dana@gmu90x.UUCP (J Dana Eckart) (06/29/88)
As my investment in computer equipment increases, I become more and more concerned about how to protect it. Namely, what can I do to reduce the risk of damage via power and phone lines, particularly from lightning. As I understand it, there are basically two ways to protect the power source: line conditioning and/or uninterruptible power supplies. It would seem that UPS is best, but of course it can cost a great deal (upwards of $1000) whereas line conditioning can be had for much less (about $200). Given the prices, I would like to get by with just line conditioning. Will this provide satisfactory protection, even when hard disks are involved? What companies/models are best? How much protection against lightning strikes can I expect to get from either line conditioning or UPS? In the case of UPS, if commercial power goes out, is it possible to automatically signal the computer to do initiate system shutdown while battery power is still available? Likewise, there are protection boxes for telephone lines. Are these devices capable of making my modem safer from lightning strikes? As you can see, I just need some basic information. I would appreciate anything you can share. Thanks in advance. J Dana Eckart UUCP: ...!(gatech | pyrdc)!gmu90x!dana INTERNET: dana@gmu90x.gmu.edu SNAIL: P.O. Box 236/Fairfax, VA 22030-0236
bernie@codas.att.com (Bernie Brown) (07/01/88)
In article <1188@gmu90x.UUCP>, dana@gmu90x.UUCP (J Dana Eckart) writes: > > ... what can I do to reduce the risk of damage via power and phone lines, > particularly from lightning? > > As I understand it, there are basically two ways to protect the power > source: line conditioning and/or uninterruptible power supplies. True, BUT the reliability of both depends on how close to you the lighting strikes. The closer the strike is, the less chance you have of stopping it. The UPS is better and more expensive (your price guess was close enough). We use them here at work, but we also have over $50K in equipment. Some of them do have the capability to send an electical signal when the power fails. Then you just have figure out how to wire up and teach the computer how to interpret the signal and respond to it (not an easy job). > Likewise, there are protection boxes for telephone lines. Are these > devices capable of making my modem safer from lightning strikes? Usually the telephone company's protector should be enough. If the strike gets through it, it will probably get through anything else. But, heck, it couldn't hurt. SIDELIGHT: Living in central Florida, the alleged lighting capital of the world with thunderstorms almost daily for the entire summer, gives one a great appreciation for the power of lighting. A paramedic got stunned two days ago while getting into the rescue truck inside the garage. OUCH! Hope this helps a little. Bernie bernie@codas.att.com -- Bernie Brown AT&T, Altamonte Springs, FL (305)767-2668 bernie@codas.att.com
berger@clio.UUCP (07/01/88)
Line conditioners help protect against spikes from motors turning on,
RF interference, etc. They don't protect effectively against lightning
strikes. Likewise, the telephone protectors have little value. They
need a proper ground to have a chance of working - and I have NEVER
seen one installed with a proper ground. The ones made to plug into
an electrical outlet are useless.
Unplugging your modem from the phone line while not in use will help.
Mike Berger
Department of Statistics
Science, Technology, and Society
University of Illinois
berger@clio.las.uiuc.edu
{ihnp4 | convex | pur-ee}!uiucuxc!clio!bergerdca@kesmai.COM (David C. Albrecht) (07/02/88)
In article <1188@gmu90x.UUCP>, dana@gmu90x.UUCP (J Dana Eckart) writes: > > As my investment in computer equipment increases, I become more and > more concerned about how to protect it. Namely, what can I do to > reduce the risk of damage via power and phone lines, particularly > from lightning. > There are a number of ways to protect power lines etc.. from surges/sags etc. The most popular elements for surge protection are MOVs which protect from surges by shorting the spike to ground. The point at which the MOV starts shunting to ground depends on the device so there are MOVs for low-voltage lines like RS232 connects and phone lines and high-voltage lines like AC power. Most of the common plug surge protectors for the power line, RS232 line and/or telephone line are based on these devices. The more wires in the line you are trying to protect the more points at which the surge can appear. An RS232 surge protector will often only protect a few of the 25 lines. Haven't pried apart a telephone style surge protector to see what they protect. Power-line surge protectors are dealing with only three lines so they are often more sophisticated and offer protection of both of the power lines to ground and also a MOV between the two lines. More sophisticated line power protection devices will add filter networks to eliminate Radio Frequency noise from the line and additional elements to provide more protection than just MOVs alone. A surge protector will usually be rated for how much energy it can absorb in Joules (higher the better) and suppression of RF noise it will suppress in DBs. Line conditioners add voltage regulation to circuitry for surge suppression and noise suppression. The utility company isn't too careful about keeping voltage at 110 and it will often vary substantially from that point. If they have a hard