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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.
Q. (a) Consider the capacitor - input filter circuit of Figure and obtain the z-parameters for the circuit. (b) Determine the transfer function V 2 /V 1 when I 2 is zero.
Financing the power sector projects: Massive investment is required for the targeted expansion of the sector. It has been estimated at Rs. 9 lakh crores in the further 10 yea
Consider the circuit shown in Figure in the t -domain as well as in the s-domain. Formulate the s-domain nodal equations and use MATLAB to solve for V A (s) and V B (s).
analysis and detail working of bootstrap sweep circuit
Explain the Johnson Counters? The Johnson counters are a variation of standard ring counters with the inverted output of the last stage fed back to the input of the first stage
what is the difference between half &full wave rectifier
Q. A balanced three-phase, wye-connected, 2400- V, 60-Hz source supplies two balanced wye- connected loads in parallel. The first draws 15 kVA at 0.8 power factor lagging, and the
Power in Balanced Three-Phase Circuits The total power delivered by a three-phase source, or consumed by a three-phase load, is found simply by adding the power in each of the
dis advantage of series clippers?
The LEDs should also show the rounded percentage of the full scale output. Since there are 8 LEDs every one represents 12.5%. Though, since we want the rounded percentage the LED o
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