After a minute running, dryer trips main breaker outside the house, but no internal breakers
It seems to me, after reading all the stuff in your first question and on here that the problem is inside your cloths dryer. There is a good chance that some part of the heater coil is becoming shorted out and causing huge amounts of current to flow when the coil becomes hot. 

The probable reason that it is the main breaker that trips is due to that breaker being the most sensitive to the sudden current surge short that occurs in the dryer. It may be an indication that that main breaker needs replacement but before even going down that road it is time to unplug the dryer and do a through investigation of its innards, particularly its heater unit and the wiring thereof.