🔍 Key Concepts
• Basic starting circuit for a motor generator: power supply, protection devices (fuses/breakers), control circuit, and the motor itself
• Common electrical faults that prevent a motor from starting (open circuits vs short circuits vs mechanical jam)
• How a single fault vs multiple possible faults would affect your choice among A, B, C, and D
💭 Think About
• For each option (A, B, C), ask: Would this prevent the motor generator from starting when the start button is pressed? Think about the current path from the source to the motor.
• Consider whether each listed condition is a realistic and common cause of a failure-to-start, not a running problem.
• Ask yourself: If more than one of these could independently cause a no-start condition, what does that suggest about option D?
✅ Before You Answer
• Trace the current path: from the power source, through the protective device, start switch, field/armature circuits, to the motor.
• Distinguish between faults that cause no current flow (open circuit, blown fuse, tripped breaker, open rheostat, broken connection) and those that cause poor commutation (defective brushes).
• Before choosing, verify whether each of A, B, and C describes a condition that could reasonably result in no start when the button is pressed.