Is hi pot test destructive test shall not be repeated several time? And how much the injection level for the 3 rd time for 33 kv swgr?

I think synchronizing will never  take place due to difference in voltage.

For 33 KV system  high pot voltage will be ( 33X2)+1 = 67 KV for New Machine. But for 3 year old Machine will be arround 49 KV. But for oll machine( More than 5 Years) it will be arround 37 KV.

But for 3 years/ old Machine it should not be repeated, otherwise may lead insulation failure