🔍 Key Concepts

• Function of protective relays in generator circuits • Difference between reverse current and reverse power conditions • What happens to a generator when the prime mover fails but it remains connected to the bus

💭 Think About

• Think about what physically happens to an AC generator if the driving engine or turbine loses power while the generator is still synchronized to the switchboard: does it start taking power or delivering power? • Consider which device is designed to sense the direction of real power flow in an AC system rather than just current magnitude and direction. • Ask yourself which of these choices is typically associated with DC systems versus AC alternators on shipboard power plants.

✅ Before You Answer

• Verify which device specifically monitors power direction (kW), not just current. • Check which relay is commonly used for AC alternators to prevent the machine from becoming a motor and overloading the prime mover. • Eliminate options that are more about mechanical isolation or energy storage rather than automatic protection based on power flow.