Cut through and identify useless sales people quickly. First demand
spec numbers. Every so often, one will provide those numbers. He is
the only one to talk to. A sales person who cannot provide numerical
specs up front is useless for any answers.

What is the THD of that generator or a UPS in battery backup? If he
doesn't know, then he will never provide useful numbers for protecting
that arc welder. THD is only one important criteria. But demanding
that number alone will weed out so many - most all - useless salesmen.

Biggest concern about a generator is not transients. Some generators
do not recover well from load changes. But then electronics inside an
arc welder should make such voltage variations irrelevant. Neither
transient suppressors nor a ferroreasonant transformer will solve that
problem since one is for voltages much higher and the other is for
voltage variations much smaller.

Len wrote:
The thing that irritates me most about a vaste majority of these so
called "sales people" is their fatal combination of 1) an enormous
lack of product-knowledge and reasonable client-orientation and
2) this inexplicable attitude consisting of selfindulgment and some
utterly misplaced feeling of superiority. In other words:
Arrogant Ignorance summa cum laude...
When I've got the time I like to play around with them sarcastically
just to see their pimpled faces become pale...