time keeping up with demand they might just lean it out by reducing voltage to the community. The voltage regulator will adjust voltages within a certain range to maintain a solid 110 volts. I have a Tripp-Lite 1800 watt line conditioner and it regulates from 96v-138v to a solid 110v, it also incorporates all the surge and noise suppression of their ISOBAR line of surge protectors. At 1800 watts I can put a substantial amount of equipment on it and it only cost $200. The 1200watt model runs about $150 and should still handle every bit of computer equipment you own. UPSen come in two flavors on-line and off-line. Off-line are supplys that normally are monitoring the line but not adjusting its content in any way. The off-line supply therefore will typically not have any better surge and noise suppression than a good surge suppressor since it is probably using a similar network. Typically, it doesn't provide the voltage requlation of a line conditioner. It doesn't protect against overvoltage (until the level of the surge suppression network which is high) and low voltage isn't recognised until the voltage drops low enough to kick in the backup circuitry (which is typically fairly low). This kind of supply also has a finite switching time required to recognise power failure and switch to battery generated power. Typical switching times are on the order of 2ms. The reason people buy off-line UPSen is that they are often considerably cheaper than the on-line variety and they consume very little power when they aren't needed. They on-line variety is always generating the power to your equipment it is just where it is getting the input from that changes either line or battery. Therefore, there isn't any switching time and the power output is always conditioned. I also have a KNAPCO 550 watt UPS which is an off-line type containing some surge supression, no noise suppression that I know of. It switches in 2ms. The price was very good (about $370 qty 1, and I got the qty 10 price which was even better). The cheapest on-line varieties I have seen run around $700 similar or less watt output. If you want genuine protection against power outages then go with an UPS system. If protection against spikes is what you desire buy a good surge suppressor (< $100). A line conditioner will add voltage regulation to spike and noise suppression for not too much more money (< $200). For surge/noise/voltage/power-out protection go for the on-line UPS or off-line with a line conditioner in front of it. This will give you some measure of protection against nasty power lines and surges from lightning that isn't direct hits. The best protection is still a foot of air between the plug and the wall :-). Very close lightning strikes can induce voltages in lengths of wire and fry all sorts of unexpected components. Best you can hope for is some measure of security, it is unlikely you will ever get absolute protection. Sorry about the length, but you asked for it. David Albrecht
dca@kesmai.COM (David C. Albrecht) (07/02/88)
In article <1188@gmu90x.UUCP>, dana@gmu90x.UUCP (J Dana Eckart) writes: > > In the case of UPS, if commercial > power goes out, is it possible to automatically signal the computer > to do initiate system shutdown while battery power is still available? > All that text and I left something out. Some UPSen provide a relay which will close when the UPS is getting near the end of its power supply. You have to wire a connector that will interface to a port on your equipment and have some process monitoring that port and recognise when the relay switches. i.e. it can be done but it usually isn't pretty. At the Office in addition to the raft of Knapcos we have we have our uVAX on an American Power Conversion 1200 VX (which we also got from KNAPCO) that has such a relay. We haven't gone through the hassle of trying to figure out how to get it to do anything for us yet, however. David Albrecht
jbn@glacier.STANFORD.EDU (John B. Nagle) (07/04/88)
Whenever someone discusses lightning protection and computers, they
seem to conclude that full protection against a direct lightning strike on
a power or phone line is hopeless. This is simply not so. Antenna
towers are frequently struck by lightning; for some installations, it's
a normal event, occuring hundreds of times a year. The problem can be solved.
A serious lightning arrestor consists of several stages. The first
is an air gap to ground, with big contacts spaced a short distance apart.
Dime-sized silver contact faces are not uncommon. The connection to ground
must be very heavy copper connected to a small farm of ground rods, which
may also be tied to the ground of the electrical distribution system.
The second stage is an inductor, to block the lightning surge and
force it across the air gap to ground. This coil is typically just a
few turns of copper busbar. In some cases, it's just a few loops of
the normal power or coax cable. But tight turns of busbar inside a
grounded metal can are better.
The big energy having been dumped to ground, now we're ready for
the usual "surge suppressor" electronics, the MOV devices and such.
Heathkit used to sell a soup-can sized unit that contained stages
1 and 2 above, equipped with coax connectors on each end. But I don't
know a good source for such things today. Try ham radio suppliers.
This is exactly what is needed where an Ethernet cable enters a building.
The ARRL Handbook, section 37-4, contains some useful information
on lightning protection.
