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.
Reciprocatin Compressor. It is taken in use to compressor gases. ( kE 2 - kE 1) = 0, ( pE 2 - pE 1) = 0 q 1-2 - w 1-2 = ( h 2 - h 1 ) + 0 + 0 - q 1-2 - (- w
Fuel Feed System: Fuel feed system is provided to serve the air fuel mixture to the engine in an appropriate ratio so that it can burn efficiently and transmit power to crank shaf
the pump, shown in the figure, is used to deliver water to a distribution system. there is no flow to or from reservoir A, but it is used to damp pressure and protect the pump. th
Q. What do you mean by Weld and hold time? Weld time During this period the welding current flows through the circuit, i.e., it enters from one electrode, passes through t
Question: A series resistive inductive load is energised from a 240V (RMS), 50Hz single phase AC supply, such that the load draws 1200W at a power factor of 0.8. a) Calculat
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
A heating section consists of a 10 in diameter duct which houses a 8 kW electric resistance heater. Air enters the heating section at 14.7 psia 40oF, and 35 percent relative humidi
How to drill 500 sheets paper ?in 4 mm dia , holes are same distance as its dia (4mm) in one line.
instant center of direct contact slider
The background for the oil storage tank failure is as follows: the tank involved was a four million gallon circular tank that was built in 1940 for Ashland Oil Company in Cleveland
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