Which of the following is NOT a common type of motor protection device?

Transformers are not considered a common type of motor protection device because their primary purpose is to change the voltage of electricity in a circuit, either stepping it up or stepping it down. In contrast, circuit breakers, overload relays, and fuses are all specifically designed to protect motors from electrical issues.

Circuit breakers provide an automatic interruption of the circuit in case of overload or short circuit conditions, thereby protecting the motor from damage. Overload relays detect excessive current flowing through the motor and disconnect the power to prevent overheating. Fuses serve a similar function by melting under excess current conditions, breaking the circuit and preventing damage to the motor. These components are essential in safeguarding motors from electrical faults, ensuring safe operation and longevity.