# Load sharing Parallel generators



## PE blues (Mar 11, 2013)

Does any one have good reference material on parallel generators and different modes of operation? I did google search, but I couldn't find one document that covers both isochronous and droop mode operations.

I would appreciate if you can share any material you may have.


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## jcbabb (Mar 13, 2013)

http://seniordesign.engr.uidaho.edu/2008_2009/oltc/7400DB0701.pdf

I've got this in my binder for use on the exam.


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## jcbabb (Mar 13, 2013)

I should also state that I have no idea what droop mode or isochronous mean, and as such would hope that they are not on the exam. I have never heard of either before this post.

Hopefully the PDF I referenced is still helpful to you in some way.


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## PE blues (Mar 14, 2013)

From what i have found on the internet.

Isochronous mode: generators try to maintain constant frequency (speed). So the generator that is designated as isochronous control sees change in system frequency and adjusts power output to bring the frequency up

Droop mode: Generators wait for the frequency drop, and all the generators are adjusted based on droop setting to bring the frequency up

Essentially one is immediate control, other is not.

thank you for the pdf.


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## PE blues (Mar 14, 2013)

forgot to mention, those modes are for generator parallel operation, not transformers.


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## bobadrew (Mar 14, 2013)

The Camara book has some info on this topic. I don't have my book any more but someone else might be able to share that.


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## power62 (Mar 14, 2013)

Elect Machinery Fundamentals by Steve Chapman has really good infomation on this topic. That's one of the very few places that discusses this topic.


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## Zack J. (Mar 15, 2013)

power62 said:


> Elect Machinery Fundamentals by Steve Chapman has really good infomation on this topic. That's one of the very few places that discusses this topic.




Where in the Electrical Machinery Fundamentals is this topic? I didn't see it when I was going through generators.


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## jcbabb (Mar 15, 2013)

Do any of you believe that this is a topic that will be covered on the exam?


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## Ivory (Mar 15, 2013)

The spec has it listed in section IV.

B. Power System Performance

2. Load sharing: parallel generators


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## power62 (Mar 16, 2013)

Topic is discussed in Chapter 5 of the book (Elect Mach Fundamentals by S Chapman 4th edition).


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## nasir (Mar 30, 2013)

Last Exam there was generator and UPS questions....Especially how UPS is connected in a system... There was also a transfer switch between Generator and Panel....Just remember interconnection schemes and how to size them... Paralleling questions were similar to problems in the NCEES...

Selective coordinations were also there... In balance currents and power calculation was also there.

Good luck.


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