A 30 hp, three-phase, wye connected, 60 Hz, 360 V, synchronous motor is operating at 50% full load, rated voltage and 0.8 pf leading. The motor has negligible armature resistance and a synchronous reactance of 2.5 W /phase. Stator core loss is 1kW and friction and windage loss is 1.5 kW. Use this information to answer question What is the reactive power exported to the grid when the motor load is 30 hp the line-to-neutral excitation voltage is 255 V? and A. 4.71 kVar B. 6.69 kVar C. 6.99 kVar D. 7.41 kVar E. 9.66 kVar

3.An induction motor has a rotor resistance and reactance at standstill of 0.1 ohm and 3.5 ohm respectively. At standstill the voltage induced to the rotor is 60volts per phase. If the slip is 5%, determine the rotor current

A 220 V, 50 Hz, 4-Pole, 1410 rpm, single phase induction motor has the following parameters: R₁ = 9.5 Q, X₁ = 12 Q, R₂ = 10.8 Q, X2 = 12 2, and XM = 260 Q. At rated speed the core loss is 30W, and the friction and windage loss is 15W. The motor is connected to a single phase 220V, 50 Hz and runs at the rated speed. Determine: the slip, motor current, power factor, input power, developed torque, output shaft power, shaft torque, efficiency, rotor frequencies, rotor copper losses, and the ratio of forward flux to the backward flux.

A 2300-V, 3-phase, wye - connected, round rotor synchronous motor has a synchronous reactance of 3 ohms per phase and an armature resistance of0.25 ohm per phase. The motor operates on load such that the power angle is -15 degrees, and the excitation is so adjusted that the internally induced voltage is equal to the magnitude of the terminal voltage. Determine the armature current.

Q2] Fill in the blank (9 Marks) 1-The current drwan by the armature of D.C. motor is directly proportional to 2- The speed of a D.C. shunt-wound motor will shunt field regulator is increased. 3- The synchronous speed of a three-phase induction motor is number of pairs of poles. Rotor copper losses Rotor input power in induction motor = 5- A 4-pole three-phase induction motor has a synchronous speed of 25 r.p.s. The frequency of the supply to the stator is_ Hz. 6- The power input to a mains transformer is 200VA. If the primary current is 2.5A, the secondary voltage is 2V and assuming no losses in the transformer, the turns ratio step down. is 7- A 200kVA transformer has an iron loss of 1 kW and full load cu loss of 2 kW. Its load kVA corresponding to maximum efficiency is kVA. 8- If cu loss of a transformer at 7/8th full load is 4900 W, then its full-load cu loss would be watt. 4- if the value of resistance of the proportional to the 9- The slight curvature at the lower end of the open…

A three –phase, 440V, 50 Hz, 6 – pole induction motor running at 950 rpm takes 50 kW at certain load. The friction and windage loss is 1.5 kW and the stator losses = 1.2 kW. Determine the output from the rotor. (a). 42.68 kW                 (b). 46.48 kW (c). 48.80 kW                 (d). 44. 86 kW

2.. A three-phase 60 Hz asynchronous motor runs at 890 rpm at idle and 840 rpm at full load. ww w w www wwww a) How many poles does this motor have? b) What will be thę slip at nominal load? c) What happens if the nominal load is slipping at half? www. d) What is the electrical frequency of the rotor at half the nominal load? wwww

A 208-V, 50-Hz, 12-pole, Y-connected, three-phase induction motor has a stator impedance of 0.1 + j0.3 W phase and a rotor impedance of 0.06 + j0.8 R/phase at standstill. The core-loss resistance is 150 R/phase, and the magnetization reactance is 750 W phase. The friction and windage loss is 2 kW. When the motor operates at its full-load slip of 5%, determine (a) the power input, (b) the stator copper loss, (c) the rotor copper loss, (d) the air-gap power, (e) the power developed, (f) the power output, (g) the effi- ciency, (h) the shaft torque, and (i) the horsepower rating of the motor.

A 440-V, 60-Hz, 2-pole, Y-connected, three-phase induction motor has the following parameters in ohms/phase: R1 = 0.3, X1 = 0.9, R2 = 0.6, X2 = 0.9, Rc = 150, Xm = 60. If the rotational loss is 4% of the powerdeveloped, determine the efficiency of the motor when it runs at 4% slip.

A 3 phase, 1500 rpm, 2200 V, star connected synchronous motor has an impedance of 0.4+j90 per phase. At some excitation 2900 V is induced in the armature. Find the maximum torque developed by motor before the motor breaks out of synchronism. Also find the load angle this time.