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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.
Define the X-NOR or Exclusive-NOR Gate? This is the EX-OR gate with the output inverted, as shown by the 'o' on the output and the output Q is true if inputs A and B a
find the resultant of two forces 20N and25N acting at an angle 60 degree each other
Evaluate currents in the circuits: Determine currents I 1 and I 2 in the given circuits by applying KVL. Solution We apply KVL for first loop : 10 = 1 I 1 + 1 (
Level 1 is means of sending bit streams over a physical path. It uses times lot 16 of a 2 M bit/s PCM system or times slot 24 of a1.5 M bit/s system. Level 2 performs functions
Q. What do you mean by Insurance? This is done by creating a common fund out of the contribution (known as premium) from several persons who are equally exposed to the same los
Given: R 1 = R 3 = 1 k_, R 2 = 100 k_ and k = 0.1 A/V, and step-up transformer turns ratio is 10. a) Find the value of the load resistor RL that would maximize the power
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2365-305 Electrical systems design TASK A
Explain P - N junction. P - N junction: If a p- type semiconductor is properly joined to an n-type semiconductor the contact surface that formed is termed as p-n junction. Th
PID controllers are popularly adopted in a wide range of industrial processes. The objective of this design practical is to study the way this PID controller changes system dynamic
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