RE: Power options

ahh I think I see what you mean...

Line(mains) ->-> UPS ->-> SurgeProt ->-> Computer

yes, seriously bad idea...

==

...but

Line(mains) ->-> SurgeProt ->-> UPS ->-> Computer

at the moment I can't see a lot wrong with this arrangement do you have different sorts of surge protectors in USA from what I'm used to here in UK?

best wishes, HJ

 

Hugh Jarss, Since you're not getting much attention I'll give you my opinion on the subject.

A surge protector is always cheap insurance, wherever you choose to place it. It is designed to protect downstream electronic equipment from harmful voltage spikes and it usually ruins the surge protector when it does that. Most good ones have indicator lights that will let you know when it has been hit by a harmful surge. Generally there is an internal fuse that will blow causing loss of service through the device. The better ones have provision for protecting the power line as well as telephone and television feeds.

I would advise that they be connected as the first device from the electrical outlet and as soon in the telephone or television line as possible.

As you mentioned, placing it downstream of the UPS would be inappropriate since it wouldn't protect the UPS, only the computer. It wouldn't do any harm, just wouldn't be doing all that it could. The sooner you intercept the surge, the better.

Reference

 

surferdude -

you've cheered my heart! I wish someone would have a crack at the unknown device thing, it's driving me nuts...

thanks for the reference etc -

what I was really after was, from the way Newt describes it, there's some blow-up mechanism involved using the two devices in conjunction - and for the life of me I can't see it - unless, if between between the UPS and the computer you could have
- bad news for the UPS if for some reason the surge protector fails to short (as they tend to do on severe overload) iff surge protector unfused

but like you say the good ones are fused - it wouldn't get hit by the surge anyway if downstream of the UPS - if surge big enough to make the surge protector protect is coming out of UPS output in the computer's direction then computer would get clobbered anyway

only other possibility I can see is down to some UPS outputs being seriously different to sinewave - if it's too "peaky" the tops of the peaks might take the surge protector to low-impedance (clipping the peaks) which could overload the UPS output - bit of a long shot though

neither of these mechanisms really "rings true" - so I still worry I'm stupidly missing something here? maybe something to do with the other circuits (TV, phone line)

very best wishes, HJ

 

Most of the major brand UPS have surge protection built in, so there isn't a need for two units. I depend on my UPS to level out the power fluctuations, and because of the constant dips and spikes, a surge protector would probably interrupt that feature of the UPS.

Johanna

 

I respectfully disagree Johanna. I would much rather have a transient spike fry my $15 surge protector (in-line ahead of all other devices) rather than my $100 UPS built in surge protector. I think repairing the UPS would cost more than replacing the cheaper surge protector.

Quoting from the link I supplied (same link that PeteC supplied incidentally):

If you live in a rural area with overhead utilities and lightning is common, along with power outages, I'd recommend a good UPS and a surge protector ahead of it that includes telephone and tv coax protection.

If you live in an area with all underground utilities and lightning is not common (or power outages), you may choose to gamble as I do and not have the UPS. I would still recommend the surge protector since many harmful spikes originate from your in-house appliances, especially switching of high inductance items like electric motors. Light dimmers are another common source of spikes but are not normally destructive.

 

large difference between UK and US re: Surge Protectors - different mechanisms involved because N linked back to E differently. Interesting...

best wishes, HJ

 

Hugh, You lost me there. What are N and E designating?

Perhaps you're referring to the line frequency and voltage. The basic concept and preferred protective device would remain the same. The clamping level would be different for a higher voltage system such as 220 volts. Generally the MOV (Metal Oxide Varistor) is used to shunt any detected surge to ground (or the opposing phase if no grounded conductor exists). The clamping level for 120 volt systems is normally 400 volts or lower with 330 being preferred. These are peak voltages and not r.m.s values. RMS values times 1.414 equals the Peak value.

It would be reasonable to assume the clamping level would double for the 220 volt systems found in Europe. That said, you'd have to get a device designed for the voltage of your system.

Edit: I see Belkin offers a universal surge protector that will auto-adjust its voltage to match the system.

Belkin Universal Surge Protector

 

Hi surferdude

all very true

it was thinking of the kinds of surges, rather than their size, which I was finding interesting

three wires in a mains lead (power cord)
L live (hot)
N neutral (cold)
E earth (ground)

with the US system the N and E are linked far more "tightly ", closer to the house than in the UK;

in UK although the earth (ground) is connected to eg water main, the N generally goes back to (or towards) the substation and is shared with other houses at a common distribution point

which means we can get "hit" down the N wire in a way which doesn't happen on the US system... what I meant by "different mechanism"

(common mode : L&N go "up and down" together, give or take)

...one consequence for UK is that surge protectors which hang the MOVs between L and E (like the pictorial one of the HowStuffWorks first page), but don't do the anything for the N, actually make stuff vulnerable which wouldn't be have been if "surge suppressor" not fitted

without a drawing!
UK: 240V RMS peaks at ~325V, the MOV's we use over here cut in around 380V;

L: N: E:
240 0 0 before spike : equipment sees 240V
5240 5000 0 with +5kV common mode spike : equipment sees 240V
380 5000 0 with spike and L held down with MOV to 380V - whoops: equipment sees 4760V

(oversimplification to indicate mechanism!)

best wishes, HJ

 

Hugh, The surge protector diagram you reference is oversimplified for purpose of explanation I suppose. A device wired that way would have severe limitations as you have pointed out and would never pass muster with the UL Lab. for a listing. To protect against all modes of surges, it requires three MOV's (or more if using parallel ratings) connected in all possible modes, line to neutral, line to ground, and ground to neutral. Anything that has the UL sticker will have such a configuration.

Therefore, your observation is correct about the "How things work" pictorial diagram. Just be sure you get one equal to the UL 1449 rating and you'll be properly protected, even against common mode and neutral spikes and surges.