A 3-phase, Y=-connected, 440 V, 20-kW, 50 Hz, 1450 rpm wound roto induction machine has the following parameters in ohms: R, = 0.25 R = 0.2, X, = 1.0, X; = 0.8 and Xm = 30, where R, and X are referred to stator. The total friction, windage and core losses may be assumed to be constant at 1000 W, independent of load. (a) Draw the approximate equivalent circuit. (b) Using the approximate equivalent circuit in (a), operating as a motor determine (i) the full-load developed torque (ii) the maximun developed torque and the corresponding speed (iii) the starting torque. (c) How much resistance must be inserted in the rotor circuit to bring the machine speed at maximum torque down to 1250 rpm?

A 3-phase, Y=-connected, 440 V, 20-kW, 50 Hz, 1450 rpm wound roto induction machine has the following parameters in ohms: R, = 0.25 R = 0.2, X, = 1.0, X; = 0.8 and Xm = 30, where R, and X are referred to stator. The total friction, windage and core losses may be assumed to be constant at 1000 W, independent of load. (a) Draw the approximate equivalent circuit. (b) Using the approximate equivalent circuit in (a), operating as a motor determine (i) the full-load developed torque (ii) the maximun developed torque and the corresponding speed (iii) the starting torque. (c) How much resistance must be inserted in the rotor circuit to bring the machine speed at maximum torque down to 1250 rpm?

Introductory Circuit Analysis (13th Edition)

13th Edition

ISBN:9780133923605

Author:Robert L. Boylestad

Publisher:Robert L. Boylestad

Chapter1: Introduction

Section: Chapter Questions

Problem 1P: Visit your local library (at school or home) and describe the extent to which it provides literature...

See similar textbooks

Similar questions

4) A 40-kW induction motor, with a lagging power factor of 0.76 is supplied by a 120-Vrms, 60-Hz sinusoidal voltage source. Find the capacitance needed in parallel with the motor to raise the power factor to 0.9 lagging
Electrical Engineering Consider a balanced 3-phase current flowing into the stator of a 2-pole induction motor. What should be the current expressions for a clockwise rotation of the magnetic field? For wt = 10, 100,200,300 show that the rotating magnetic field is actually rotating clockwise using stator conductor
QUESTION 1 a) Write down three (3) factors that will determine the induced torque in a DC machine. b) Explain why higher voltage applied to a motor doesn't always mean that it will have a higher induced torque. You can give an example of the scenario to answer this question. c) When a motor is powered up and rotates, it will induce an internal generated voltage. Is this statement true or false? Justify your answer. d) For the core design shown in Fig. 1: i. Design the magnetic circuit model. Indicate clearly for each part that you use in the magnetic circuit which part of the core is represented. ii. Predict what will happen to the total reluctance if the depth is increased. Justify your answer. rl r2 r4 9 cm 9 cm -25 cm 15 cm to -25 cm- 9 cm 2 A 200 turns -0.04 cm 25 cm 9 ém
A 3 phase, 50 Hz. 2 pole alternator is excited to generate the bus ber Example 3.32.5 voltages of 11 kV at no load, Calculate the synchronizing power per degree of mechanical displacement of the rotor. The machine is star connected and the short circuit current for this excitation is 1200 amperes. Neglect armature winding resistance
A 6 pole, wave wound DC shunt generator has a useful total flux of 420 mWb. The armature winding consists of 220 turns each of 0.004 2 resistance, when running at 900 RPM the armature current is 50 A. If the armature winding reconnected as lap calculate the terminal voltage in case of wave and lap given that the field circuit and the speed are kept same.
The armature winding resistance of a long shunt connected DC generator is 0.4ohm, the resistances of the shunt and serial field windings are 125 ohms and 0.1 ohms, respectively. While the generator supplies 8KW of power to the load it feeds, which is the voltage it produces since the output voltage is 250V?
A DC machine has total armature ampere conductors of 4500 and total flux in the machine is 0.14 wb. The torque developed in the machine is (in N-m/rad)
A 220 V , 60 Hz , supply is connected to 200 – turn armature winding of reluctance 1.7x105 At / Wb . Find the magnetizing reactance , the rms values of the ( magneto – motive force , exciting and armature currents , magnetic flux ) , and the inductance Draw the phasor diagram of the circuit .
An eight-pole, 24 KW, 180 V, DC machine has a duplex LAP-wound armature which has 72 coils with 10 turns per coil. Its rated speed is 2400 RPM. Assume a dead zone of 4 coils that are always beyond poles faces. Find the constant K, and the flux per pole to produce 180 V at no-load conditions. Answers The constant K is : The flux per pole is: mWb/pole.
If the average pole flux of a dc machine with 24 coils, each of which contains 16 windings, 4 poles, double layered parallel winding (duplex lap winding), with a speed of 1000 rpm, is 15mWb, what is the idle winding voltage and (Note: In your operations, two digits after the comma) take it)
the armature of a 12 pole wave wound dc shunt generator has 50 slots with 12 conductors per slot. the generatoris running at a speed of 625 rpm and supplies a resistive load of 15 ohm at a terminal voltage 350v. the armature and the field reisitance are0.5 ohm and 70 ohm respectively. find the armature current,generated emf and flux per pole
Two DC generators, each with armature resistance of 0.02 ohm and fieldresistance of 50 ohms run in parallel and supply a total current of 1000 amperesto the load circuit. If their emfs are 270 V and 265 V, their bus bar voltagewill be. [Ans. 267.5 V]