John Naglelyndon@ncc.Nexus.CA (Lyndon Nerenberg) (07/05/88)
In article <178@kesmai.COM> dca@kesmai.COM (David C. Albrecht) writes: >In article <1188@gmu90x.UUCP>, dana@gmu90x.UUCP (J Dana Eckart) writes: >> In the case of UPS, if commercial >> power goes out, is it possible to automatically signal the computer >> to do initiate system shutdown while battery power is still available? >All that text and I left something out. Some UPSen provide a relay which >will close when the UPS is getting near the end of its power supply. >You have to wire a connector that will interface to a port on your equipment >and have some process monitoring that port and recognise when the relay >switches. i.e. it can be done but it usually isn't pretty. Actually, it's quite trivial. Have the relay switch the appropriate voltage onto the Carrier Detect pin of an unused serial port on the system when the batteries are getting low. At boot time, start a process that does a blocking open on the port. When the relay closes, CD is asserted, causing the open call to unblock and return. From that point, have the program initiate a shutdown sequence. -- {alberta,pyramid,uunet}!ncc!lyndon lyndon@Nexus.CA
peter@ficc.UUCP (Peter da Silva) (07/05/88)
In article <1188@gmu90x.UUCP>, dana@gmu90x.UUCP (J Dana Eckart) writes: > ... what can I do to reduce the risk of damage via power and phone lines, > particularly from lightning? > As I understand it, there are basically two ways to protect the power > source: line conditioning and/or uninterruptible power supplies. Actually, about the only way to really be sure you're not nuked by a lightning strike is to use a motor-generator. Not only does it isolate you from the power lines but it makes an impressive humming noise. :->, in case you didn't guess. -- -- `-_-' Peter (have you hugged your wolf today) da Silva. -- U Ferranti International Controls Corporation. -- Phone: 713-274-5180. CI$: 70216,1076. ICBM: 29 37 N / 95 36 W. -- UUCP: {uunet,academ!uhnix1,bellcore!tness1}!sugar!ficc!peter.
bobbyd@upvax.UUCP (Oswald Brews) (07/07/88)
In article <1010@ficc.UUCP> peter@ficc.UUCP (Peter da Silva) writes: >In article <1188@gmu90x.UUCP>, dana@gmu90x.UUCP (J Dana Eckart) writes: >> ... what can I do to reduce the risk of damage via power and phone lines, >> particularly from lightning? > >> As I understand it, there are basically two ways to protect the power >> source: line conditioning and/or uninterruptible power supplies. > >Actually, about the only way to really be sure you're not nuked by a >lightning strike is to use a motor-generator. Not only does it isolate >you from the power lines but it makes an impressive humming noise. > >:->, in case you didn't guess. I can see it now - firing up the 18cyl Cat diesel before switching on the Vic-20... 8-) But then again, I own a PERQ, which houses a 900-pound 14" Shugart hard disk, and on powerup the neighbors think a DC10 is taking off next door...the lights dim, the floor starts to rumble and vibrate, the air pressure in the room drops as the fans kick in, loose buttons are pulled from clothing... 8-) 8-) 8-) Chris Lamb, PERQ Maniac. Yes! Shut this man up! Send him PERQs!! bobbyd@upvax -or- bobbyd%upvax@tektronix.tek.com
jbn@glacier.STANFORD.EDU (John B. Nagle) (07/08/88)
Synchronous motor-generators are very effective in blocking noise,
sags, spikes, lightning, and such. They are widely used in mainframe
computer installations; some IBM and Cray machines run all the power
supplies on 400Hz, and use a M-G set to convert 60Hz to 400Hz.
My own experience with an M-G set was very satisfactory; we had
one in a UNIVAC installation in a heavy industrial R&D facility, and
experienced no power problems, even during electrical storms. The
M-G set was a vertical-axis unit about 2.5' in diameter and 3' high.
It was a bit noisy, and was located in a nearby electrical switchgear
room, rather than in the computer room itself. This unit provided
excellent isolation from such nearby sources of interference as arc welders,
magnetic-pulse presses, and locomotive-transmission test stands.
Small M-G sets (a few KW) do exist; contact your local GE or
Westinghouse distributor. It's quite reasonable to have one in any
installation large enough to have a real computer room. They are much
cheaper than UPSs, and are very reliable; the technology of rotating
electrical machinery is well-developed.
John Naglemorrison@ficc.UUCP (brad morrison XNX SE#) (07/09/88)
In article <10310@ncc.Nexus.CA>, lyndon@ncc.Nexus.CA (Lyndon Nerenberg) writes: ~ In article <178@kesmai.COM> dca@kesmai.COM (David C. Albrecht) writes: ~ >In article <1188@gmu90x.UUCP>, dana@gmu90x.UUCP (J Dana Eckart) writes: ~ ~ >> In the case of UPS, if commercial ~ >> power goes out, is it possible to automatically signal the computer ~ >> to do initiate system shutdown while battery power is still available? ~ ~ >All that text and I left something out. Some UPSen provide a relay which ~ >will close when the UPS is getting near the end of its power supply. ~ >You have to wire a connector that will interface to a port on your equipment ~ >and have some process monitoring that port and recognise when the relay ~ >switches. i.e. it can be done but it usually isn't pretty. ~ ~ Actually, it's quite trivial. ~ ~ Have the relay switch the appropriate voltage onto the Carrier Detect ~ pin of an unused serial port on the system when the batteries are ~ getting low. Or, better yet, get a Micro-Ferrups UPS (Model M1000VA or M1500VA) from Best Power Technology and connect to their RS232 port for status messages-- including the estimated amount of time left until the batteries drain. 1-800-356-5794 . . . no affiliation, just satisfaction. -- Brad Morrison (713) 274-5449 {uunet,academ!uhnix1,bellcore!tness1}!sugar!ficc!morrison