Grounding Trafo deraing factor

[RRaghunath]

The grounding transformer is rated generally for a duration of 10sec.

If IEEE32 is referred, the thermal to continuous current ratio for the transformer will be 10 (approx). Whereas, the same would be more than 33 (approx) if IEEE 62.92.2 is followed.

Obviously, I am missing some thing. Can some one help.

Thanks in anticipation.