Consider a multi-stack, multiphase variable-reluctance stepping Consider a multi-stack, multiphase variable-reluctance stepping motor, such as that shown schematically in Figure, with 14 poles on each of the rotor and stator stacks and three stacks with one phase winding per stack. The motor is built such that the stator poles of each stack are aligned. a. […]
Consider a dc shunt motor connected to a constant-voltage source Consider a dc shunt motor connected to a constant-voltage source and driving a load requiring constant electromagnetic torque. Show that if Ea > 0.5Vt (the normal situation), increasing the resultant air-gap flux decreases the speed, whereas if Ea < 0.5vt=”” (as=”” might=”” be=”” brought=”” about=”” […]
Assume the total load in the system of Problem 2.26 Assume the total load in the system of Problem 2.26 to remain constant at 325 MVA. Write a MATLAB script to plot the line-to-line voltage which must be applied to the sending end of the feeder to maintain the load voltage at 24 kV line-to-lines […]
A loudspeaker is made of a magnetic core of infinite A loudspeaker is made of a magnetic core of infinite permeability and circular symmetry, as shown in figures a and b. The air-gap length g is much less than the radius r0 of the central core. The voice coil is constrained to move only in […]
Consider a two-phase stepper motor with a permanent-magnet rotor Consider a two-phase stepper motor with a permanent-magnet rotor such as shown in Figure and whose torque-angle curve is as shown in Figure a. This machine is to be excited by a four-bit digital sequence corresponding to the following winding excitation: a. Make a table of […]
The nameplate on a 50-MVA, 60-Hz single-phase transformer The nameplate on a 50-MVA, 60-Hz single-phase transformer indicates that it has a voltage rating of 8.0-kV: 78-kV. An open-circuit test is conducted from the low-voltage side, and the corresponding instrument readings are 8.0kV, 62.1A, and 206kW. Similarly, a short-circuit test from the low-voltage side gives readings […]
Consider the case in which the load on the synchronous Consider the case in which the load on the synchronous motor in the field oriented torque-control system of Problem 11.13 is increased, and the motor begins to slow down. Based upon some knowledge of the load characteristic, it is determined that it will be necessary […]
The motor of Problem 5.5 is supplied from a 460-V, three-phase The motor of Problem 5.5 is supplied from a 460-V, three-phase source through a feeder whose impedance is Zf = 0.084 + j0.82?. Assuming the system (as measured at the source) to be operating at an input power of 40 kW, calculate the magnitude […]
The magnetic circuit of Problem 1.1 has a nonlinear core The magnetic circuit of Problem 1.1 has a nonlinear core material whose permeability as a function of Bm is given by where Bm is the material flux density. a. Using MATLAB, plot a dc magnetization curve for this material (Bm vs. Hm) over the range […]
The magnetic circuit of figure has two windings and two The magnetic circuit of figure has two windings and two air gaps. The core can be assumed to be of infinite permeability. The core dimensions are indicated in the figure. a. Assuming coil 1 to be carrying a current Il and the current in coil […]