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jinxnao
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Generator Load and Frequency

03/23/2009 9:13 AM

Hello , for example i have a isolated synchronous generator and i turn off governor and AVR , i have some load(1 unit for example and a light one ) and i suddenly increase the load,so if all controls are off and i have an imbalance of load versus generation, so as far as i know the speed will decline ok?

i wonder why the speed decline when spoken scientifically?

Also i wonder how can be such an imbalance? i have 1 unit generation but my load is for example 1.2 unit??? does the decline of speed means 0,2 unit load?? of course not but how can it be?

in short explain to me pls, what happens till the governor and AVR senses the need to the power from the shaft....the generator will feed 1,2 unit power or not??

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sb
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#1

Re: Generator Load and Frequency

03/23/2009 1:21 PM

Just a simple question. if you don't mind it, I am feeling inquisitive

Why all these questions from you ?

Most of these are basic operations , in fact all are. Answer is simple and the question that you have asked is already reflected in one of your previous queries. Your profile does not give any detail. Neither do the questions asked earlier.

But why these questions ? answer is simple. But ..

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jinxnao
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#2

Re: Generator Load and Frequency

03/23/2009 7:56 PM

Yes it is a really simple question but i bet you dont know why....

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sb
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#3
In reply to #2

Re: Generator Load and Frequency

03/23/2009 9:59 PM

With due regards, look at my profile and my threads on much more interesting subjects.

And no I don't need childish challenges. Past that age. My children (about 10+) do it. But for them too I give hints and not the answer.

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SHOCKISCAN
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#4

Re: Generator Load and Frequency

03/24/2009 12:01 PM

My guess is:

P = EI

If E decreases due to load increase (I^), then P decreases.

If P decreases then the machine rotational speed declines due to the magnitude of the mechanical load applied not having changed/decreased.

Hence: Until the AVR catches up and increases the excitation enough to return E to the synchronous value required, rotational speed declines and you suffer loss of frequency.
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Anonymous Poster
#5

Re: Generator Load and Frequency

03/24/2009 4:46 PM

Jinxnao,

Look at the way you have phrased your question. If you have switched off the AVR and the governor the prime mover power has ceased and the field for generation also.

Do you mean that you have (hypothetically) fixed the setting of these controls so they do not vary? i.e. manually set throttle and field current or are you only asking about the instantaneous behaviour of the machine before the automatic controls react?
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jinxnao
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#6
In reply to #5

Re: Generator Load and Frequency

03/25/2009 11:13 AM

of course i mean they are unchanged and we just increase the load.So for a moment or more long time we have an unbalance here, as we know the shaft gets slower but if it gets slower its E will decrease and but I increases so what is the last power equation as long as we dont change fuel and exciting....

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Anonymous Poster
#7

Re: Generator Load and Frequency

03/30/2009 4:04 PM

Good day

you need to check exactilly the rottating diode of the lowest load generator
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