Transformer neutral Grounding
Transformer neutral Grounding
(OP)
Under what conditions the promary and secondary neutrals of a Y Y power transformer can be connectec to a common ground bus that is bonded to main ground grid. I have recently come across this situation at a very old industrial SITE. Any comments, reference & suggestions aare most appreciated.
Morrison Dean
Morrison Dean






RE: Transformer neutral Grounding
IEEE C57.105 “The YG-YG should not be used except on 4-wire effectively grounded primaries as it merely carries the system ground through the transformation…” “If the connection is such as to permit this condition on the primary side, the transformer will supply part of the unbalanced phase-to-neutral loads and line-to-ground fault currents.”
IEEE C62.92.4 “If a primary-to-secondary fault developed within the transformer and the neutrals were not connected, the resistance of the return current path could be so high that not enough fault current would flow to enable the primary protective device to clear the fault. High voltage would then be impressed on the secondary for an extended period of time, posing a risk to humans, animals, and equipment.”
A hung jury, of sorts? Review the entire text of standards in making your determination.
RE: Transformer neutral Grounding
RE: Transformer neutral Grounding
I would like to add balanced voltages in the primary of the transformer to jbartos post, only as a clarification because "minimal zero sequence component passing through the transformer" implies balanced voltages