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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.
DI Disable Interrupts Instruction The interrupt enable flip flop is reset and all the interrupts of 8085 microprocessors except TRAP are disabled . the instruction form
Q. For a part of the network shown in Figure, given that i 1 = 4A; i 3 (t) = 5e -t , and i 4 (t) = 10 cos 2t, find v 1 , v 2 , v 3 , v 4 , i 2 , and i 5 .
In practice, it is usually better to wind the field coils on the rotor and supply the field current to them via slip rings. As the rotor turns, the changing magnetic field expe
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Determine the self inductance of the two coils: Two coils with a coefficient of coupling of 0.6 between them are connected in series so as to magnetize (i) in the same directi
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
Explain index mode and base address mode (with examples) available in microprocessors. Index Mode and Base Address Mode: Address supplied through the instruction is adde
Consider a transmitter S which radiates a sinusoidal carrier frequency of 1850 MHz. For a vehicle moving at 26.82 m/s, compute the received carrier frequency if the vehicle is movi
Q. Let m 1 (t) and m 2 (t) be two message signals, and let u 1 (t) and u 2 (t) be the corresponding modulated versions. (a) When the combined message signal m 1 (t) + m 2 (t) DS
Q. Write notes on clamping ? When a signal drives an open-ended capacitor the average voltage level on the output terminal of the capacitor is determined by the initial charge
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