What should be the frequency of the incoming...

Question 1 / 270705eccefa4bacbc34ba4d4818a

Question 1 of 270705eccefa4bacbc34ba4d4818a

What should be the frequency of the incoming machine when paralleling two AC generators immediately prior to closing its breaker?

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Question 1 of 27070

What should be the frequency of the incoming machine when paralleling two AC generators immediately prior to closing its breaker?

🔍 Key Concepts

• Synchronous speed and frequency relationship when connecting AC generators in parallel • Effects of large frequency differences on power flow and mechanical stress • Why operators prefer an incoming generator to "creep" in one direction on a synchroscope before closing the breaker

💭 Think About

• Before closing the breaker, do you want the incoming generator to be running noticeably faster, noticeably slower, or just a little different from the bus so you can control the point of synchronization? • If the incoming machine’s frequency is too high or too low compared to the bus, what happens to torque and power flow the instant the breaker closes? • On a synchroscope, do operators usually prefer the pointer to approach the in-phase mark slowly or to be stationary, and in which direction should it be moving just before closing?

✅ Before You Answer

• Make sure you understand that large frequency differences at closing can severely stress the generator and prime mover. • Think about normal shipboard paralleling procedure: do engineers aim for a slow, controlled "roll" of the synchroscope, or a rapid swing? • Verify which is desirable: the incoming machine frequency being slightly higher, slightly lower, or exactly equal just before you close the breaker.

Question 1 of 27070

What should be the frequency of the incoming machine when paralleling two AC generators immediately prior to closing its breaker?

at least 5 Hz higher than the bus frequency

exactly equal to the bus frequency

slightly greater than the bus frequency

slightly less than the bus frequency

Question 1 / 270705eccefa4bacbc34ba4d4818a

Question 1 of 270705eccefa4bacbc34ba4d4818a

What should be the frequency of the incoming machine when paralleling two AC generators immediately prior to closing its breaker?

Back

Question 1 of 27070

What should be the frequency of the incoming machine when paralleling two AC generators immediately prior to closing its breaker?