Question 1 of 270705eccefa4bacbc34ba4d481c9

What will happen when a loss of field excitation to an AC generator occurs while operating in parallel?

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Question 1 of 27070
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What will happen when a loss of field excitation to an AC generator occurs while operating in parallel?

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🔍 Key Concepts

• Loss of field excitation on a synchronous AC generator (alternator) • Behavior of a synchronous generator operating in parallel with others • Relationship between excitation, reactive power (kVAR), and prime mover speed/governor

💭 Think About

• Think about what provides the generator’s magnetic field when it is synchronized and sharing load. What happens to its ability to produce voltage and reactive power if that field disappears? • In a parallel setup, when one generator’s excitation is lost, how does the system (bus) react? Does that machine tend to pick up more load, drop its load, or change speed? • Consider what would make a generator accelerate or decelerate when its electrical load changes suddenly. How would losing most or all of its electrical load affect the prime mover speed?

✅ Before You Answer

• Verify what a synchronous generator becomes (in electrical behavior) when its DC field is lost but it remains mechanically driven and connected to the bus. • Check whether speed droop in the governor directly responds to changes in electrical load or to changes in frequency/speed, and how that interacts with losing excitation. • Confirm whether field flashover and smoking are typical immediate effects of loss of excitation, or whether another mechanical/electrical consequence is more likely in a healthy, protected system.