For constant torque drive which speed control method is preferred ?
(A) Field control
(B) Armature voltage control
(C) Shunt armature control
(D) Mechanical loading system
Ward-Leonard control is basically a____________?
(A) voltage control method
(B) field divertor method
(C) field control method
(D) armature resistance control method
Which motor should not be started on no-load ?
(A) Series motor
(B) Shunt motor
(C) Cumulatively compounded motor
(D) Differentially compounded motor
Why are the D.C. motors preferred for traction applications ?
(A) Torque and speed are inversely proportional to armature current
(B) Torque is proportional to armature current
(C) Torque is proportional to square root of armature current
(D) The speed is inversely proportional to the torque and the torque is proportional to square of armature current
If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will_________?
(A) increase
(B) decrease
(C) remain same
(D) become zero
If the terminals of armature of D.C. motor are interchanged, this action will offer following kind of braking?
(A) regenerative
(B) plugging
(C) dynamic braking
(D) none of the above
(D) any of the above
If a D.C. motor designed for 40°C ambient temperature is to be used for 50°C ambient temperature, then the motor_____________?
(A) of lower H.P. should be selected
(B) of higher H.P. should be selected
(C) can be used for 50°C ambient temperature also
(D) is to be derated by a factor recommended by manufacturer and select the next higher H.P. motor
In a manual shunt motor starter?
(A) over load relay is connected in series and no volt relay in parallel with the load
(B) over load relay is connected in parallel and no volt relay in series with the load
(C) over load relay and no volt relay are both connected in series with the load
(D) over load relay and no volt relay are both connected in parallel with the load
D.C. shunt motors are used for driving____________?
(A) trains
(B) cranes
(C) hoists
(D) machine tools
Torque developed by a D.C. motor depends upon_____________?
(A) magnetic field
(B) active length of the conductor
(C) current flow through the conductors
(D) number of conductors
(D) radius of armatureF. all above factors