Which of the listed conditions could cause a...

Question 1 / 270705eccefa3bacbc34ba4d4806b

Question 1 of 270705eccefa3bacbc34ba4d4806b

Which of the listed conditions could cause a recently overhauled DC motor to have excessively hot windings and sparking at the brushes?

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Question 1 of 27070

Which of the listed conditions could cause a recently overhauled DC motor to have excessively hot windings and sparking at the brushes?

🔍 Key Concepts

• Commutation in DC motors and the role of interpoles (commutating poles) • Relationship between brush sparking, armature reaction, and field polarity • Effects of field current (series vs shunt) on motor operation and heating

💭 Think About

• Which component or condition most directly affects how current transfers between the commutator segments and brushes during rotation? • Among the options, which one would most likely disturb the neutral plane and worsen armature reaction, leading to sparking? • Which options are more likely to cause loss of torque or speed changes, rather than severe brush sparking and hot windings?

✅ Before You Answer

• Identify which choice directly relates to polarity of commutating (inter) poles and its effect on commutation. • Consider which field current change (high or low) would more likely strengthen the main field and tend to reduce, not increase, sparking. • Ask whether humidity alone, without an electrical fault, would normally cause both very hot windings and heavy brush sparking.

Question 1 of 27070

Which of the listed conditions could cause a recently overhauled DC motor to have excessively hot windings and sparking at the brushes?

Reversed interpole polarity

Low series field current

High shunt field current

Excessive humidity

Question 1 / 270705eccefa3bacbc34ba4d4806b

Question 1 of 270705eccefa3bacbc34ba4d4806b

Which of the listed conditions could cause a recently overhauled DC motor to have excessively hot windings and sparking at the brushes?

Back

Question 1 of 27070

Which of the listed conditions could cause a recently overhauled DC motor to have excessively hot windings and sparking at the brushes?