance is to increase by at most 20%? A. 58.89 C. 59.24 B. 60.13 D. 59.25 46. A 120 cm long conductor is carrying a current of 1.2 A and is situated at right angles to a field of flux density of 0.65T. Calculate the force on the conductor. A. 3.264 N C. 1.348 N B. 0.936 N D. 1.587 N 47. State the force in pounds upon one side of a coil of 50 turns carrying a current of 20 A if the real length of the coil is 12 inch and the flux density is 25,000 lines per square inch. There are 4.448x10^5 dynes in a pound. The conductors are at right angles to the flux. A. 29.4 C. 27.9 B. 25.3 D. 26.6 48. What is the complex expression for a given alternating current i=250 sin(wt + 25deg.)? A. 227 + j106 C. 227- j106 B. 160 - j75 D. 160+j75 49. The resistance of a length of copper wire is 2.6 ohms at 20˚C. The temperature coefficient of resistance at 20˚C for copper is 0.003939/˚C. What is its resistance at 75˚C. A. 3.670 ohms C. 11.38 ohms B. 3.162 ohms D. 4.378 ohms 50. Find the turn ratio of a transformer used to match a 14400 ohms load to a 400 ohms load. A. 5:1 C. 6:1 B. 4:1 D. 36:1 51. Two 2-H coil are connected in series so that the mutual induction between them is 0.2-H. find the total inductance when they are connected to be series aiding. A. 4.4 H C. 3.6 H B. 4 H D. 16 H 52. A poles lap wound, dc machine has 728 active conductors running at 1800 rpm. The flux per pole is 30 mWb. The armature current is 120A, what is the electromagnetic power developed in the armature in kW? A. 72.4 C. 65.5 B. 78.6 D. 62.4 53. When one coil of magnetically coupled pair has a current of 5 amperes, the resulting flux Φ11 = 0.4 mWb and flux Φ12 = 0.8 mWb respectively. If the turns are N1 = 500 and N2 = 1500, find the mutual inductance. A. 60 mH C. 120mH B. 80 mH D. 240 mH 54. The line currents in a delta connected load are Ia = 5 cis 0deg. Ib = 7.07 cis 225deg and Ic = 5 cis 90deg. Calculate the positive sequence components of current for phase a. A. 7.94 ∠224° C. 5.57 ∠-15° ELECTRICAL2/Page 6 Republic of the Philippines Professional Regulation Commission Board of Electrical Engineering Electrical Engineering Board Examination PROFESSIONAL ELECTRICAL ENGINEERING SUBJECTS B. 0 E2 8:00 am – 12:00 noon SET A D. 8.35 ∠-25° 55. Power system has receiving current of 1.2 pu or current at the receiving end and 0.6 pu voltage at the receiving end and 0.5 pu receiving power. When the base current is 160 A and base voltage is 20 kV, what is ohmic value of the resistance of the load? A. 68.725 C. 35.827 B. 57.765 D. 43.375 56. A resistance R and inductive reactance X are connected in parallel across 2.4 kV rms absorbs 288 kW at 0.8 power factor. Find the value of X in ohms. A. 20 C. 30 B. 26.67 D. 45 57. A 4 pole 60 Hz synchronous generator has a rating of 200 MVA, 0.8 power factor lagging. The moment inertia of the rotor is 45,100 kg-m2. Find inertia constant H. A. 3 MJ/MVA C. 4 MJ/MVA B. 5 MJ/MVA D. 6 MJ/MVA 58. A 250 MW, 60 Hz turbine generator has a speed regulation of 5% based on its own rating. The generator frequency decreases from 60 Hz to a steady state value of 59.7 Hz. Determined the increase in the turbine power output. A. 15 MW C. 20 MW B. 25 MW D. 30 MW 59. Two generating unit of 250 MW and 400 MW have governor speed regulation of 6% and 6.4% respectively from no-load to full load. They are operating in parallel and share a load of 500 MW. Determined the load shared by each unit. A. 200 MW & 300 MW C. 220 MW & 280 MW B. 225 MW & 275 MW D. 240 MW & 260 MW 60. The moment of inertia of a 100 MVA, 2 pole, 60Hz generator