Thunderstorms and Computers

The batteries are supposed to be changed every 3 years. They are sealed lead acid batteries and aren't that expensive to replace. The actual UPS itself should last for years and years.

The "Smart-UPS" range is at the top end (they're very good, it's what I use), you could get a 500VA "Back-UPS" for half that price from Overclockers. You lose some surge protection (300J vs 480J) but that isn't really so much of an issue in the UK. But for basic UPS protection they are just fine and very reasonable priced - it's only got to save you one wrecked hard drive and it's paid for itself.

thanks, that definately something to bear in mind.

ok, so whilst we are going into details, where and approx how much would a replacement battery cost? What i mean is, if i were to get an APC UPS, would i have to replace it with an APC battery, or are they generic?

Out of curiosity, how many times has your UPS saved you (that you know of)?

It's saved me twice that I know of. But I don't have a key meter, and I don't leave the PC's switched on when I'm not around. I suspect I would have been saved several more times if I did.

Officially, you are supposed to use the proper batteries, but I wouldn't mind betting that it's easy to get generic replacements from Maplins, though I've never specifically looked.

A couple words about surge suppressors. As said,stay away from the $9.95 "specials". Case in point: Client had a problem with monitor either not coming on or phasing out to blank screen. A lot of footwork done on this one. Solution found with a simple voltmeter. 6 connectors on the surge strip. First one(next to wall cord) tested 114v. #2=96v, #3=75v, #4&5=52v, #6(monitor plugged to this one) =15volt! Bottom line? The cheapo's are garbage! :rolleyes: If you need to go with a suppressor rather than a UPS for whatever reason, be sure to get a 'name' brand in the $30 to $40.00 range. And be sure it has a joule rating of at the very least,270 to 1,000. Or spend a bit more for one with a rating of 1100 and up.

Thanks peeps :)

If you have a refrigerator, freeze, air conditioner, on the same line as the PC, I can guarrantee that everythimg they start up, you have a brown out situation. And when they shut down, they spike the circuit.

I do have a mobo that those spikes destroyed, as a momento, sitting right above my monitor. Oh, the cpu and ram were gotten also.

And should you get that spike feedback throught the mains {main panel box} , you PC can still be damged.

Or if you have a place on the same feeder lines, that has large electrical motors, you can have the same situation coming in from the transformer on the pole that feeds your house.

Yes indeed, Train raises some very good points. Getting zapped by lightning, even in prone parts of the world is still a rare event, but getting zapped by mains spikes is not. Most people don't realise how dirty mains electricity is, and that is another very good reason for a good quality surge protector or UPS.


Let us discuss protection ratings. I have a number of electrical engineering qualifications, so I probably know more than most folks about what a Joule is and how it relates to other electrical units. But saying that my UPS's have a "Surge energy rating" of 480 Joules doesn't tell me anything very meaningful, and it presumably means even less to the average person who hasn't studied electromagentism. So how do we decide on what is an adequate protection rating? How does xxxx Joules relate to what we might experience in the real world with a lighning strike or mains spike?

What is an electrical surge?

A surge is a transient (i.e., momentary, impermanent) increase of current, voltage or power on an electrical system. The increase can be quite large – many times the norm – or quite small – 10 percent over the norm.

The larger, more destructive surges, generally caused by lightning, can reach thousands of volts. Lightning doesn’t have to strike the earth to cause damage. More common cloud to cloud strikes, even a mile away, can produce enormous magnetic fields that induce surges onto power, telephone and cable lines. Unchecked, such surges can quickly destroy wiring, appliances, telephones, and other electronic devices.

Smaller surges may be caused by disturbances on the utility’s transmission lines. Commonly, surges originate within the home from the operation of appliances such as refrigerators/freezers, washing machines, air conditioners, dishwashers, lighting dimmers, and power tools.

Surge protectors: what they are, how they function:

Surge protectors limit surge voltages by discharging surge currents to ground. Proper grounding is the strongest prerequisite for proper surge protection. The key components in almost all surge protectors are metal oxide varisters (MOVs). Under normal conditions, MOVs offer high resistance to currents, preventing normal currents from discharging to ground. Under surge conditions – typically 115 percent or more of normal current – the MOV’s resistance drops within nanoseconds (a nanosecond is one billionth of a second), creating a path with far less resistance than the facility’s wiring for the current to flow to ground.

Two stages of protection necessary to effectively guard against electrical surges:

Surge strips are commonly believed to be sufficient protection for electronic equipment such as televisions and personal computers. Surge strips, however, are not capable of suppressing a powerful surge, such as one caused by lightning, and most do not include any protection for telephone or coaxial cable lines. Although no product can protect a home against a direct lightning strike, the Institute of Electronics and Electrical Engineers recommends whole house surge suppression as the most effective way to protect against damage in the home.

Whole house surge suppression devices protect the home where the electric, telephone, and cable lines enter the home. These devices serve as a first line of defense against surges and are installed directly at the circuit breaker panel or fuse box to protect all incoming lines.

Now if you are in the market for suge protection, here are some thing to take into concideration.

1. UL 1449 LISTED
Look for an (Underwriters Laboratory) UL 1449 compliance rating for safety. The 1449 rating should be listed on products that conform to rating standards. A UL listing for "power tap" is not sufficient.

