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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.
Immediate Addressing In this addressing mode that 8/16 bit data is specified in the instruction itself as its one of the operands. Normally the instructions using a
#question what are the types of lines used there and their application ..
Q. What do you mean by Companding? In order to lower the crest factor of a waveform, so as to produce better performance, a process known as companding is used. It works like a
HOW DOES SINGLE PHASE INDUCTION MOTORS DEVELOP A STARTING TORQUE ?
Q. A sectional view of a cylindrical iron-clad plunger magnet is shown in figure. The small air gap between the sides of the plunger and the iron shell is uniform and 0.25 mm long.
Forward bias In forward bias, the p-type is linked with the positive terminal and the n-type is linked with the negative terminal.In forward bias mode the PN junction operati
Program Description In the above program any two numbers can be stored in register A and B ( by replacing XX and YY). Contents of B are compared with A. If B CY = 0
a rectangular surge of 2us duration and magnitude of 100Kv travels along a line of surge impedance 500 ohms. The latter is connected to another line of equal impedance through an i
Capacitors : These are electrical condensers having a system of electrical conductors and insulators. The simplest form consists of two parallel metal plates separated by a layer
Structure and use of PNP transistor: The figure opposite is a schematic presentation of a PNP transistor related to two voltage sources. To construct the transistor conduct ap
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