Grounding transformer to enclosure
Grounding transformer to enclosure
(OP)
A manufacturer of 345 kV circuit breaker provided a 7.5 kVA transformer 480-240/120V for with a neutral grounded on the control cabinet. This cabinet is bolted to the metallic part of the circuit breaker witch is grounded to the substation ground grid at the base.
The local utility engineer is challenging the transformer grounding to the enclosure instead a direct grounding conductor connected to the substation ground grid.
I have a hard time finding any code violation or no compliance to the NEC, IEEE, NESC etc. regarding the grounding proposed by the manufacturer.
Please advise if there is any objectionable grounding in this arrangement.
Thanks
The local utility engineer is challenging the transformer grounding to the enclosure instead a direct grounding conductor connected to the substation ground grid.
I have a hard time finding any code violation or no compliance to the NEC, IEEE, NESC etc. regarding the grounding proposed by the manufacturer.
Please advise if there is any objectionable grounding in this arrangement.
Thanks






RE: Grounding transformer to enclosure
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I don't see a problem with this.
RE: Grounding transformer to enclosure
RE: Grounding transformer to enclosure
RE: Grounding transformer to enclosure
I think the concern may be the reliability over time of using the enclosure as a ground path, especially on a high voltage breaker. As corrosion sets in, the ground path through the bolts and metal-to-metal interfaces could increase in resistance.
I do not think it is an NEC issue, but just question of what is the "best practice".
RE: Grounding transformer to enclosure