Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
A 4- pole DC motor is known to have an armature resistance of 0.5 Ω, and is operated as a separately excited motor.
(a) When the motor is connected to a 250V DC supply with no external mechanical load and with rated field current, it runs at a speed of 1488 rpm with an armature current of 4A. Calculate the no load rotational losses under these conditions.
(b) The motor is now mechanically loaded until the armature current reaches 40A, under which conditions the DC supply voltage sags to 245V. Calculate the motor speed if the field current is unchanged.
(c) Assuming that the motor rotational losses vary proportionally with speed, calculate the motor efficiency under the load condition of (b).
(d) The motor field current is now accidentally set to half rated value. Calculate the DC supply voltage that is required to return to the same no load operating conditions of part (a)
(HINT: remember that the rotational power losses must stay the same if the speed is unchanged).
(e) Discuss the two possible ways of achieving variable speed operation for a DC machine. Show the torque speed characteristics of a DC motor operating under both these types of speed control strategies, and discuss how they relate to the concepts of the "constant torque" and "constant power" regions of variable speed operation. Discuss the advantages and disadvantages of each speed control strategy.
A Torsion dynamometer is used in a propeller shaft of a marine Engine. It is found that the shaft twists 2 o in a length of 20 meters at 120 r.p.m. If the shaft is hollow with 300
teori heat transfer conduction
Calculate for the resultant of the force system: A rectangle ABCD is having sides AB = CD = 80 mm and BC = DA = 60 mm. Forces of 150 N each of them act along AB a
Types of belts and drive
Figure : Front Top View of the Motorcycle Part No. Part Name Functions 1 Turn signal switch Used to give
Forecasting System Outputs: In a company, inventory level is reviewed biweekly. If the parts used in an assembly have the lead time of one and a half week, what period should
Points of Contraflexure: Assume M 1 , M 2 , . . . and M 6 be the points of contraflexure, where bending moment changes sign. To determine the position of M 2 , let a section
Die Press Assembly Drawing The objective of this assignment is to demonstrate the following concepts of design. • Extrude • Revolve • Fillet • Dimensioning • Tolerance • Bas
Describe Mould Surface Coating? Mould surfaces are coated (after the pattern is drawn out) with certain materials possessing high refractoriness. It eliminates the poss
A helical compression spring prepared of oil tempered carbon steel, is subjected to a load which goes from 600 N to 1600 N. The spring index is 6 and the design factor of safety is
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd