Prior to closing the breaker when...

Question 1 / 270705eccefa4bacbc34ba4d4818d

Question 1 of 270705eccefa4bacbc34ba4d4818d

Prior to closing the breaker when paralleling two AC generators, in terms of the oncoming machine frequency, what is the recommended practice?

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Question 1 of 27070

Prior to closing the breaker when paralleling two AC generators, in terms of the oncoming machine frequency, what is the recommended practice?

🔍 Key Concepts

• AC generator paralleling conditions: voltage, frequency, phase sequence, and phase angle • Effect of oncoming generator frequency on real power flow direction once the breaker is closed • What happens when oncoming machine frequency is slightly higher vs. slightly lower than the bus (line) frequency

💭 Think About

• When two AC generators are paralleled, how does a small difference in frequency between the oncoming machine and the bus affect the initial load sharing? • If the oncoming machine frequency is too low compared to the bus, which way will real power flow, and what operational problem could that cause? • Why might operators prefer the oncoming machine to begin by picking up load rather than being driven as a motor?

✅ Before You Answer

• Verify the four standard matching conditions before paralleling: voltage, frequency, phase sequence, and phase angle • Consider which option will cause the oncoming generator to take a small share of load rather than be motored by the bus • Eliminate any choice that ignores the actual line (bus) frequency condition at the moment of closing the breaker

Question 1 of 27070

Prior to closing the breaker when paralleling two AC generators, in terms of the oncoming machine frequency, what is the recommended practice?

slightly less than the line frequency

the same as the line frequency

slightly greater than the line frequency

exactly 60 Hz regardless of the line frequency

Question 1 / 270705eccefa4bacbc34ba4d4818d

Question 1 of 270705eccefa4bacbc34ba4d4818d

Prior to closing the breaker when paralleling two AC generators, in terms of the oncoming machine frequency, what is the recommended practice?

Back

Question 1 of 27070

Prior to closing the breaker when paralleling two AC generators, in terms of the oncoming machine frequency, what is the recommended practice?