andrewpreece wrote:

Perhaps apparatus
that is essentially a calorimeter would work ( i.e. pick off some of the
load power with a series resistor which sits inside a calorimeter: wait five
minutes and measure the temperature rise ).


I think this is very cunning (also suggested by Lee) - it may well be
the way to do it. The only thing that concerns me is what kind of big
power resistor to use and guarantee that it will remain sufficiently ohmic.


--
Grunff