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.
An aircraft moving with speed of 1200 Km/hr, uses simple air refrigeration cycle for air conditioning. The ambient temperature and pressure are 0.35 bar and - 10 o C respectively.
CAPP for Casting and Welding In this , we have studied the CAPP systems for Casting and Welding processes. Compared to the traditional (manual) process planning methods, CAPP
Determine the maximum stress: A laminated spring of the quarter elliptic type, 0.6 m long, is to give a static deflection of 80 mm under an end load of 2000 N. If the leaf mat
What is strap footing? Strap Footing You have to use cantilever or strap footings when the proximity of a property line precludes the use of other types for example an isola
Q. Explain about Hydrostatic Test? All paragraph must be met when the hydrostatic test is employed. UG-99(b), including footnote 32, shall be considered to be the standard hyd
The Winged-Edge Representation Perhaps the oldest data structure for a b-rep is Baumgart's winged-edge data structure. It is quite different from that of a wire-frame model, be
What is the amount of air is supplied to engine via turbochargers and how their sizes vary from engine to engine ?
sir/madam, i would like to teach online how can i have to proceed
maximum production rate
Explain the Cost analysis of radial drilling machine Cost regarding to Manual arrangement of auger extension in paver machine: 1.cost of segmented angle radial drill machin
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: +1-415-670-9521
Phone: +1-415-670-9521
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd