Busbar Rating

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Anonymous Poster	Busbar Rating 02/17/2010 11:44 PM
	Hai, i am working in oil and gas industry as electrical projects engineer. we have 415V panel in which bus bar rating is 50kA(i think this is Symmetrical rms value).We are doing Short circuit study for that network where symmetrical SC values for 3Φ fault are below 50kA.but assymmetrical values are about 61kA. Now my doubt is "Is the panel is ok or any problem.How to find assymmetrical rating of busbar".
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sidhu16 Commentator Join Date: Feb 2010 Location: India Posts: 92 Good Answers: 2	#1 Re: Gopi 02/18/2010 12:57 AM
	In all cases, symmetrical ratings are calculated and then this value is multiplied by suitable factors to get the asymmetrical value. You can search in Table No-8 of NEMA standard. This factor is as per X/R ratio at SC point.
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wareagle Guru Join Date: Jun 2008 Location: Alabama Posts: 1604 Good Answers: 63	#2 Re: Busbar Rating 02/18/2010 12:13 PM
	If the panel rating is above the symmetrical fault then it is usually adequate for the asymmetrical value. Verify this with the MFG.
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kvsridhar Guru Join Date: Sep 2009 Location: Temporarily at Ashburn, VA Posts: 2744 Good Answers: 164	#3 Re: Busbar Rating 02/18/2010 11:14 PM
	With a 50kA symmetrical fault level, as per IEC, the asymmetrical peak withstand should be 105kA peak. This usually lasts only a couple of cycles, so the key thing is that the busbars, supports etc must withstand this. Whenever i had to do these withstand tests at the test lab here, i used to apply 5 cycles with the asymmetrical peak of 105kA, followed by a 1 sec test without any asymmetry. This way, you can find out whether any failure is due to dynamic effect or thermal effect. __________________ Nothing worthwhile can ever be taught, it can only be learnt.
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You might be interested in: Busbars and Busways, Flat Panel Displays, Analog Panel Meters

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