Electric Motor Control
10th Edition
ISBN: 9781133702818
Author: Herman
Publisher: CENGAGE L
expand_more
expand_more
format_list_bulleted
Concept explainers
Videos
Textbook Question
Chapter 39, Problem 15SQ
A synchronous motor can be used to increase the power factor of an electrical system by
- a. reducing the speed.
- b. overexciting the stator field.
- c. operating at unity power factor.
- d. applying DC to the stator field.
Expert Solution & Answer
Trending nowThis is a popular solution!
Students have asked these similar questions
A synchronous motor is running at 100 percent of rated load with unity power factor. If the field current is increased, how do the following quantities change? a. output power; b. mechanical speed; c. output torque; d. armature current; e. power factor; f. torque angle.
A synchronous motor is running at 75 percent of rated load with unity power factor. If the load increases to the rated output power, how do the following quantities change? a. field current; b. mechanical speed; c. output torque; d. armature current; e. power factor; f. torque angle.
A 6-pole, 50-Hz squirrel-cage induction motor runs on the load at a shaft speed of970 rpm. Calculate a) the percentage slip and b) the frequency of the inducedcurrent in the rotor.
Chapter 39 Solutions
Electric Motor Control
Ch. 39 - Prob. 1SQCh. 39 - What is the effect of the starting winding of the...Ch. 39 - What are typical applications of synchronous...Ch. 39 - Prob. 4SQCh. 39 - A loaded synchronous motor cannot operate...Ch. 39 - Why must a discharge resistor be connected in the...Ch. 39 - Depending on their power factor ratings, what is...Ch. 39 - At what power factor do incandescent lights...Ch. 39 - Prob. 9SQCh. 39 - The speed of a synchronous motor is fixed by the...
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, electrical-engineering and related others by exploring similar questions and additional content below.Similar questions
- A 20 hp, 440 V, 60 Hz, three-phase star connected synchronous motor has an armature resistance per phase of 0.40 ohm. It is giving its full load output at a power factor of 0.9 leading. If the stray power losses amount to 500 watts, find the armature current.arrow_forwardQ#1: a) What is the operating principle of induction motor? b) Differentiate between induction motor and synchronous motor; give at least one practical example. c) What are the principle characteristics of DC series motor and DC compound motor, and what are its uses?arrow_forwarda. Explain the principle of operation of a shunt DC motor b. Give a brief description of a Synchronous Generator with round rotor.arrow_forward
- A 3-phase 9-pole,50Hz, star connected induction motor has an emf 520 V(L-L). The stator winding has a synchronous reactance of 2.5 Ohms/phase. Induction machine operates at rated voltage and at a leading power factor of 0.85. Shaft power is 15 Kw and the excitation emf is 500 V. (a). Determine the load angle, armature current in per unit and the power factor of the alternator. (b). The alternator is now made to operate at another value of excitation emf which results in the same values of power output and armature current. Under these conditions, find the excitation voltage, load angle and the power factor. (c) If the excitation in (a) and that obtained in (b), which is more likely to be used in practical situations and and why? (d) With the alternator output remaining constant, the alternator excitation is increased by 15%. Find the new values of armature current, load angle and pf? (e) Calculate the total steam output of the alternator delivered to the prime mover? (f) Draw the…arrow_forward(a).i. Describe the construction of a DC generator.ii.Describe the principle of opeartion of a three phase induction motor.b) Explain the power angle characteristics curve of a synchronous machine. c) A shunt generator delivers 450A at 230 V and theresistance of the shunt field and armature are 50Ω and 0.03Ωrespectively. Calculate the generated e.m.f.?arrow_forwardA four-pole, three-phase induction motor drives aturbine load. At a certain operating point the machinehas 4 percent slip and 87 percent efficiency. The motordrives a turbine with torque–speed characteristic givenby TL = 20 + 0.006ω2. Determine the torque at themotor-turbine shaft and the total power delivered tothe turbine. What is the total power consumed by themotor?arrow_forward
