HV Earthing

What is the recommended standard, connecting the arrestor earth and the transformer tank earths together or seperate?

[topgroove]

here at national grid on a wye system there bonded together on a delta system they're seperate

[Squizzy]

Ours are always together, the surgies are mounted on the TX and connected to earth via the earth stud on the transformer tank. (all our HV is in delta)

[thrasher]

If it's a tank mounted transformer arrester then we ground thru the stud on the txf to the txf ground loop. If it's an arrester on an OCR or x-arm mounted then it's grounded independent of other equipment. Our system is all grounded wye.

[topgroove]

on ungrounded delta's the engeneers have found that current from a lightning strike can enter the customer mains and do a lot of damage in a blink of the eye. that's why we keep them separate. On a multi grounded wye the arrestors are bonded together with the stytem nuetral.