[RE-wrenches] transformers with PV

[Kirk Herander]

Hello transformer gurus,

 

I am in the middle of a good sized PV job and we need to use a 75 kva
480/208 3 phase transformer (standard delta to wye) to connect the 208 3
phase output to the building service 480. So the transformer/PV constitutes
a separately derived system. The OEM's transformer wiring diagram is vague
but is prewired for H1,2,3 inputs and X0 - x4 outputs at 208. I think I got
this right: the 480 primary feeder neutral is not used, primary gnd goes to
xformer equipment gnd, secondary 208 neutral is created on secondary X0,
secondary X0 is bonded to equipment gnd, and the 208 gnd originates at the
equipment gnd terminal. And a GEC must travel from xformer gnd terminal to a
code-approved grounding electrode (rod, building steel, etc).

I am gleaning some of this from a Mike Holt article, just want to make sure
I'm not missing anything obvious. Thanks.

 

Kirk Herander

VT Solar, LLC

dba Vermont Solar Engineering

NABCEPTM Certified installer Charter Member

NYSERDA-eligible Installer

VT RE Incentive Program Partner

802.863.1202

 

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