A. brushes should be of proper grade and size
B. brushes should smoothly run in the holders
C. smooth, concentric commutator properly undercut
D. all of the above
Correct Answer: all of the above ✔
Last Updated: July 05, 2018
Related MCQs
- In a D.C. machine stray loss is the sum of__________?
- The armature core of a D.C. generator is usually made of__________?
- In any rotating machine that part which houses the conductors and in which e.m.f. induced is to be utilized is called__________?
- The e.m.f. generated by a shunt wound D.C. generator isE. Now while pole flux remains constant, if the speed of the generator is doubled, the e.m.f. generated will be__________?
- A D.C. generator can be considered as__________?
- The voltage drop for which of the following types of brush can be expected to be least ?
- Two generators A and B have 6-poles each. Generator A has wave wound armature while generator B has lap wound armature. The ratio of the induced e.m.f. is generator A and B will be__________?
- Number of tappings for each equalizer ring is equal to__________?
- In D.C. generators, lap winding is used for__________?
- In a D.C. generator the ripples in the direct e.m.f. generated are reduced by__________?
- The rapid wear of brushes takes place due to__________?
- Which of the following components of a D.C, generator plays vital role for providing direct current of a D.C. generator ?
- Compensating windings are used in D.C. generators__________?
- The following constitute short-circuit in the armature winding.
- The number of brushes in a commutator depends on__________?
- Magnetic field in a D.C. generator is produced by__________?
- To avoid formation of grooves in the commutator of a D.C. machine?
- The demagnetising component of armature reaction in a D.C. generator__________?
- A cumulatively compounded long shunt generator when operating as a motor would be__________?
- Armature coil is short circuited by brushes when it lies__________?
- Which of the following statement about D.C. generators is false ?
- To achieve sparkless commutation brushes of a D.C. generator are rockedm ahead so as to bring them?
- A D.C. welding generator has__________?
- In a D.C. generator the critical resistance refers to the resistance of__________?
- The e.m.f. induced in the armature of a shunt generator is 600 V. The armature resistance is 0.1 ohm. If the armature current is 200 A, the terminal voltage will be__________?
- In the case of lap winding resultant pitch is__________?
- The function of pole shoes in the case of D.C. machine is__________?
- Flashing the field of D.C. generator means:__________?
- For a D.C. machines laboratory following type of D.C. supply will be suitable__________?
- In case of D.C. machine winding, number of commutator segments is equal to__________?
- Welding generator will have__________?
- Equilizer rings are required in case armature is__________?
- Eddy currents are induced in the pole shoes of a D.C. machine due to__________?
- D.C. generators are connected to the busbars or disconnected from them only under the floating condition__________?
- Armature reaction of an unsaturated D.C. machine is__________?
- If brushes of a D.C. generator are moved in order to bring these brushes in magnetic neutral axis, there will be__________?
- In D.C. generators, the brushes on commutator remain in contact with conductors which__________?
- The insulating material used between the commutator segments is normally__________?
- The material for commutator brushes is generally__________?
- In case of a 4-pole D.C. generator provided with a two layer lap winding with sixteen coils, the pole pitch will be__________?
- If B is the flux density, I the length of conductor and v the velocity of conductor, then induced e.m.f. is given by__________?
- If a D.C. generator fails to build up the probable cause could not be__________?
- Brushes of D.C. machines are made of_________?
- In D.C. generators, current to the external circuit from armature is given through__________?
- Iron losses in a D.C. machine are independent of variations in__________?
- Iron losses in a D.C. machine are independent of variations in__________?
- The armature of D.C. generator is laminated to__________?
- Laminations of core are generally made of__________?
- Which of the following could be lamina-proximately the thickness of laminations of a D.C. machine ?
- The commutator segments are connected to the armature conductors by means of__________?
- The resistance of armature winding depends on