A shunt DC motor operates at 700 rpm when an armature of 18 A from a 230-V supply. If the armature resistance is 0.25W, calculate the no-load speed, assuming that all output losses are negligible.
A.
700.0 rpm
B.
778.5 rpm
C.
714.0 rpm
D.
687.2 rpm
2.
Find the output torque of a DC motor whose output power is 1200 W and whose shaft speed is 1200 rpm.
A.
1.00 Nm
B.
60.0 Nm
C.
0.105 Nm
D.
9.55 Nm
3.
A 110V series DC motor has an armature resistance of 0.3W and a field resistance of 0.2W. The motor is running off a 110V DC power supply and draws a line current of 20A and rotates at 1500 rpm while driving a mechanical load. The rotational loss of the motor is 250W. Calculate the efficiency of the motor.
A.
79.55%
B.
70.45%
C.
87.5%
D.
61.36%
4.
A 3-phase, 6-pole, induction motor is supplied with a 240V, 50 Hz supply and draws a current of 35A at a power factor of 0.75 and has a full-load slip of 2.0%. The total copper loss and iron loss in the stator is 350W. Calculate the input power, P_{in, } of the induction motor.
A.
14198 W
B.
10562 W
C.
10912 W
D.
14548 W
5.
A 4-pole induction motor is energised by 3-phase, 50 Hz supply. The motor (rotor) runs on full-load at 5 percent slip. Determine:- (i) The speed of the rotating magnetic field (n_{s}) (ii) The frequency of the stator currents (f_{s})
A.
1,500 rpm, 50 Hz
B.
1,500 rpm, 2.5 Hz
C.
1,425 rpm, 50 Hz
D.
1,425 rpm, 2.5 Hz
6.
A DC shunt motor is connected to 230 V DC power supply. The motor has an armature resistance of 0.8 ohm and a field resistance of 100 ohms. The motor draws a current of 12A and rotates at 300 rpm at full load. Find the input power.
A.
2760 W
B.
3000 W
C.
2880 W
D.
529 W
7.
In the 3-phase induction motor, if the rotor moves at the same speed as the magnetic field
A.
The slip will be 1
B.
The torque will be maximum
C.
The slip will be zero
D.
The torque will remain unchanged
8.
A 100V DC series motor runs at 1500 rpm with a line current of 20A. The armature resistance is 0.3W and the field resistance is 0.2W. Find the power developed.
A.
1800 W
B.
1880 W
C.
1920 W
D.
2000 W
9.
An induction motor is running at a slip of 0.1. The input power is 2000W. The stator copper loss and core loss is 200W. The rotational loss is 50W. What is the rotor copper loss?
The Industrial Revolution is the name given the movement in which machines changed people's way of life as well as their methods of manufacture. Wear your thinking caps, take the quiz, and answer the following...
Questions: 10 | Attempts: 24523 | Last updated: Mar 22, 2022