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.
parameters in designing a presure vessels
Mr. Moody has decided to invest at most N$100 000 in securities in the form of corporate stocks. He has classified his options into three groups of stocks: blue-chip stocks that he
Q . Determine MI of unequal angle section 15cm × 10cm × 1.5cm with longer leg vertical and is flange upwards. Figure Sol. : A 1 = 10 ×
Question: As shown in the figure, the jet transport B is flying north with a velocity v B = 600 km/h when a smaller aircraft A passes underneath the transport headed in the 60
how to prevent absolute noise during meshing of gears
Hi there. I am stuck on a problem. I am working out the section of 2 beams for the floor of an elevator. Thus far the critical conditions are made up of a beam that is 1.8m long
Calculate the principal dimensions of a cone clutch faced with leather to transmit 30 KW at 750 r.p.m. from an electric motor to an air compressor. Draw a section front view of the
Q. Waste Water Treatment? Typically, there are a number of waste water streams which need to be treated before disposal to land or water. Depending on the nature of contaminati
define environment and explain stockholm conference
Flight of the Bumblebee Railroad train T a leaves station A at a uniform speed of 30mph toward station B. Train Tb leaves station B at a uniform speed of 20mph toward station
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