is 50x103 kg-m2. Determined the angular momentum M for the machine. A. 0.329 MJ rad/sec C. 0.569 MJ rad/sec B. 0.762 MJ rad/sec D. 0.432 MJ rad/sec 61. Two identical voltage source are 0.7+j2.4 ohm. V1 = 500 ∠16.26° volts delivered by source 1. A. 21 kW B. 34 kW connected by a line of impedance of and V2 = 585 ∠0° volts. Find the real power C. 28 kW D. 56 kW 62. A three phase transmission line is feeding from a 23/230-kV transformer at its sending end. The line is supplying a 150 MVA at 0.8 pf load through a step down transformer of 230/23 kV. The impedance of the line and transformers are 18+j60 ohms. The sending end transformer is energized at 23 kV. Determine the tap setting for each transformer to maintain voltage at the load at 23 kV. A. ts= 1.08 pu & tr= 0.926 pu C. ts= 0.926 pu & tr= 1.08 pu B. ts= 1.18 pu & tr= 0.916 pu D. ts= 1.12 pu & tr= 0.912 pu 63. A 100 kVA, 400 volts, wye connected salient pole synchronous generator runs at full load and 80% power factor leading. If Xd= 2Xq= 1.1 ohms per phase and Ra is negligible, calculate the voltage regulation. A. -26.4% C. -24.6% B. -64.2% D. -246% 64. A 400-V, 3-phase, wye-connected round-rotor synchronous motor operates at unity power factor while developing a power of 60 kW. If the synchronous ELECTRICAL2/Page 7 Republic of the Philippines Professional Regulation Commission Board of Electrical Engineering Electrical Engineering Board Examination E2 8:00 am – 12:00 noon PROFESSIONAL ELECTRICAL ENGINEERING SUBJECTS SET A reactance is 1 Ω per phase and the armature resistance is negligible, calculate the induced voltage per phase. A. 246.6 volts C. 231 volts B. 225.6 volts D. 254.3 volts 65. A two winding transformer rated 9 MVA, 120/90 volts, 60 Hz is to be connected as autotransformer to supply a load at 120 volts from 210 volts supply. What kVA load can be supplied without exceeding the current rating of the windings. A. 18 C. 21 B. 9 D. 24 66. A 60 MVA, 69.3-kV, three phase synchronous generator has a synchronous reactance of 15 ohms per phase and negligible armature resistance. The generator is delivering rate power at 80% power factor lagging at rated terminal voltage to an infinite busbar. If the generated emf is 36 kV per phase, what is the maximum three phase power that the generator can deliver before losing its synchronism? A. 288 MW C. 96 MW B. 320 MW D. 120 MW 67. A small wind generator is to be designed to generate 50 kW of power at a wind velocity of 25 mph. what is the approximate blade diameter? A. 26 ft C. 36 ft B. 42 ft D. 18 ft 68. A single 60 Hz power line and a telephone line are parallel to each other. The power line carries an rms current of 226 A. find the magnitude of voltage per Km induced in the telephone line. A. 8 V C. 3 V B. 6 V D. 5V 69. Calculate the positive sequence symmetrical components for the set of unbalance voltage Va= 300∠-120° , Vb= 200∠90° , and 100∠-30° A. 42.265 ∠-120°V C.193.185∠-135°V B. 86.947∠-120°V D. 185.567∠-120°V 70. The symmetrical components for the set of unbalance three phase currents are: Iao= 3∠-30°,Ia1= 5∠-90°,Ia2= 4∠30° find the current at line b A. 8.185∠42.216° C. 4∠-30° B. 8.185∠-102.216° D. 4 71. 72. Find the value of (1+a)/(1+a2) A. 1∠120° B. 3∠0° C. 3∠180° D. 1∠ − 120° What is the equivalent of Van1 1 A. 