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.
Q. Minimal external force required to achieve alignment? Minimal external force shall be applied to achieve alignment. Flanged joints not conforming to the dimensional toleranc
Q. Which functions used for coating? • Improves arc stability by providing certain chemical which have this ability, by ionizing the path of arc. • Provides a protective gaseou
I have experimental results for a 2D model and a matlab script that computes the aerodynamic loads on that 2D model.When we compare experiment with the theory I have noted that the
Determine the dead load: A 250 mm diameter sewer is placed in a 2.75 m deep rectangular trench that is 0.65 m wide. This trench is backfilled with saturated clay having a unit
Explain Wilson HArtnell Governor
Compare otto cycle with Diesel cycle: Sol.: These two cycles can be compared on the basis of either the same compression ratio or the same maximum pressure and temperature.
Q. Describe Cold extrusion? • Cold extrusion is done at room temperature or near room temperature. • The advantages of this over hot extrusion are the lack of
Gears : A gear is a disc with teeth on its boundary. If these teeth are formed at its inner boundary then this gear is known as an internal gear (annulus). These types of gears ar
In an orthogonal cutting test with a tool of rake angle 10 degree , the following observations were made. 20 Chip thickness ratio = 0.3 Width of cut = 6mm Uncut chip thicknes
Explain the Single Cast Component Auger Material for Single Cast Component Auger: Either Ni-Cr or Cast iron Length of components: 1250 mm. Outer Diameter of Auger compone
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