Electrician Red Seal · Question
An electrician is inspecting the brushes on a DC motor and notices severe arcing and pitting on the commutator segments. What is the most likely cause of this issue?
Weak brush springs lead to insufficient pressure between the brushes and the commutator, causing intermittent contact, sparking, and burning (pitting) of the co
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Question: An electrician is inspecting the brushes on a DC motor and notices severe arcing and pitting on the commutator segments. What is the most likely cause of this issue?
Answer options:
- The brushes are made of a material that is too hard. ✅ The brush springs are too weak, causing poor contact.
- The motor is running at a speed too low for its application.
- The motor is underloaded, reducing brush friction.
Correct answer: The brush springs are too weak, causing poor contact.
Explanation: Weak brush springs lead to insufficient pressure between the brushes and the commutator, causing intermittent contact, sparking, and burning (pitting) of the commutator segments. Hard brush material or an underloaded motor are less likely to cause severe arcing and pitting. Low speed wouldn't inherently cause this unless it led to unstable operation.
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