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When a machine has more than two poles, only a single pair of poles needs to be considered because the electric, magnetic, and mechanical conditions associated with every other pole pair are repetitions of those for the pole pair under consideration. The angle subtended by one pair of poles in a P-pole machine (or one cycle of flux distribution) is defined to be 360 electrical degrees,or2π electrical radians. So the relationship between the mechanical angle m and the angle in electrical units is given by
because one complete revolution has P/2 complete wavelengths (or cycles). In view of this relationship, for a two-polemachine, electrical degrees (or radians)will be the same asmechanical degrees (or radians).
In this section we set out to show that a rotating field of constant amplitude and sinusoidal space distribution of mmf around a periphery of the stator is produced by a three-phase winding located on the stator and excited by balanced three-phase currents when the respective phase windings are wound 2π/3 electrical radians (or 120 electrical degrees) apart in space. Let us consider the two-pole, three-phase winding arrangement on the stator shown in Figure.
The windings of the individual phases are displaced by 120 electrical degrees from each other in space around the air-gap periphery. The reference directions are given for positive phase currents. The concentrated full-pitch coils, shown here for simplicity and convenience, do in fact represent the actual distributed windings producing sinusoidal mmf waves centered on the magnetic axes of the respective phases. Thus, these three sinusoidal mmf waves are displaced by 120 electrical degrees from each other in space. Let a balanced three-phase excitation be applied with phase sequence a-b-c, ia = I cos ωs t ; ib = I cos(ωs t - 120°); ic = I cos(ωs t - 240°) where I is the maximum value of the current, and the time t = 0 is chosen arbitrarily when the a-phase current is a positive maximum. Each phase current is an ac wave varying in magnitude sinusoidally with time. Hence, the corresponding component mmf waves vary sinusoidally with time. The sum of these components yields the resultant mmf.
what is norton''s theorm?
The method by which electrical signals convey information has been described. Systems components have been selected and interfaced to enable a chosen system to perform a desired o
The Parallel Resistance rule Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4
What do you understand by SEGMENT assembler directive? SEGMENT: This directive explains to the assembler the start of a segment along with name segment-name. The segment
Q. Describe about transmission-line voltage regulation? The transmission-line voltage regulation (TLVR) is the ratio of the per-phase voltage drop between the sending-end and r
Explain Atomic structure and Energy Band Diagram of Germanium. Germanium : This is one of the most common semiconductor material utilized in the application in electronics.
Q. The first four harmonics in the Fourier series of current waveform given by where I m = 15 mA and T = 1 ms. If such a current is applied to a parallel combination of R
Next, let us consider the case of a balanced delta-connected load with impedance of 5 45° supplied by a three-phase, three-wire 100-V system, as shown in Figure (a). We shall dete
A rifle with a mass of 3,5 kg fires a bullei with a mass of 120 g with a muzzle velocity of 420 mls. Calculate the following: 1.4.''l The momentum before the rifle was fired ''1.4.
Register Addressing In this mode the operand are microprocessors registers only i, e the operations is performed within various registers of the microprocessors only.
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