The plunger of a solenoid is connected to a spring. The plunger of a solenoid is connected to a spring. The spring force is given by f = K0 (0.9a â x), where x is the air-gap length. The inductance of the solenoid is of the form L = L0 (1 â x/a), and its […]
The phase windings of the castleated machine of Figure are The phase windings of the castleated machine of Figure are to be excited by turning the phases on and off individually (i.e., only one phase can be on at any given time). a. Describe the sequence of phase excitations required to move the rotor to […]
The permanent magnet motor of Problem 11.17 is to be The permanent magnet motor of Problem 11.17 is to be operated under vector control using the following algorithm. Terminal voltage not to exceed rated value, Terminal current not to exceed rated value iD = 0 unless flux weakening is required to avoid excessive armature voltage. […]
The nameplate on a 7.97-kV: 460-V, 75-kVA, single-phase The nameplate on a 7.97-kV: 460-V, 75-kVA, single-phase transformer indicates that it has a series reactance of 12 percent (0.12 per unit). a. Calculate the series reactance in ohms as referred to (i) the low-voltage terminal and (ii) the high-voltage terminal. b. If three of these transformers […]
The open-circuit terminal voltage of a three-phase, 60-Hz synchr The open-circuit terminal voltage of a three-phase, 60-Hz synchronous generator is found to be 15.4 kV rms line-to-line when the field current is 420 A. a. Calculate the stator-to-rotor mutual inductance Laf. b. Calculate the open-circuit terminal voltage if the field current is held constant while […]
The object of this problem is to illustrate how the The object of this problem is to illustrate how the armature windings of certain machines, i.e., dc machines, can be approximately represented by uniform current sheets, the degree of correspondence growing better as the winding is distributed in a greater number of slots around the […]
A system such at that shown in Figure is used A system such at that shown in Figure is used to convert balanced 50-Hz voltages to other frequencies. The synchronous motor has four poles and drives the interconnected shaft in the clockwise direction. The induction machine has six poles and its stator windings are connected […]
A three-phase diode bridge is supplied by a three-phase A three-phase diode bridge is supplied by a three-phase autotransformer such that the line-to line input voltage to the bridge can be varied from zero to 230 V. The output of the bridge is connected to the shunt field winding of a dc motor. The resistance […]
A three-phase generator step-up transformer is rated 26-kV: 345- A three-phase generator step-up transformer is rated 26-kV: 345-kV, 850 MVA and has a series impedance of 0.0035 + j0.087 per unit on this base. It is connected to a 26-kV, 800-MVA generator, which can be represented as a voltage source in series with a reactance […]
Repeat Problem 2.11 for a 75-kVA, 60-Hz, 4600-V: 240-V Repeat Problem 2.11 for a 75-kVA, 60-Hz, 4600-V: 240-V distribution transformer whose resistances and leakage reactanceâs are R1 = 0.846 ? R2 = 0.00261 ? X11 = 26.8 ? X12 = 0.0745 ? where subscript 1 denotes the 4600-V winding and subscript 2 denotes the 240-V […]