chaining surge protector->ups->surge protector?

[Conroy9]

All the UPS manufacturers seem to advise against this, does anyone know why?

It seems to me that if you attach a surge protector to the output of a UPS, the UPS would handle all of the voltage regulation so that the surge protection would never be used..

And if you attach a UPS to the output of a surge protector, the surge protector would just prevent surges from getting to the UPS in the first place.

Isn't this just simple physics, or am I missing something?

Conroy

 

[RSMemphis]

The UPS normally is a surge surpressor in any case.

The battery of the UPS acts like a huge capacitor, as well. Flattens out the current pretty neatly.

 

[Conroy9]

so that would imply that it's useless, but not that it's harmful?

 

[kpb]

I beleive the reason that they recommend that is that the outlets on the UPS and Power strips aren't designed to handle the large amounts of power that multiple devices like that would draw. Its the same reason that you shouldn't use a surge protector off a surge protector. Basically the big risk is that you can draw enough current threw the wires to over heat the wires and melt the insulation and short out or start a fire.

 

[ScottMac]

Assuming you're talking about a Standby UPS (like most consumer-grade UPSs), the issue is that each of those device distort (to some degree) the electrical waveform (or, in some cases, cause phase distortion between the Voltage & curent).

By cascading passive/active devices, you may be amplifying the distortion sufficiently to destabilize the attached equipment or cause it's early failure.

I've also heard discussion that by cascading power protection devices (mostly surge strips), you are putting some devices in parallel, and by doing so, are affecting the devices detection/reaction time, causing LESS effective protection.

It may also relate to how the upstream device can/cannot adapt to the feedback loop that it may require for effective protection.

I figure: They designed it, they built it. If they say "Don't do this, it's a BAD THING," I gotta believe 'em.

There are non-protected power strips, just use one of those (don't overload the UPS).


FWIW

Scott