In a D.C. machine, the value of peripheral speed should not, normally, exceed___________?
(A) 10 m/s
(B) 20 m/s
(C) 30 m/s
(D) 40 m/s
The weight of copper of both armature and field windings decreases with __________ in number of poles?
(A) increase
(B) decrease
(C) either of the above
(D) none of the above
A practical formula for determining the thickness of insulation between low voltage and high voltage windings is__________________?
(A) 1 + 0.2 kVmm
(B) 2 + 0.5 kVmm
(C) 4 + 0.7 kV mm
(D) 5 + 0.9 kV mm
The surge phenomenon is particularly important in case of_______________?
(A) low voltage transformers
(B) medium voltage transformers
(C) high voltage transformers
(D) any of the above
The insulation between windings and grounded core and the insulation between the windings of the same phase is called__________________?
(A) minor insulation
(B) major insulation
(C) either of the above
(D) none of the above
____________ is the common method of applying brushes to the commntator?
(A) Radial
(B) Trailing
(C) Reaction
(D) All of the above
___________ brushes are fragile and cause excessive wear of commutator?
(A) Natural graphite
(B) Hard carbon
(C) Electro graphitic
(D) Metal graphite
The laminations of the armature of a D.C. machine are usually ___________ thick?
(A) 0.1 to 0.2 mm
(B) 0.2 to 0.3 mm
(C) 0.3 to 0.4 mm
(D) 0.4 to 0.5 mm
The cylindrical windings using circular conductors are used for current rating of____________?
(A) upto 20 A
(B) upto 40 A
(C) upto 60 A
(D) upto 80 A
Which of the following in an application of D.C. motors?
(A) Traction
(B) Drives for process industry
(C) Battery driven vehicles
(D) Automatic control
(D) All of the above