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.
the movability of 3 bar mechanism is zero then how can we comment on instantaneous centre of it?
In considering a particular fermentation there are a number of choices regarding process operation. Typical initial considerations are listed below. Again, the choices made will d
how to work proell govwrnor?
Explain the Extensive Properties of a System Extensive properties are those, which dependent on the mass of the system and do not maintain similar value for any part of the sys
What is a couple
Define Cases in which Automation is Done Automation is done in following cases:- a) Loading and unloading of parts. b) Automatic production lines. c) Automatic tool ch
construction and working of michelsons interferometer
Steel Rule: A steel rule is used to measure length. It has two scales - in millimeters and inches. These rules are available in market in discrete lengths such as 15, 30, 60 cms.
differentiate between kinematic chain and mechanisms
A long cylinder of radius 2 m hinged at point A is used as an automatic gate. When the water level reaches 15 m the gate automatically opens. Determine the magnitude of the net hyd
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