please solve question 8 3-phase A-connected induction motor has a direct starting current of 800 % ofrated current and a full-load slip of 4 %. Answer the following questions:(a) Under direct starting conditions, calculate the percentage of the starting torquecompared to rated torque.(b) If an autotransformer is used to reduce the starting current of the motor to 250% of rated value, calculate the transformation ratio of the transformer, and thecorresponding percentage value of the new starting torque.(c) If the motor is to be started using Y-A starting method, calculate the newpercentage of the starting current and the corresponding starting torque.laging(6) A 4 MW, 0.707 industrial plant is supplied from a 6 MVA three-phase powertransformer. A 1.0 MW, 11 kV, 0.8 leading power factor, 88 % efficient, 3-phasesynchronous motor is to be installed in the plant. Answer the following questions:Case(a) What is the new overall power factor of the plant.(b) Is the 6 MVA transformer over-loaded after connecting the synchronous motor.(c) If yes find the over-loading percentage.(7) A 500 V, A-connected, three-phase synchronous motor has an EMF of 600 V. Themotor synchronous impedance is (0.4+j5) 02/ph, and the rotational losses areneglected.Calculate the maximum power output that can be delivered, the corresponding linecurrent, the input power factor and efficiency of the motor.(8) A 3300 V, A-connected synchronous motor has a synchronous reactance of 18 0/ph.It operates at a 0.707 leading power factor when drawing 800 kW from the mains.Answer the following questions:(a) Calculate the motor EMF and torque angle.(b) If the field current in increased by 20 % while the load power is unchangedcalculate the new value of the line current and the corresponding input powerfactor.

Answered: Image /qna-images/answer/7276ab8a-5e05-44c0-91ec-8f1c4f200726.jpg

It oper Answer the following questions: (a) Calculate the motor EMF and torque angle. (b) If the field current in increased by 20 % while the load power is unchanged calculate the new value of the line current and the corresponding input power factor.

It oper Answer the following questions: (a) Calculate the motor EMF and torque angle. (b) If the field current in increased by 20 % while the load power is unchanged calculate the new value of the line current and the corresponding input power factor.

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. for three phase induction motor, the decreasing in the starting torque when the motor started by means of an auto-transformer having a 60 percent voltage tap is equal to
A freewheeling DC motor is driven with 1000 rpm and a nominal load torque of 80Nm. The field circuit resistance is 200 and the armature circuit resistance is 0.2 O. The field coils are fed with a zero degree transmission angle through a single-phase fully controlled converter connected to a single-phase 240V source. The armature circuit is fed from a single phase 400V source through another fully controlled converter. Magnetic saturation has been neglected, the motor constant is given as 0.8 V - s / A - rad. Assuming that there is no fluctuation in armature and field current, find the control angle of the converter feeding the armature at nominal load. If you want to leave the question blank, click again on the option you marked.
An 3-phase induction motor(IM) has full load slip = 0.5%. If the rotor circuit resistance is increased so that R2new =2R2old, then the slip at which the motor develops the same full load torque is=.. * ......
An 8 pole, 50 Hz slip ring induction motor runs at a slip of 2.67% on full load. The rotor resistance per phase of the winding is 0.2 ohm. What external resistance per phase must be added in the rotor circuit so that the motor now runs ate a slip of 17.33% such that the torque remains same in both the cases. (Ans: 1.1 ohm)
A 3 – phase induction motor has a 4 – pole, star – connected stator winding. The motorruns on a 50 – Hz supply with 200 V between lines. The rotor resistance and standstillreactance power phase are 0.1 and 0.9 ohm respectively. The ratio of rotor to stator turnsis 0.67. Calculate (a) total torque at 4 % slip, (b) total mechanical power at 4 % slip, (c)maximum torque, (d) speed at maximum torque, (e) maximum m power
Torque-speed characteristics for three phase induction motor 4. Discuss the following (rated torque, starting torque, break down torque).
The use of a series capacitor with the auxiliary windings of a single-phase induction motor permits: * The obtaintion a 90-degrees phase angle between currents in the main and auxiliary windings. The garantee a relatively high starting torque all above
g) What is an advantage if the starting Torque of the induction motor is higher than the nominal load Torque? h) What are the main differences when the equivalent circuits of transformer and asynchronous motor are examined?
What are the various losses in an induction motor? On what factors do they depend? IV. V. List the different types of stray load losses in an induction motor.
(Question 1): Discuss the following statements briefly: 1. Can use static rotor resistance method to speed control in slip ring induction motor but cannot used in squirrel cage induction motor. 2. adding centrifugal switch in split single phase induction motor 3. Speed Control by Changing the Rotor Resistance 4. Y-A connected transformer is very suitable for step-down applications. 5. After performing an experiment on the Capacitor Start induction motor to determine the effect of changing the value of the starting capacitor on the starting operation of the motor it clarified that the higher the starting capacitor, the greater the starting torque of the motor.
1.why the slip of induction motor is never zero, 2.what happens if the slip of induction motor is one, 3.what is the value of the slip for an induction motor at on load and full load
2. Describe the Torque-Slip characteristics of a three phase induction motor.