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.
Maximum shear stress and angle of twist: Torques are applied on the shaft as illustrated in Figure. Discover in which portion of the shaft, maximum shear stress & angle of twi
RESISTANCE WELDING The types are as follows: Resistance Spot Welding Resistance Seam Welding Projection Welding Flash Butt Welding Flash Butt Welding Stit
how to calculate the distribution of shear force and bending moment for a simply supported beam
why is physical properties of materials important in design and for industrial application?
For a theoretical OTTO cycle operating on compression ratio of 8.5:1taking in air at 15C and 101.3kPa and having a maximum cycle temp of 1800C.Calculate the temp after compression,
what is the essentials of a good boiler?
How to solve wedge problems..can anyone just explain the method..
Dismantle crank case and explode main shaft , counter shaft, gear shifter drum and kick spindle assembly and check sequence of parts fitment while dismantling: Check all gear teeth
Theoretical Results In the particular machine case, several theoretical results are identified or can be derived: (a) If each operation can be scheduled such that everyone
Strain energy stored in a body due to impact load
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