2. PEAK SURGE CURRENT
The peak surge current also may be referred to as maximum transient current or maximum current. The bigger the number, the better the protection. With surge protection at the meter or circuit panel, 36,000 amperes or higher are needed. Without surge protection at the meter or circuit panel, 54,000 amperes or higher are needed.

3. UL 1449 SUPPRESSED VOLTAGE RATING
The UL 1449 suppressed voltage rating is sometimes referred to as clamping voltage. The lower the number, the better the protection. As a general rule, 330 volts provide an adequate level of protection.

4. Energy Rating (Joules)
The joules testing method is not standardized; therefore, purchasing decisions should not be based on this rating alone. However, the higher the joule rating the better the protection. A rating of 600 joules or higher is considered adequate.

And some other things to concider.

Does the surge protector device protect other items from surge damage, such as TV cable or the telephone lines.

Does the surge protector come with a warranty for connected equipment? Many devices carry insurance on connected equipment of $25,000 or more.

Does the device allow for all equipment to be plugged into it, such as AC adapters or wall transformers, printers, monitors, and sound systems?

Does the surge protector protect against electrical noise such, as ElectroMagnetic Interference (EMI) or Radio Frequency Interference (RFI)?

Does the surge protector have an indicator light to show fault conditions, as well as a power-on indicator?

Do not go just by the joules ratings there have been manufactors who have used what I concider the wrong mov's just to raise that rating.[/b]

Dug out this table of terms.



Ampere
Quantitative unit of measurement of electrical current. Abbreviated as Amp or A.

Clamping Level
This generally is used to describe the voltage level, which causes the surge diversion device to start to divert surge energy. A related, but more important parameter is the Suppressed Voltage.

Response Time
The time it takes a surge protection device to switch from its "off" condition to an "on", diverting mode. This occurs when an incoming surge voltage exceeds the clamping threshold level of the MOV or other suppression component.

Common Mode Voltage
A voltage, that appears on the phase and neutral wires of the power system when compared with the system ground wire.

Current
Current, expressed in units of amperes, or simply amps, is the flow of electrons through a conductor. AC, or alternating current, is a current in which the flow of electrons reverses periodically.

Joule
A joule is a measure of the energy contained in an impulse or conversely it is a measure of the absorption capability of a surge protection device. (1 joule = 1 watt x 1 second)

Let-Through Voltage
The residual transient voltage that would appear across equipment after an upstream surge protection device has operated. It is important to remember that the "let-through" voltage is the sum of the voltage drop across the surge protector itself plus the voltage drops that appear across the wiring that connects the protector to the power lines. The protector clamping voltage is only one part of the let-through voltage and frequently is of secondary importance to the wiring drop.

Resistance
A property of electrical conductors or electrical insulators, which characterizes their ability to conduct or resist the flow of electricity.

Service Life
The number of surges of given magnitude that can be suppressed by the suppressor, a measure of reliability.

To continue for an average computer setup with printer and scanner about an 1100 joule rated surge protecor will work.

And you can use the table above to make sure you cover all the specs.

It is not uncommon because of the arc over at the electrical entrances that the individual outlets can have 6,000V and 3000 amps present when the spike hits. And we have not said anything about inductance and distance.

And what about the effect of large machinery loads being turned on and off in an electrical grid. these spikes will hit you too.

If you were to connect a circle graph to your electical supply and ran it for twenty four hours you would be amazed at the number of highs and lows you received.

WOuld I be right, in theory, that if you dasiy-chained 2+ surge strips or even UPS's you would get better protecttion? Ignoring the impracticality of it, say one bought 2 UPS's/Surge Strips I am thinking along the lines of if daisy-chained, the first one would take the 'big' buffer, then the second one would sort out any 'excess' that made it through...

Would I be right in presuming this?

Quote:

---

Originally Posted by SuperSparks

So how do we decide on what is an adequate protection rating? How does xxxx Joules relate to what we might experience in the real world with a lighning strike or mains spike?

---

Yes indeed.

We can see from this thread that generalized statements as to what's adequate for certain things can vary. In BJ's post Semantec says

Quote:

---

A good suppressor can absorb around 200 to 400 joules before it fails and passes the surge to the electrical ground.

---

Yet Train's source says

Quote:

---

A rating of 600 joules or higher is considered adequate.

---

That would seem to be a not so insignificant difference.

Quote:

---

WOuld I be right, in theory, that if you dasiy-chained 2+ surge strips or even UPS's you would get better protecttion?

---

Acording to Tripp Lite...

Quote:

---

Can you daisychain surge suppressors?
Yes, but it is not recommended. By connecting all the surge suppressors into one, an overload may occur and trip the circuit breaker. Also surge suppressors protect against AC surges and spikes by way of MOVs (Metal Oxide Varistors) and these devices should not be put in series.

---

Now as Train mentioned...

Quote:

---

If you have a refrigerator, freeze, air conditioner, on the same line as the PC, I can guarrantee that everythimg they start up, you have a brown out situation.

---

But basic surge suppressors, and even UPSes, do not offer any protection from this if they employ fixed (as opposed to dynamic) clamping levels via the MOVs train mentioned.