Electric Machinery Fundamentals
Session 2017 (B & D)---- Quiz 5
Electrical Engineering Department UET Lahore
Time: 40 minutes
Maximum Marks = 20
Q-1 Two identical 600-kVA. 480-V synchronous generators are connected in parallel to supply a
load. The prime movers of the two generators happen to have different speed droop characteristics.
When the field currents of the two generators are equal.one delivers 400 A at 0.9 PF lagging, while
the other delivers 300A at 0.72 PF lagging.
(a) What are the real power and the reactive power supplied by each generator to the load?
(b) What is the overall power factor of the load?
(c) In what direction must the field current on each generator be adjusted in order for them to operate
at the same power factor? (2+1+3)
Q-2 A three-phase, two-pole, 60-Hz induction motor is observed to be operating at a speed of
3502 r/min with an input power of 15.7 kW and a terminal current of 22.6 A. The stator winding
resistance is 0.20 Ω/phase. Calculate the 12 R power dissipated in rotor. (3)
Q-3: The following test data were taken on a 7.5-hp,
four-pole, 208-V, 60-Hz, design A, Y-connected
induction motor having a rated current of 28 A. (11)
(a) Sketch the per-phase equivalent circuit for this
motor.
(b) Find the slip at the pullout torque, and find the
value of the pullout torque itself.
Electric Machinery Fundamentals
Session 2017 (B & D)---- Quiz 5
Electrical Engineering Department UET Lahore