- a. A 12-pole 60-Hz synchronous motor drives a 10-pole synchronous machine that acts as a generator. What is the frequency of the voltages induced in the armature windings of the generator? b. Suppose that we need to drive a load at exactly 1000 rpm. The power available is 60-Hz three-phase. Diagram a system of synchronous machines to drive the load, specifying the number of poles and frequency of operation for each. (Multiple correct answers exist.)arrow_forwardA 2000 V,3 phase, 4 pole, star connected synchronous motor has a frequency of 60 Hz. The excitation voltage is constant at 2000 V (line-line)The resistance is negligible as compared to synchronous reactance of 3 ohm per phase. For a lagging constant armature current of 150 A, 2.a) the power factor is In problem #, with the same given information, the power input isarrow_forwardAnswer the followig.a. Give the two main categories of AC motors. Define.b. Discuss the constructional and working difference of Induction and synchronous motor.arrow_forward
- A 3-phase, star connected 400-V synchronous motor takes a power input of 5472 watts at rated voltage. Its synchronous reactance is 10 ohm per phase and resistance is negligible. If its excitation voltage is adjusted equal to the rated voltage of 400 V calculate the load angle, power factor and the armature current.arrow_forwardIn a 4-pole, 50 Hz single-phase Induction motor, the power absorbed by the forward and backward field rotor equivalent resistances are 200 W and 21W respectively at a motor speed of 1440 rpm. The mechanical losses totals 20W. Compute the shaft torque at the above speed.arrow_forwardThree phase 460 hp,415v,4pole,50hz induction motor is operating at Over voltage of 480v and reduced load of 80% of the rated value and draws a line current of 624.06A.The losses at these operating conditions are as follows .The stator conductor loss is 12.6 kw sketch the power flow diagram ,enter the known values and determine (a) rotor speed,(b) shaft output torque ,(c)developed mechanical torque in Nm (d)input power to the stator (f)The input power factorarrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
Introductory Circuit Analysis (13th Edition)Electrical EngineeringISBN:9780133923605Author:Robert L. BoylestadPublisher:PEARSON
Delmar's Standard Textbook Of ElectricityElectrical EngineeringISBN:9781337900348Author:Stephen L. HermanPublisher:Cengage Learning
Programmable Logic ControllersElectrical EngineeringISBN:9780073373843Author:Frank D. PetruzellaPublisher:McGraw-Hill Education
Fundamentals of Electric CircuitsElectrical EngineeringISBN:9780078028229Author:Charles K Alexander, Matthew SadikuPublisher:McGraw-Hill Education
Electric Circuits. (11th Edition)Electrical EngineeringISBN:9780134746968Author:James W. Nilsson, Susan RiedelPublisher:PEARSON
Engineering ElectromagneticsElectrical EngineeringISBN:9780078028151Author:Hayt, William H. (william Hart), Jr, BUCK, John A.Publisher:Mcgraw-hill Education,
Introductory Circuit Analysis (13th Edition)
Electrical Engineering
ISBN:9780133923605
Author:Robert L. Boylestad
Publisher:PEARSON
Delmar's Standard Textbook Of Electricity
Electrical Engineering
ISBN:9781337900348
Author:Stephen L. Herman
Publisher:Cengage Learning
Programmable Logic Controllers
Electrical Engineering
ISBN:9780073373843
Author:Frank D. Petruzella
Publisher:McGraw-Hill Education
Fundamentals of Electric Circuits
Electrical Engineering
ISBN:9780078028229
Author:Charles K Alexander, Matthew Sadiku
Publisher:McGraw-Hill Education
Electric Circuits. (11th Edition)
Electrical Engineering
ISBN:9780134746968
Author:James W. Nilsson, Susan Riedel
Publisher:PEARSON
Engineering Electromagnetics
Electrical Engineering
ISBN:9780078028151
Author:Hayt, William H. (william Hart), Jr, BUCK, John A.
Publisher:Mcgraw-hill Education,
Working of Synchronous Motor; Author: Lesics;https://www.youtube.com/watch?v=Vk2jDXxZIhs;License: Standard Youtube License