Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
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.
A cylindrical shell with flat ends is of 1.5 m Internal diameter and 4 m length. It is subjected to an internal pressure of 300 N/cm 2 . The principal stress is not to exceed 15 K
In a CDMA system, the signal is spread over a large bandwidth by multiplying the transmitted symbol by a sequence of short pulses, also called chips. The
Q. What is Pinch - off voltage? The reverse bias is relatively large near the source. As a result, the depletion region intrudes into the channel near the drain, and the effec
State and explain three factors upon which the induced electromotive force depends
What do you understand by DB assembler directive? DB (Define Byte): The DB directive explains by a byte-type variable (that is a variable that occupies one byte of memo
what is a transformer?
Write an m-file "sampling.m", which will take as an input: a signal and a sampling step and will display the sampled signal and the magnitude of its Fourier transform. sampling
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. Consider an amplifier as a voltage source with an internal resistance of 72 . Find the turns ratio of the ideal transformer such that maximum power is delivered when the amplif
Q. Write notes on clamping ? Clamping network shifts (clamps) a signal to a different d.c level, that is it introduces a d.c. level to an a.c signal. Hence, the clamping networ
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd