Related Questions

Sparking, is discouraged in a D.C. motor because
A It increases the input power consumption
B Commutator gets damaged
C Both (A) and (B)
D None of the above
In a lamp load when more than one lamp are switched on the total resistance of the load
A Increases
B Decreases
C Remains same
D None of the above
Sparking at the commutator of a D.C. motor may result in
A Damage to commutator segments
B Damage to commutator insulation
C Increased power consumption
D All of the above
The sparking between two electrical contacts can be reduced by inserting a
A capacitor in parallel with contacts
B capacitor in series with each contact
C resistance in line
D none of the above
In a universal motor, the most common cause of brush sparking is
A open armature winding
B shorted armature winding
C shorted field winding?
D high commutator mica
E all of the above
The voltage required to produce a spark across the gap, between the sparking points is
A 2,000 to 4,000 volts
B 4,000 to 6,000 volts
C 6,000 to 10,000 volts
D 10,000 to 12,000 volts
In a D.C. generator in order to reduce sparking at brushes, the self-induced e.m.f. in the coil is neutralized by all of the following except
A Interpoles
B Dummy coils
C Compensating winding
D Shifting of axis of brushes
When the axis of load lies in the plane of rivet group, then the most heavily loaded rivet will be the one which (where, Fa is the load shared by each rivet due to axial load and Fm is the shearing load due to moment in any rivet.)
A Is at the maximum distance from CG of the rivet group
B Is at the minimum distance from CG of the rivet group
C Gives the maximum angle between the two forces Fa and Fm
D Gives the minimum angle between the two forces Fa and Fm
In testing a pile by load test, pile platform is loaded with one and half times the design load and a maximum settlement is noted. The load is gradually removed and the consequent rebound is measured. For a safe pile, the net settlement (i.e. total settlement minus rebound) per tonne of test load should not exceed
A 10 mm
B 15 mm
C 20 mm
D 25 mm
Which of the following applications always have some load whenever switched on ?
A Vacuum cleaners
B Fan motors
C Pistol drills
D All of the above

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