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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.
Q. The armature of 6 -pole dc generator has a wave winding containing 664 conductors. Calculate the generator emf when flux per pole is 0.06 weber and the speed is 250 rpm. At wh
1. Write the Boolean expression and draw the gate logic diagram and typical PLC ladder logic diagram for a control system wherein a fan is to run only when all of the following con
For Sign Flag CP ( Call on plus ) CM (Call on minus ) Instruction CP call the subroutine from the specified memory location if sign flag is not set or reset( S=0)
when i/p voltg is grater than battery diode is clse or open
Distinguish between paramagnetic and diamagnetic materials, mentioning at least one example of each. Paramagnetic Materials: The atoms of these materials have permanent magne
Mode1 When the positive pulse from PWM is applied to the transistor Q shown in figure it gets turned on. In this condition current flows through transistor Q and.
Explain instruction sets of 8085. a) Data transfer group - MOV, MVI, LXI. b) Arithmetic group - ADD, SUB, INR. c) Branch group - JMP, JNZ, CALL. d) Logical group -
Q. An op amp has an open-loop frequency response as shown in Figure. (a) Find the approximate bandwidth of the circuit using this op amp: (i) With a closed-loop voltage gain
Describe the uses of GPS map This is far safer because a driver of a vehicle doesn't have to consult maps while driving. It also removes error (for example going the wrong way
Common Drain Amplifier In electronics, a common-drain amplifier, as well termed as a source follower, is one type of three basic single-stage field effect transistor (FET) am
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