Question 229Electricity & Electronics - 1st Asst/Chief

The correct answer is B) sparking of the brushes. Insufficient brush pressure on a DC motor can cause the brushes to lose contact with the commutator, leading to sparking. This sparking occurs because the commutator segments are not making proper electrical contact with the brushes, causing an uneven and inconsistent flow of current. This can lead to accelerated wear of the brushes and commutator, and potentially damage the motor over time. The other answer choices are incorrect. Insufficient brush pressure does not directly cause excess residual magnetism (A), water vapor absorption (C), or generator overload (D). These issues are typically caused by other factors related to the motor's design, maintenance, or operating conditions.