Dc machine, Electrical Engineering

Assignment Help:

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.

876_dc machine.png


Related Discussions:- Dc machine

Emirrer feedback bias, RE should be made large enough to swamp out rB/ B. h...

RE should be made large enough to swamp out rB/ B. how does making RE large saturate the transistor b

Define the term paging unit, Define the term Paging Unit. Paging Unit:...

Define the term Paging Unit. Paging Unit: The paging mechanism functions along with 4K - byte memory pages or along with a new extension obtainable to the Pentium with 4M byt

Microgrid, how to connect some DG together?

how to connect some DG together?

With the help of the structures explain lcd, Q. With the help of the struct...

Q. With the help of the structures explain LCD. A liquid crystal display (LCD) is a thin, flat display device made up of any number of color or monochrome pixels arrayed in fro

Autotransformer, conversion of auto transformer in to winding transformer a...

conversion of auto transformer in to winding transformer and vice versa

Dcr decrement instruction , DCR  Decrement Instruction This instructi...

DCR  Decrement Instruction This instruction  is used to decrement  the contents of any  register or memory  location by one. There are two  formats.

Illustrates power dissipation management in embedded system, Illustrates ab...

Illustrates about the power dissipation management in embedded system? Power Dissipation Management a. Clever real-time programming through Wait and Stop instructions b.

Grid connected hybrid pv-wind power system, Hi there, My project title is g...

Hi there, My project title is grid connected hybrid pv-wind power system. For this topic, i need a specification of the system. For this system a matlab and homer software simulati

Write the volt-ampere relations for the coupled inductors, Q. For the coupl...

Q. For the coupled inductors shown in Figure, neglecting the coil resistances, write the volt-ampere relations.

Show schematic arrangement of one- dimensional addressing, Q. Show the sche...

Q. Show the schematic arrangement for: (a) one- dimensional addressing, and (b) two-dimensional addressing, if a 32-kbit ROM is used to provide an 8-bit output word.

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

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!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd