The material for commutator brushes is generally_______________?
The material for commutator brushes is generally_______________?
A. mica
B. copper
C. cast iron
D. carbon
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In case of a 4-pole D.C. generator provided with a two layer lap winding with sixteen coils, the pole pitch will be__________________?
In case of a 4-pole D.C. generator provided with a two layer lap winding with sixteen coils, the pole pitch will be__________________?A. 4
B. 8
C. 16
D. 32In over compounded generator, full load terminal voltage is______________?
In over compounded generator, full load terminal voltage is______________?A. almost zero
B. less than no load terminal voltage
C. more than no load terminal voltage
D. equal to no-load terminal voltageFor a D.C. machines laboratory following type of D.C. supply will be suitable___________?
For a D.C. machines laboratory following type of D.C. supply will be suitable___________?A. rotary converter
B. mercury are rectifier
C. induction motor D.C. generator set
D. synchronous motor D.C. generator setArmature reaction in a generator results in_____________?
Armature reaction in a generator results in_____________?A. demagnetisation of leading pole tip and magnetisation of trailing pole tip
B. demagnetisation of trailing pole tip and magnetisation of leading pole tip
C. damagnetising the center of all poles
D. magnetising the center of all polesArmature reaction of an unsaturated D.C. machine is_____________?
Armature reaction of an unsaturated D.C. machine is_____________?A. crossmagnetising
B. demagnetising
C. magnetising
D. none of aboveThe function of pole shoes in the case of D.C. machine is______________?
The function of pole shoes in the case of D.C. machine is______________?A. to reduce the reluctance of the mag¬netic path
B. to spread out the flux to achieve uniform flux density
C. to support the field coil
D. to discharge all the above functions