Odd Overloaded NST Effect

	I have 6 15Kv-at-30mA transformers connected together for a monsterous output
of 180mA; at least theoretically.  The current from my mains supply goes
through my variac first, which has a built-in voltmeter.  When I apply
power to my transformer bank, I notice the voltmeter goes CRAZY, swaying
back and forth between about 90 and 145 volts.  I heard someone recently
talking about the voltage field collapsing as the current field goes too
high in an NST, or something wacky like that.  The last time I asked how
many NSTs could be paralleled successfully however, the only response I got
was "there shouldn't be any limit".  So, what do you think is the deal?

	-- Ryan Ries