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.
Calculate the cross-sectional area, in mm 2 , of a piece of aluminium wire 100 m long and having a resistance of 2Ω. Take the resistivity of aluminium as 0.03 x 10-6 Ωm.
Q. What are the different types and uses of delay line in CRO? OR Why is a delay line used in the vertical section of the oscilloscope? Sol. All electronic circui
Core Functionalities of the GIS: The GIS should be able to: 1 Create layers from all supported data sources involving coverage feature classes, shape files, compu
Explain the construction of a MOSFET. Draw the symbols and diagrams of both P-channel and N-channel MOSFET. As JFET and MOSFET also have source, drain and gate. Its gate is ins
A 3-kVA, 220:110-V, 60-Hz, single-phase transformer yields these test data: • Open-circuit test: 200 V, 1.4 A, 50 W • Short-circuit test: 4.5 V, 13.64 A, 30 W Determine th
The property due to which the resistance of some metal or compound vanishes under certain conditions is (A) Semi conductivity. (B) Super conductivity.
For the network shown in Figure, find the current in each resistor by means of nodal analysis.
If a second current carrying conductor is placed near to the first and the corresponding magnetic fields drawn, we can begin to visualise why a force is created between them. If
GAS HAZARDS IN THE LABORATORY : As mentioned in the introduction of this unit, the gas hazards in a laboratory arise from LPG and other compressed gases. Though the use of gas for
Q. How is the electron beam focused to a fine spot on the face of the CRT? Sol. The functional diagram of an electrostatic focusing arrangement is shown below. The pre-accele
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