no, varistors (what's in nearly all surge suppressors) either clamp the voltage at about twice what it should be, or fail shorted which they tend to do eventually (harmlessly blowing a fuse hopefully).
the issue is with plugging one thing, into another, into another and then into the wall, most outlet strips are cheap, they don't use proper sockets and often have/develop a significant resistance, which creates a hazard etc. Outlet strips also tell you not to plug one into the another, in this case it's the resistance problem and the risk that some consumers will run outlet strips all along a wall etc. pluged one into the other, which will eventually cause problems, because no one maintains outlet strips and few keep them clean and dry (it's easy to imagine someone in an older apartment having 10+ strips plugged into each other). And that's without pets, cat's for one have been known to urinate on outlets when mad, doesn't hurt an isolated cat but plays havoc with the outlet besides smelling terrible (likely the cats' motive). The reason newer houses have so many outlets is precisely to discourage the use of extension cords and prevent fires, an outlet strip isn't much better, and the fuse/breaker in any device only offers short circuit protection, a small overload or partial short in the load won't do it (unless you choose fuses/breakers very near the rated current, in which case you get nuisance blows/trips). note that when the connectors develop a higher resistance that the current actually decreases, but the energy dissipated in the connection produces excessive heat, which generally drives resistance higher until there's enough to start a fire or be noticed. the varistors are not the problem, note that computer power supplies and many peripherals include varistors for surge suppression and don't cause ups problems. on the other hand, you probably shouldn't use gas arrestors after an ups, when they conduct they short hard (gas plasma) and show a negative dynamic resistance which is a really good way to make something oscillate (not good for the ups) and definately will produce an excessive load for half a power cycle. gas arrestors are slower, but have unlimited short capacity, MOVs are faster but can absorb less energy typically. Thats why really good multistage arrestors use both, the MOVs conduct quickly and help limit the peak voltage, then the gas discharge tubes conduct and take most of the surge energy. either/both on the input side of the ups won't cause problems (and will help protect the ups), on the output side gas discharge tubes would be bad, varistors are fine at least until they short and blow a fuse, that's what fuses are for. there is a slight problem that some varistors start getting hot under normal conditions (failing but not yet shorted) which is why the manufacturers recomend adding a series thermal fuse thermally coupled to the varistor to disconect them in this case (and ideally the load depending on how things are wired). There are actually multistage devices that can protect low voltage lines (i.e. control lines on a transmitter tower) from a direct lightning strike assuming they have a good enough ground connection. of course it's likely to destroy the surge arrestor, which isn't cheap, but it protects far more expensive equipment when it self sacrifices. mad.scientist.at.large (a good madscientist) -- "The U.S. intelligence community concluded in a report made public in January that the Kremlin sought to disrupt the 2016 election and sway the race in Trump's favor." From "thehill.com". 30. Oct 2017 17:39 by michaelkintz...@gmail.com: > On Monday, 30 October 2017 21:01:35 GMT Dale wrote: >> While it is usually plugged into a surge strip already, >> the more the better. Actually, surge at the wall, UPS, then another >> surge strip that all my stuff plugs into. > > I'm sure I have read in some UPS manual that it should be plugged directly > into the mains socket and not via a surge protector. I assumed the manual > stated this because when the varistors in the surge protector start > conducting > excess current during a surge, this could start competing against the AVR in > the UPS, flipping the battery on/off and perhaps causing a race condition. I > haven't looked into it, but that's how I perceived it at the time. > > Of course we're talking of normal transients here, not a direct hit by a > lightning! LOL! > -- > Regards, > Mick
