Excitation Current of AC Generator ?

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Anonymous Poster	Excitation Current of AC Generator ? 09/20/2010 7:22 AM
	Is it really difficult to understand excitation current required for AC generator for a enthusiastic mechanical engineer? Can some expert guide in this regard. Let us be specific, I wanted to learn what should be rating of a excitation cubical for 50 MVA generator operating at 200 RPM. Please assume typical electrical data if any other required.
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JRaef Guru Join Date: Sep 2006 Location: California, USA, where the Godless live next door to God. Posts: 4665 Good Answers: 804	#1 Re: Excitation Current of AC Generator ? 09/20/2010 12:56 PM
	No such thing as "typical" unfortunately. You don't say what kind of "generator" but I suppose we can ASS-U-Me synchronous by virtue of the 200RPM? Still, self excited or externally excited? Brushless? What do you mean by "cubical"? __________________ All I every really wanted to be, was... A LUMBERJACK!.
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Le_Noble Power-User Join Date: Feb 2008 Location: Beirut Lebanon Posts: 197 Good Answers: 8	#2 In reply to #1 Re: Excitation Current of AC Generator ? 09/21/2010 3:08 AM
	I guess he means "cubicle". Guest, an excitation cubicle for a 50 MW alternator could include PT's for AC voltage sensing, a DC power converter, CT's for droop and PF control, AVR to regulate AC voltage, electronic for parallel control and much more..... does it still look complicated for a mechanical engineer? __________________ dont say it, write it
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Anonymous Poster	#4 In reply to #2 Re: Excitation Current of AC Generator ? 09/21/2010 3:25 AM
	not really, please proceed further to calculate (dc)field current & voltage rating of excitation cubicle.
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Anonymous Poster	#3 In reply to #1 Re: Excitation Current of AC Generator ? 09/21/2010 3:21 AM
	Regret for typographical error. It is cubicle (excitation panel). Other related information is : Synchronous generator 50 MVA, externally excited, 13.8 Kv, 50 Hz, Cos phi 0.9.RPM 200, How to calculate required (DC) field current and voltage rating of excitation panel ?
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Le_Noble Power-User Join Date: Feb 2008 Location: Beirut Lebanon Posts: 197 Good Answers: 8	#5 In reply to #3 Re: Excitation Current of AC Generator ? 09/21/2010 3:47 AM
	Nothing to calculate, you have to check with the manufacturer.... Or you can inject a small DC voltage and check the output voltage ( you need PT's) and than increase this DC till you reach 13.8 KV, this is the MINIMUM DC voltage you need for the excitation at no load , at full load it is much higher, 4 to 5 times, for the current you can measure the resistance of the field coil and calculate the required current as per DC voltage needed __________________ dont say it, write it
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Anonymous Poster (2); JRaef (1); Le_Noble (2)

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