Which type of motor is described as an AC motor that may trip when over?

• A. Induction motor
• B. Synchronous motor
• C. Universal motor
• D. Capacitor motor

Answer: (B)

The term "AC motor that may trip when over" aligns most closely with the characteristics of a synchronous motor. Synchronous motors operate at a constant speed that is synchronized with the frequency of the alternating current supply. These motors require precise control to maintain synchronization; if the load increases beyond a certain point, the motor may lose synchronization and trip to prevent damage.

This tripping behavior is critical because synchronous motors are often employed in applications where speed consistency is paramount. The tripping mechanism is a protective feature that helps prevent overheating and mechanical failure, ensuring that the motor does not operate outside its safe parameters.

In contrast, induction motors generally have a slip characteristic that allows them to adapt to varying loads without tripping, and they are less likely to lose synchronization. Universal motors can operate on both AC and DC but do not exhibit the same synchronization characteristics as synchronous motors. Capacitor motors, typically a type of split-phase motor, also manage loads in a different manner, often utilizing capacitors for improved starting torque but without the same risk of tripping due to load increases as seen in synchronous motors.