100 A
200 A
machine the current per brush arm should not be more than A. 100 A B. 200 A C. 300 A
400 A
Answer is Wrong!
Answer is Right!
The correct answer is A. 100 A.
The current per brush arm should not be more than 100 A. This is because the brushes are the only contact between the rotating commutator and the stationary windings of the DC machine. If the current is too high, the brushes will wear out quickly and may cause arcing, which can damage the machine.
Option B is incorrect because 200 A is too high a current for the brushes to handle. Option C is incorrect because 300 A is also too high a current for the brushes to handle. Option D is incorrect because 400 A is even higher than 300 A, and therefore it is also too high a current for the brushes to handle.