NEIEP Mechanics Practice Exam

What color is indicative of a good commutator with effective commutation?

1. Black

2. Chocolate

3. Silver

4. Grey

The correct answer is: Chocolate

A chocolate-colored commutator indicates effective commutation and is often a sign that it is in good condition. This color typically results from a combination of the materials used in the commutator segment and the thermal effects from operation. The chocolate hue suggests that the commutator has not been excessively heated, which can lead to burning or other forms of degradation. A well-maintained commutator will show minimal wear, with a smooth surface that facilitates effective electrical contact with the brushes, enhancing the overall performance of the motor or generator. Choosing other colors, such as black or grey, may indicate improper commutation or excessive wear. Black can signify a buildup of carbon or overheating, while grey might represent wear or oxidation. Silver is less common and doesn't usually indicate a standard condition for commutation.