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.
Clutch cable model: Ensure the cables fitted is of the respective model and not interchanged with other model. Also ensure that the cable is genuine.
how to find view factor for a cylinder to humanbody at a distance?
write a VB programme that compute the binary ordering algorithm for unlimited number of machines and parts
Find power transmitted by cross type belt: Find power transmitted by cross type belt drive connecting two pulley of diameter 45.0cm and 20.0cm that are 1.95m apart. The max
Example of Equilibrium of body on the rough inclined: Magnitude of minimum force ' p ' that is required to move the body up the plane. At the time when ' p ' is acted with the
The following observations were made during a tensile test on mild steel specimen 60 mm in diameter and X mm long. Elongation with 50 KN load (within the limit of proportionality)
Q. Describe Direct extrusion? • Direct extrusion, also known as forward extrusion, is the most common extrusion process. • It works by placing the billet in a heavy walle
Determine the Forces in Members in Roof Truss Determine the forces in members EF, EL, FL, and LK in the roof truss shown below and state whether the members are in tension or
Q. Environmental factors for high temperature service materials? Many environmental factors must also be considered when choosing a material for high temperature service. High
Write the Scope of operation
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