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

Determine and sketch il for inductance, Q. For the circuit of Figure, deter...

Q. For the circuit of Figure, determine and sketch i L (t) and vC(t) for inductance values of (a)3/4 H, (b) 2/3 H, and (c) 3/17 H. Note that the inductance values are chosen her

Interrupts, how the interrupts are affected by system rest

how the interrupts are affected by system rest

Electrical machine, Explain the principle of induction applied in electrica...

Explain the principle of induction applied in electrical machine

Reflection and retraction in cables and their calculations, How do I calcul...

How do I calculate the line-cable and cable-line values of reflection and refraction coordinates?

Electromagnetic Computational (MATLAB), Hey Dear i have a hw in MATLAB by a...

Hey Dear i have a hw in MATLAB by applying Finite Element Method there(Electromagnetic) and i need your help with it. please take alook at the question and let me know if you can h

Explain workinf of colpitts oscillator, Q. Explain workinf of colpitts osci...

Q. Explain workinf of colpitts oscillator? When the collector supply voltage V cc is switched on, the capacitors C1 and Cz are charged. These capacitors C1 and Cz discharge thr

Bivector meter, Bivector Meter As it is clear from the name provided '...

Bivector Meter As it is clear from the name provided 'Bivector', it records kWh and kVAh consumption along with maximum demand on both or on any one as needed. The working pri

Information processing, Information Processing: Information processin...

Information Processing: Information processing is the key to improving cutting and productivity costs of excess work. Converting information to a computerized format in GIS i

Define time and shift invariant, Define Time and Shift Invariant? Time ...

Define Time and Shift Invariant? Time and shift invariant means that the system characteristics and shift do not change with time, i.e. the system output is independent of the

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