Variac/Powerstat overload capacity

The latest Superior Powerstat catalog (PVT696) contains a graph showing the
overload capacity for all Powerstat models. Regardless of brand, all
variable transformers have a large thermal mass, and and are wound with
wire that can handle many times the nameplate rating. Rather severe
overloads can be tolerated, as long as a cooldown interval is provided
between overload cycles.  Make sure that brushes, commutators and slip
rings are clean and bright to avoid localized overheating due to high
resistance at the brush contact points.

Essentially, the (interpolated) datapoints of interest to coilers are:

On time        Overload  Cooldown
30 s    	   400%      8 minutes
1 min          350%      12 minutes
2 min          300%      17 minutes
5 min          250%      30 minutes
10 min         225%      40 minutes