𝑉𝑏𝑐∠90˚ C. B. D. √3 1 𝑉𝑏𝑐∠120˚ √3 1 𝑉𝑏𝑐∠ − 90˚ √3 1 𝑉𝑏𝑐∠ − 120˚ √3 73. In the three phase system, phase is on no load, phase b and c are shorted – circuited to ground. The following current are given: Ib= 91.65∠160.9° and In=91.65∠160.9°. Find the zero sequence current. A. 20∠90° C. 40∠90° B. 60∠180° D. 30∠180° ELECTRICAL2/Page 8 Republic of the Philippines Professional Regulation Commission Board of Electrical Engineering Electrical Engineering Board Examination PROFESSIONAL ELECTRICAL ENGINEERING SUBJECTS E2 8:00 am – 12:00 noon SET A 74. A generator having a solid grounded neutral and rated 50 MVA, 30 kV has X1=25%, X2=15%, and Xo=5%. What reactance must be placed in the generator neutral to limit the fault currents for a bolted double line to ground fault to that for a bolted 3-phase fault? A. 2.4 ohms C. 0.825 ohm B. 1.8 ohms D. 0.765 ohm 75. A 4-pole, 60 Hz, 3-phase induction motor has a blocked rotor reactance of 0.5 ohm per phase and the rotor resistance of 0.1 ohm per phase. At what speed will the motor develop maximum torque? A. 1200 rpm C. 1440 rpm B. 1500 rpm D. 1620 rpm 76. A 10 Hp, 440 volts, 60 Hz, 3-phase, 6 pole, induction motor has 4% slip at full load. What is the full load speed? A. 1140 rpm C. 1152 rpm B. 1162 rpm D. 1200 rpm 77. A two winding transformer is rate 60 kVA, 240/1200 V, 60 Hz. When operated as a conventional two winding transformer at rated load, 0.8 pf lagging, its efficiency is 96%. This transformer is to be used as a 1440/1200 volts step down transformer, find the new efficiency at 0.8pf. A. 99.31% C. 98.9% B. 97.8% D. 96.8% 78. A 5 hp 4 pole, 60 Hz 3-phase induction motor with a wound rotor draws 4590 watts from the line. What is the speed of this motor when delivering 4.95 hp, if the core loss is 250 watts, the stator copper loss is 390 watts, and the friction and windage loss is 70 watts? A. 1720 rpm C. 1715 rpm B. 1724 rpm D. 1750 rpm 79. A 25 hp 240 volts series motor takes 93 amperes when driving its rated load at 800 rpm. The armature resistance is 0.12 ohm and the series field resistance is 0.08 ohm. At what speed will the motor operate if the load is partially removed so that the motor takes 31 ampere? Assume that the flux is reduced by 50% for a current drop 66 2/3 percent and that the brush drop is 2 volts at the both loads. A. 1690 rpm C. 1230 rpm B. 1580 rpm D. 1604 rpm 80. The power plant has a maximum demand of 100 MW and connected load of 160 MW. Annual generation of 500 GWH. Calculate the load factor. A. 32% C. 57% B. 37% D. 22% --------------------------------------------------------------------------------***This examination paper is a PROPERTY OF CERTC REVIEW CENTER. You MUST SUBMIT this paper together with your answer sheet once finished. DO NOT BRING THIS EXAMINATION PAPER OUTSIDE THE EXAMINATION ROOM. ELECTRICAL2/Page 9 Republic of the Philippines Professional Regulation Commission Board of Electrical Engineering Electrical Engineering Board Examination E2 8:00 am – 12:00 noon PROFESSIONAL ELECTRICAL ENGINEERING SUBJECTS SET A 81. The rated line current of a 230 volts shunt motor is 56 amp. If the field circuit resistance is 230 ohms and the armature circuit resistance is 0.15 ohms. What is the starting resistance to limit the current at starting to 125% of the full load armature current. A. 3.2 ohms C. 2.4 ohms B. 3.8 ohms D. 4.2 ohms 82. The voltage across 20 micro-farad capacitor varies vc=(10.75-1.5e-1000t) volts. What is the current through millisecond? A. 0.023 sec B. 0.013 sec with time as given by capacitor after 1 C. 0.011 sec D. 0.033 sec 83. A 100 hp, 1750 rpm, 2300 volts, 3-phase motor draws 150 amp when started at 2300 volts. If the compensator is to be used, and 80% voltage tap is selected, find the starting current. A. 96 A C. 120 A B. 108 A D. 75 A ELECTRICAL2/Page 10