the induction machine handbook chuong (27)

... 0.04) the current goes down and so does the torque, coming close to the rated value, which corresponds, to the rated power P n (27.58). On the other hand, if the slip is gradually increased the ... fan load, at 50% as the low speed, the torque is 25 % and thus the locked rotor torque has to be less than 25%. We start with the sizing of the magnetic circuit, mo...

Ngày tải lên: 21/03/2014, 12:13

... and testing for induction machines • Integral induction motors: induction motors with the PWM converter integrated into one piece 1.3. INDUCTION MACHINES IN APPLICATIONS Induction motors ... closed) windings of the rotor. The interaction between the stator produced field and the rotor induced currents produces torque and thus operates the induction motor. As...

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... conductors on the part of the machine not connected to the grid (the rotor, or the mover in general), - the secondary. If the windings on the secondary (rotor) are closed, a.c. currents occur in the ... phase. In both cases the winding arrangement on the part of the machine the primary–connected to the grid (the stator in general) should produce a traveling f...

Ngày tải lên: 21/03/2014, 12:13

... this combination. The insulation of the coil conductors (turns) is applied before inserting the coils in slots. The coils are vacuum also impregnated outside the machine. The slot insulation ... ……… The connections between the coils of a phase and the leads to the terminal box have to be insulated. Also the binding cord used to tie down endwindings to r...

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... and the other side in the second layer. They are connected observing the inward (A, B, C) and outward (A’, B’, C’) directions of currents in their sides.  Connecting the coils per phase The ... Having two current paths, the current in the coils is half the current at the terminals. Consequently, the wire gauge of conductors in the coils is smaller and thus the c...

Ngày tải lên: 21/03/2014, 12:13

... calculated for the fundamental airgap flux density. This information prepares the ground to define the parameters of the equivalent circuit of the induction machine, that is, for the computation ... r m4 , (for the stator) and r m2 (for the rotor). Assuming that the radial magnetic field H is constant along the circles r m2 and r m4 , the flux linkage equivalenc...

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... The airgap flux does not reach the other slotted structure (Figure 6.10a) while the zig-zag flux “snakes” out through the teeth around slot openings. In general, they may be treated together ... rotor phases. In reality the flux in the rotor varies at Sf 1 frequency, while in the stator at f 1 frequency. The amplitude is the same and, with respect to each other, th...

Ngày tải lên: 21/03/2014, 12:13

... addition to the emf, there is only the stator resistance and leakage inductance voltage drop. Finally, as there is current (mmf) in the rotor, the emf E 1 is produced concurrently by the two ... constitute the IM equations per phase reduced to the stator for the rotor circuit. Notice that in these equations there is only one frequency, the stator frequency ω 1 , whic...

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... constant under steady state and the machine behaves like a synchronous machine with the torque dependent on the power angle δ (S = f 2 /f 1 = ct). On the other hand, the frequency f 2 may be varied ... when the load torque decreases, to reduce the flux level in the machine and thus reduce the core losses and increase the power factor and efficiency while stato...

Ngày tải lên: 21/03/2014, 12:13

... obtain their real values. On the other hand, Equations (9.35) – (9.36) lead to the equivalent circuit in Figure 9.12. Once the layer currents I 1 , … I n are known, the total losses in the bar ... 9.4. SKIN EFFECT IN THE END RINGS VIA THE MULTILAYER APPROACH As the end rings are placed in air, although rather close to the motor laminated stack, the skin effect in...

Ngày tải lên: 21/03/2014, 12:13