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Guest	pewe 05/08/2008 10:47 PM
	hi gang, i have 208/120 volt 3 phase in building, need to step up with 208/120 volt to 480 volt 3 phase, 3 wire 75 kva transformer, should i ground the center point of the 208 to ground? what could happen i don't ground it? thanks
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sachin patil Participant Join Date: May 2008 Posts: 2	#1 Re: pewe 05/09/2008 1:25 AM
	Dear sir, It is not necessary to ground the primary side(208)because the connection of transformer is DELTA - STAR in such case secondary side (480) need to solidlyground(earthed) for neutral purpose not primary(208)
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Sparkstation Guru Join Date: Nov 2007 Location: Christchurch, (The Garden City), South Island, New Zealand Posts: 2821 Good Answers: 125	#2 Re: pewe 05/09/2008 1:41 AM
	Hello Guest, It is not the "Centre-point" of the windings, but a "Star Point", almost surely. If it is a "Star Point", you do not need to ground it, but keep clear of it, as under certain conditions, it may rise above ground potential. We are trying to analyse your situation via CR4 remotely, and you need to be very careful with what you are doing. A proper description of the transformer would assist. If you intend to run another transformer in parallel with the proposed one, ensure that the phase angles of the transformers are identical, or large circulating currents will result, and may destroy equipment. Kind Regards.... __________________ The number of inventions increases faster than the need for them at the time - SparkY

hastingselectric Power-User Join Date: Oct 2007 Location: Hartwell Georgia N34* 56.770 / W83* 35.431 Posts: 227 Good Answers: 1	#3 Re: pewe 05/11/2008 11:43 AM
	No, you don't need to ground the primary side. Size your breaker correctly, bond all metal parts back to the distribution ground and use a 208/480 three phase transformer. Better yet, utilize a local contractor for the installation. Good luck, James __________________ " adapt, improvise, overcome "

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