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In the conventional dc machine (with a closed continuous commutator winding on its armature), for example, full-wave rectification of the alternating voltage induced in individual armature coils is achieved by means of a commutator, which makes a unidirectional voltage available to the external circuit through the stationary carbon brushes held against the commutator surface.The armaturewindings of dcmachines are located on the rotor because of this necessity for commutation and are of the closed continuous type, known as lap and wavewindings. The simplex lap winding has as many parallel paths as there are poles, whereas the simplex wave winding always has two parallel paths. The winding connected to the commutator, called the commutator winding, can be viewed as a pseudostationary winding because it produces a stationary flux when carrying a direct current, as a stationarywindingwould. The direction of the flux axis is determined by the position of the brushes. In a conventional dc machine, in fact, the flux axis corresponds to the brush axis (the line joining the two brushes). The brushes are located so that commutation (i.e., reversal of current in the commutated coil) occurs when the coil sides are in the neutral zone, midway between the field poles. The axis of the armature mmf is then in the quadrature axis, whereas the stator mmf acts in the field (or direct) axis. Figure shows schematic representations of a dc machine. The commutator is thus a device for changing the connections between a rotating closed winding and an external circuit at the instants when the individual coil-generated voltages reverse. In a dc machine, then, this arrangement enables a constant and unidirectional output voltage. The armature mmf axis is fixed in space because of the switching action of the commutator (even though the closed armature winding on the rotor is rotating), so the commutator winding becomes pseudostationary.
Explain the two types of materials that are formed after doping. Depending on the impurity added, extrinsic semiconductors can be then subdivided in two types of class: N-ty
Q. These data were obtained from tests carried out on a 10-kVA, 2300:230-V, 60-Hz distribution transformer: • Open-circuit test, with low-voltage winding excited: applied voltag
Design a recycling MOD 19 up counter using JK FFs. In your design, include the logic circuit diagram and the timing diagram output that counts from 000002 = 010 to 100112 = 1910. C
Merits: 1. It is very simple to shift the operating point anywhere in the active region by just changing the base resistor (R B ). 2. A very small number of compon
What are the 8086 interrupt types? Dedicated interrupts Type 0: Divide by zero interrupt Type 1: Single step interrupt Type 2:Non maskable interrupt Type 3: Breakpo
Machine Control Instructions Instructions used to control various machine operations are kept in this group.
Q. Illustrate about Transfer Functions? The transfer function is a means by which the dynamic characteristics of devices or systems are described. The transfer function is a ma
Q. What do you mean by FM Stereo? IT shows the block diagram of an FM stereo transmitter and an FM stereo receiver. The following notation is used: • f L (t), fR(t): Left a
principle and operation of 3phace induction motor
A moving coil galvanometer consists of a coil in a uniform magnetic field B o, suspended fro a fibre of torque constant C, current I produces a deflection O=nAB o i/c where n is
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