The armature voltage control of D.C. motor provides_____________?
(A) constant voltage drive
(B) constant current drive
(C) constant torque drive
(D) none of the above
The plugging gives the____________?
(A) zero torque braking
(B) smallest torque braking
(C) highest torque braking
(D) none of the above
For a D.C. shunt motor if the excitation is changed_______________?
(A) torque will remain constant
(B) torque will change but power will remain constant
(C) torque and power both will change
(D) torque, power and speed, all will change
Which motor has the poorest speed control?
(A) Differentially compounded motor
(B) Cumulatively compounded motor
(C) Shunt motor
(D) Series motor
If I2 be the armature current, then speed of a D.C. shunt motor is_______________?
(A) independent of Ia
(B) proportional to la
(C) varies as (Ia)
(D) varies as la
The speed of a D.C. shunt motor can be increased by_______________?
(A) increasing the resistance in armature circuit
(B) increasing the resistance in field circuit
(C) reducing the resistance in the field circuit
(D) reducing the resistance in the armature circuit
As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent a heavy current from flowing though the armature circuit____________________?
(A) a resistance is connected in series with armature
(B) a resistance is connected parallel to the armature
(C) armature is temporarily open circuited
(D) a high value resistor is connected across the field winding
The armature voltage control of D.C. motor provides____________?
(A) constant torque drive
(B) constant voltage drive
(C) constant current drive
(D) none of the above
The speed of a motor falls from 1100 r.p.m. at no-load to 1050 r.p.m. at rated load. The speed regulation of the motor is______________?
(A) 2.36%
(B) 4.76%
(C) 6.77%
(D) 8.84%
Usually wide and sensitive speed control is desired in case of____________?
(A) centrifugal pumps
(B) elevators
(C) steel rolling mills
(D) colliery winders