Figure shows a circularly symmetric system in which a moveable Figure shows a circularly symmetric system in which a moveable plunger (constrained to move only in the vertical direction) is supported by a spring of spring constant K = 5.28 N/m. The system is excited by a samarium-cobalt permanent-magnet in the shape of a washer […]
Design calculations show the following parameters for a three-ph Design calculations show the following parameters for a three-phase, cylindrical-rotor synchronous generator: Phase-a self-inductance Laa = 4.83mH. Armature leakage inductance Lal = 0.33mH. Calculate the phase-phase mutual inductance and the machine synchronous inductance.
The following data are obtained from tests on a 145-MVA, The following data are obtained from tests on a 145-MVA, 13.8-kV, three phase, 60-Hz, 72-pole hydroelectric generator. Open-circuit characteristic: Short-circuit test: If = 710 A, Ia = 6070 A a. Draw (or plot using MATLAB) the open-circuit saturation curve, the air-gap line, and the short-circuit […]
Draw the steady-state, direct- and quadrature-axis phasor Draw the steady-state, direct- and quadrature-axis phasor diagram for a salient-pole synchronous motor with reactances Xd and Xq and armature resistance Ra. From this phasor diagram, show that the torque angle d between the generated voltage Eaf (which lies along the quadrature axis) and the terminal voltage Vt […]
The coils of the magnetic circuit shown in figure are The coils of the magnetic circuit shown in figure are connected in series so that the mmf’s of paths A and B both tend to set up flux in the center leg C in the same direction. The coils are wound with equal turns, N1 […]
Describe the effect on the torque-speed characteristic of an ind Describe the effect on the torque-speed characteristic of an induction motor produced by (a) Halving the applied voltage and (b) Halving both the applied voltage and the frequency. Sketch the resultant torque-speed curves relative to that of rated-voltage and rated-frequency. Neglect the effects of stator […]
The dc motor of Problem 11.1 has a field-winding inductance The dc motor of Problem 11.1 has a field-winding inductance Lf = 3.7 H and a moment of inertia J = 0.081 kg 路 m2. The motor is operating at rated terminal voltage and an initial speed of 1300 r/min. a. Calculate the initial field […]
The following data apply to a 125-kW, 2300-V, three-phase The following data apply to a 125-kW, 2300-V, three-phase, four pole, 60-Hz squirrel-cage induction motor: Stator-resistance between phase terminals = 2.23 O. No-load test at rated frequency and voltage: Line current = 7.7 A Three-phase power = 2870 W. Blocked-rotor test at 15 Hz: Line voltage […]
The data sheet for a small permanent-magnet dc motor provides The data sheet for a small permanent-magnet dc motor provides the following parameters” Rated voltage: Vrated = 3 V, Rated output power: Prated = 0.28 W, No-load speed: nnl = 12,400 r/min, Torque constant: Km = 0.218 mV/(r/min), Stall torque: Tstall = 0.094 oz 路 […]
The dc motor of Problem 7.25 will be used to The dc motor of Problem 7.25 will be used to drive a load which requires a power of 0.75 W at a speed of 8750 r/min. Calculate the armature voltage which must be applied to achieve this operating condition.