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.
Find out the reactions at point: A beam AB is hinged at A and is supported at C. It is loaded as revealed in Figure. Find out the reactions at A and C. Solution L
ismb 600 load capacity length in 8 meter
Swing Arm Shock Absorber : This type of suspension is used to serve for rear part of motorcycle. The advantage of this type of suspension is that large deflections are absorbed.
Write down the uses of following tools and make neat sketches of the same : (a) Vernier Caliper (b) Steel Rule
WHO IS HOME MINISTER OF INDIA OF 2014?
Determine the maximum bending moment: A 12 m span simply supported beam is carrying a consistently distributed load of 2 kN/m over a length of 6 m from the left end and point
What do you understand by PELE box and when it is utilized? Ans. The equipments required in PELE box are: i. HOLDER ii. TRIPOD STAND iii. BULBS iv. CROCODILE CLIP
WHAT IS DAMP VIBRATION FACE ANGLE SIMPLE HARMONIC MOTION NATURAL CIRCULAR FREQUENCY FORCE VIBRATION
Find out angular displacement of a partical: The angular displacement of a rotating body starting from rest is defined by φ (t ) = 4 t 3 - 3 t 2 . Find out its angular di
torque
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