Testbook Logo
Exams SuperCoaching Test Series Skill Academy
More
English
Hindi

Question

Download Solution PDF

Which of the following is a disadvantage of synchronous motor over induction motor for power requirements from 35 kW up to about 2500 kW?

This question was previously asked in
PGCIL Diploma Trainee EE Official Paper (Held on 17 Dec 2020)
Download PDF Attempt Online
View all PGCIL Diploma Trainee Papers >
  1. Cost
  2. Size
  3. Weight
  4. Requirement of DC supply for field

Answer (Detailed Solution Below)

Option 4 : Requirement of DC supply for field
Free Tests
View all Free tests >
Free
CT 1: Classification I
3.3 K Users
10 Questions 10 Marks 10 Mins
Start Now

Detailed Solution

Download Solution PDF

Comparison between Induction Motor and Synchronous Motor for power range 35 kW to 2500 kW:

Particular Synchronous Motor Induction Motor
Speed Constant speed from no load to full load Speed change with load
Power factor Can be operated at all power factor Operate at lagging power factor
Excitation Required DC excitation at the rotor or filed No need for excitation
Economy Economical for speed below 500 RPM Economical for speed above 600 RPM
Starting Auxiliary means have to provide for starting Self-starting
Construction Complicated Simple
Starting toque More Less
Download Solution PDF
Latest PGCIL Diploma Trainee Updates

Last updated on May 9, 2025

-> PGCIL Diploma Trainee result 2025 will be released in the third week of May. 

-> The PGCIL Diploma Trainee Answer key 2025 has been released on 12th April. Candidates can raise objection from 12 April to 14 April 2025.

-> The PGCIL DT Exam was conducted on 11 April 2025. 

-> Candidates had applied online from 21st October 2024 to 19th November 2024.

-> A total of 666 vacancies have been released.

-> Candidates between 18 -27 years of age, with a diploma in the concerned stream are eligible.

-> Attempt PGCIL Diploma Trainee Previous Year Papers for good preparation.

More Synchronous Motor Properties Questions

Q1.A 400V, 3-phase, star-connected synchronous motor has an armature current of 200A at an effective resistance of 0.04 OHMS. The short circuit load loss at half-full load will be _________.
Q2.A 400 V, 3-phase synchronous motor has armature current of 150 A. It has synchronous resistance and reactance of 0.4 Ω and 4 Ω per phase, respectively. If the power developed is 130 kW and the iron and friction losses are 1 kW, then the efficiency of the motor will be ______.
Q3.In synchronous motor, nature of armature reaction is _________ when it draws a lagging power factor current.
Q4.According to the power circle, the efficiency of a synchronous motor at maximum power output is:
Q5.The nature of under excited synchronous motor is:
Q6.A synchronous motor, connected to an infinite bus, is working at a leading p.f. Its excitation e.m.f Ef and alternator terminal voltage Vt are related as
Q7.In a synchronous motor
Q8."Selsyn" is the trade name given to-
Q9.Variation in dc excitation of a synchronous motor causes variation in

More Alternator and Synchronous Motors Questions

Q1.Which statements about voltage drop in an alternator are correct? I. The voltage drop due to armature resistance (IaRa) is in phase with the armature current (Ia). II. At unity power factor, the voltage drop IaRa directly subtracts from the generated EMF (E). III. For a leading power factor load, IaRa contributes to an increase in terminal voltage (V). IV. Armature resistance has no effect on voltage regulation.
Q2.Why are salient pole rotors NOT used in turbo alternators?
Q3.Compared to the MMF method, the EMF method is ___________.
Q4.Which application is a common use of synchronous motors? 
Q5.Under constant mechanical load, changing the excitation of a synchronous motor affects which of the following? I. Power factor II. Armature current magnitude III. Speed of the motor IV. Real power output 
Q6.In an alternator, if the load power factor changes from lagging to leading, the armature reaction effect shifts from:
Q7.Which statements about the maximum power output of a cylindrical rotor synchronous generator are correct? I. Maximum power output occurs when the load angle (δ) is 90°. II. Maximum power is proportional to the square of the terminal voltage (V). III. Over-excitation increases the generator’s maximum power capability. IV. Maximum power is independent of the synchronous reactance (Xs).
Q8.Stray load losses in synchronous motors are caused by __________. 
Q9.In a synchronous motor, If the load angle exceeds 90°, then the motor will: 
Q10.Why are short-pitch windings preferred in alternators despite their lower induced EMF per coil?
Crack Super Pass Live with
India's Super Teachers
Explore Supercoaching For FREE
Suggested Test Series
View All >
AE & JE Civil Engg. Exams Previous Year Papers Mock Test
469 Total Tests with 3 Free Tests
Start Free Test
AE & JE Electrical Engg. Exams Previous Year Papers Mock Test
276 Total Tests with   3 Free Tests
Start Free Test
Suggested Exams
Exam-Logo
SSC JE EE

SSC JE EE Important Links

More Electrical Machines Questions

Q1.If a 6-pole induction motor operates on a 60 Hz supply, its synchronous speed is _____________.
Q2.How are the segments of the commutator insulated from each other?
Q3.Which statements about voltage drop in an alternator are correct? I. The voltage drop due to armature resistance (IaRa) is in phase with the armature current (Ia). II. At unity power factor, the voltage drop IaRa directly subtracts from the generated EMF (E). III. For a leading power factor load, IaRa contributes to an increase in terminal voltage (V). IV. Armature resistance has no effect on voltage regulation.
Q4.What does the flux created by the load current in the primary winding, which links only with the primary winding, represent?
Q5.In distribution transformers, the explosion vent is designed to:
Q6.Why are salient pole rotors NOT used in turbo alternators?
Q7.In the equivalent circuit without core losses, the magnetising branch consists of __________. 
Q8.Compared to the MMF method, the EMF method is ___________.
Q9.Which application is a common use of synchronous motors? 
Q10.The same polarity condition is essential in parallel operation because: 
Exams
Cut Off
Eligibility
Coaching
Previous Year Papers
Syllabus
Test Series
Important Exams
Super Coaching
Testbook USA SAT Exam
Testbook USA ACT Exam
US College Admissions Guide
Testbook Edu Solutions Pvt. Ltd.
1st & 2nd Floor, Zion Building,
Plot No. 273, Sector 10, Kharghar,
Navi Mumbai - 410210
[email protected]
Toll Free:1800 833 0800
Office Hours: 10 AM to 7 PM (all 7 days)
Company
About usCareers We are hiringTeach Online on TestbookPartnersMediaSitemap
Products
Test SeriesTestbook PassOnline CoursesOnline VideosPracticeBlogRefer & EarnBooks
Our Apps
Follow us on
Copyright © 2014-2022 Testbook Edu Solutions Pvt. Ltd.: All rights reserved
User PolicyTermsPrivacy
Get Free Access Now
Hot Links： teen patti apk download teen patti master new version teen patti master download