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

Find the current in each resistor, For the network shown in Figure, find th...

For the network shown in Figure, find the current in each resistor by means of nodal analysis.

What are the various tones used in stronger telephony, Q. What are the vari...

Q. What are the various tones used in stronger telephony? When called party line is obtained, exchange control equipment transmits out the ringing current to telephone set of t

Power supply and clock frequency - pins and signals , Power Supply  and C...

Power Supply  and Clock Frequency there are following  pins  for power  supply  and clock  frequency  signals. V CC + 5 V  power supply. V SS Ground reference X 1

Determine the parameters of the equivalent circuit, No-load and blocked-rot...

No-load and blocked-rotor tests are conducted on a three-phase,wye-connected inductionmotor with the following results. The line-to-line voltage, line current, and total input powe

Dc motors, i dont understand why equalizer connection is not used in wave w...

i dont understand why equalizer connection is not used in wave windings?

Theft or pilferage of power by the existing customers, Theft or Pilferage o...

Theft or Pilferage of Power by the Existing Customers Power theft through the existing consumers is the predominant cause of loss of revenue to the electrical utilities. Almos

Dc generator, Why dummy coil is used in wave winding porpose of dc generato...

Why dummy coil is used in wave winding porpose of dc generator

Zener diode, Zener Diode A Zener diode is a sort of diode that allows ...

Zener Diode A Zener diode is a sort of diode that allows current not only in the forward direction such as a normal diode, but as well in the reverse direction if the voltage

Sonic harassment, Sir I would like to find a sensor that can detect beams ...

Sir I would like to find a sensor that can detect beams from the phasor painfield generator and the sonic devasator (devices of this nature). These sonic devices emit a high pres

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