John Gray wrote:I have yet to see any scientific paper which tests the efficacy or the requirement for surge protectors in countries which don't have significant lightning problems and which have well-regulated power distribution systems, like in the UK.
Consequently I consider them rather like snake-oil and FUD - but would be pleased to be proved wrong!
Come on down to Florida, the Lightning Capital of the World, then you'll think differently!
I was inside a contract manufacturing facility where I was working back in my test engineering days when lightning hit the main power input panel on the outside of the building. We had, for the time, state of the art customized power protection installed that included high voltage gas discharge tubes, high-capacity iron core inductors (big rods of iron with very heavy wire wrapped around several times), and high capacity MOVs. The MOVs blew out totally, creating a very loud bang and lots of smoke, and most of the breakers tripped, but the equipment, and especially my test equipment, all survived due to the surge pulse rise time being limited by the iron core inductors and the remaining energy being shorted first by the MOVs (fast reaction time) then by the gas discharge (slow reaction time).
I've seen first hand what happens without those mitigation strategies in place!
Very cheap, and early surge protectors relied on MOVs across the mains, but they either degrade or are completely destroyed depending on the energy being shunted. However, there is no reliable test to tell what level of degradation has occurred, other than hitting them with a high-energy pulse with a voltage over their breakdown limit to see if they work. This can sometimes be a destructive test, and certainly degrades the operational capacity, so we mainly tested that the part wasn't shorted out when we tested them at all.
Gas discharge was the gold standard at the time for high tolerance circuitry, such as the telephone network, which is very robust compared to modern electronics. It's slow reaction time wasn't a problem for the phone company as they were just protecting their network and didn't worry about what the customer had connected to it, thus lots of early computers were fried by surges coming down the phone line into the modems instead of surges through the power lines.
New technologies have come along, but I'm not up to speed on the latest, but this is my two cents worth on surge protection in the prehistoric eras.
