Stray leakage fields will induce rotor-frequency voltages in a p The nameplate on a 460-V, 50-hp, 60-Hz, four-pole induction motor indicates that its speed at rated load is 1755 r/min. Assume the motor to be operating at rated load. a. What is the slip of the rotor? b. What is the frequency of the rotor […]
Ro = 4.0 cm h = 2cm g = 0.2 cm Calculate: a. the b. Repeat the calculation of part (a) for the case in which the core and plunger are composed of a nonlinea .A three-phase Y-? transformer is rated 225-kV: 24-kV, 400 MVA and has a series reactance of 11.7 ? as referred […]
Ro = 4.0 cm h = 2cm g = 0.2 cm Calculate: a. the b. Repeat the calculation of part (a) for the case in which the core and plunger are composed of a nonlinear material whose permeability is given by where Bm is the magnetic flux density in the material. c. For the nonlinear […]
Replace the 28-tooth rotor of Problem 8.7 with a rotor Replace the 28-tooth rotor of Problem 8.7 with a rotor with 26 teeth. a. Phase 1 is excited, and the rotor is allowed to come to rest. If the excitation on phase 1 is removed and excitation is applied to phase 2, calculate the resultant […]
Repeat Problem 7.6 including the saturation effects represented Repeat Problem 7.6 including the saturation effects represented by the saturation curve of Figure. For part (a), set the field current equal to the value required to produce an open-circuit armature terminal voltage of 250 V at 1200r/min.
A three-phase, variable-speed induction motor is operated from a A three-phase, variable-speed induction motor is operated from a variable frequency, variable-voltage source which is controlled to maintain constant peak air-gap flux density as the frequency of the applied voltage is varied. The motor is to be operated at constant slip frequency while the motor speed […]
A three-phase, Y-connected, 460-V (line-line), 25-kW, 60-Hz, A three-phase, Y-connected, 460-V (line-line), 25-kW, 60-Hz, four-pole induction motor has the following equivalent-circuit parameters in ohms per phase referred to the stator: R1 = 0.103 R2 = 0.225 X1 = 1.10 X2 = 1.13 Xm = 59.4. The total friction and wind age losses may be assumed […]
A three-phase, eight-pole, 60-Hz, 4160-V, 1250-kW squirrel-cage A three-phase, eight-pole, 60-Hz, 4160-V, 1250-kW squirrel-cage induction motor has the following equivalent-circuit parameters in ohms-per-phase-Y referred to the stator: R1 = 0.212 R2 = 0.348 X1 = 1.87 X2 = 2.27 Xm = 44.6. It is operating from a field-oriented drive system at a speed of 805r/min […]
A three-phase Y-connected ac machine is initially operating A three-phase Y-connected ac machine is initially operating under balanced three-phase conditions when one of the phase windings becomes open-circuited. Because there is no neutral connection on the winding, this requires that the currents in the remaining two windings become equal and opposite. Under this condition, calculate […]
A three-phase two-pole winding is excited by balanced three A three-phase two-pole winding is excited by balanced three-phase 60-Hz currents as described by Eqs. 4.23 to 4.25. Although the winding distribution has been designed to minimize harmonics, there remains some third and fifth spatial harmonics. Thus the phase-a mmf can be written as Fa = […]