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

Use of monitoring and control in nuclear and chemical plants, Use of Monito...

Use of Monitoring and control in nuclear and chemical plants In nuclear and chemical plants, there is generally a combination of control and monitoring taking place. Informatio

Transistor, can you differentiate the alpha,beta and gamma

can you differentiate the alpha,beta and gamma

Find the total emf and armature current., Q.   In a 110V compound generator...

Q.   In a 110V compound generator, the armature, shunt and series winding resistance are 0.06?, 25? and 0.04? respectively. The load consists of 200 lamps each rated 55W, 110V conn

Explain the time division space switching, a. Explain the time division spa...

a. Explain the time division space switching b. Verify the execution complexity of 2048 channel TST switch with 16 TDM links and 128 channels. Let the time slot of space switch

Chemistry, write a short note on Scale

write a short note on Scale

Determine the circuit of three transistors dynamic ram cell, a. Determine t...

a. Determine the circuit of three transistors dynamic RAM cell and define briefly read and write functions. b. Write short note on factors influencing choice of layer for wiring

Describe the design procedure of oai 321 cell at transistor, Obtain express...

Obtain expressions for the drain source current in an n-channel MOS transistor in terms of terminal voltages and transistor parameters. Indicate reasons why, for deep sub micron t

What is the voltage gain of common gate amplifier, Q. What is the voltage g...

Q. What is the voltage gain of common gate amplifier? The controlled source gmVgs is connected from drain to source with rd in parallel.The resistor is connected Rs is connecte

Design a multiplexer and anomalous signals, 1. The size of the multiplexer ...

1. The size of the multiplexer used to implement a truth table can be cut in half (e.g. 4 inputs instead of 8) if one of the variables is used as an input instead of being connecte

Check Sheets - Quality Tools for Improvement, Check Sheets - Quality Tools ...

Check Sheets - Quality Tools for Improvement This might be an easy listing of items that could represent information in an efficient, graphical format. If the system under ana

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