Uninterruptible Power Source FAQ

Archive-name: UPS-faq
Version: 1.9


Uninterruptable Power Source (UPS) FAQ.
VERSION 1.9, July 11, 1995


Sections:
	01: What is this document all about?
		01: What is this document?
		02: How is this document made available?
		03: Who maintains this?
		04: Where did this information come from?
		05: How can I contribute?
		06: How may this document be distributed?
		07: Got anything else you'd like to add?
		08: Glossary.
	02: What is a UPS and how does is work?
		01: What is a UPS?
		02: How do you pronounce "UPS"?
		03: Vendor X says that (description) is a UPS, is it?
		04: Describe the types of UPS's?
		05: How can a UPS help me?
		06: What sort of stuff does a UPS do?
		07: How long can equipment on a UPS keep running?
		08: What is a "good" UPS?
		09: Support contracts on UPS's.
		10: Self maintenance tips.
		11: Is a UPS a glorified power strip?
		12: How important is the UPS output waveform?
	03: UPS monitoring/shutdown software.
		01: Can a UPS shut the computer down when power is low?
		02: Can I write my own shutdown routines?
		03: What freely distributable solutions are there?
		04: No UPS software works on my machines, what to do?
		05: What other software is out there.
	04: How big a UPS do I need?
		01: How are UPS sizes determined?
		02: What VA rating do I need?
		03: How do I determine this?
		04: What else should I consider?
		05: Can I use an UPS with a laser printer?
		06: What UPS sizes do you use on what equipment?
	05: Specific manufacturer's info.
		01: What vendors are there?
		02: UPS Hardware.
		03: UPS Software only.
		04: Other companies.
	06: Bibliography
	07: Acknowledgments

-----------------------------

01:
TOPIC:	What is this document all about?

01.01
Q:	What is this document?
A:	This is a FAQ document on Uninterruptable Power Sources.  It is 
	intended to provide a starting point for those people that want 
	to find out what they are, what they do, and what's available.

	Note that most of this document is very US-centric.  The power
	numbers, companies and services all emphasize US consumer 
	needs.  Sorry, but that's what I have to work with.  All the
	principles discussed here should be applicable just about 
	everywhere.

01.02
Q:	How is this document made available?
A:	Currently, its "home" is comp.misc.  It is also crossposted to 
	comp.unix.admin, comp.sys.sun.hardware, comp.sys.hp.hardware, 
	comp.sys.sgi.hardware, comp.sys.next.hardware, 
	comp.sys.ibm.hardware, comp.sys.dec, comp.answers and 
	news.answers.  This posting is automated and will occur on or 
	near the 10th of each month.  If there are other groups to 
	which this document should be posted, please let me know, but
	if I post it to every group where UPS questions get asked, that
	would be a lot of groups.  I'm open to suggestions.

	This document is also available via anonymous FTP.  The master
	sits on navigator.jpl.nasa.gov (128.149.23.82) in pub/doc/faq
	as the file UPS.faq.  It is also available via anonymous FTP
	from rtfm.mit.edu in: 
	pub/usenet-by-group/comp.misc/Uninterruptable_Power_Source_FAQ  

01.03	
Q:	Who maintains this?
A:	Right now, this document is maintained by Nick Christenson.  My
	preferred email address is npc@minotaur.jpl.nasa.gov, and I 
	would like it very much if questions regarding this document
	could have the word "UPS or UPS FAQ" or some such in the Subject
	line.  Note:  I am maintaining this on my own time, so please
	don't be upset if it takes a while for me to respond to your
	queries.  Also none of the information in here represents the
	views or has the blessing of any organization whatsoever.  The
	maintainer of the FAQ is to be held solely responsible for its
	contents.

01.04
Q:	Where did this information come from?
A:	Thankfully, many people have rallied to my cry to fill in
	the many gaps in my original draft.  This is now a group work,
	although I claim full responsibility for misstatements and 
	inaccuracies.  
	
01.05
Q:	How can I contribute?
A:	You should mail new information, corrections, suggestions, etc.
	to the current maintainer of this FAQ.  If you provide a suggestion,
	make sure you reference where the information is located in the
	document.  I guarantee that suggestions of the form "Change the
	word 'always' to 'almost always' in the part about surge suppression."
	will be ignored.

01.06
Q:	Are there any restrictions on distribution of this document?
A:	This document is copyright by the author.  You are encouraged 
	to distribute this document for any non-commercial purpose 
	as long as the contents remain unchanged and a pointer to 
	an up-to-date version is included.

01.07
Q:	Got anything else you'd like to add?
A:	Yes, now that you mention it.  The people who contribute to this
	document can speak only about equipment they have experience with.
	This may reflect a bias toward or against certain brands, features,
	functions, etc..  Please keep in mind that the suggestions, brand
	names and functions here are by no means exhaustive, or even 
	necessarily applicable to your situation.  Also, if you have 
	information that is not in this document, please submit it to 
	the maintainer listed above.  If you submit information, please
	say whether you'd like it to be attributed to you or not.  I am 
	more than glad to give credit to the fine people who helped with
	this document, but I want to respect the anonymity of those 
	people who would prefer it.

	One more caveat:  While the principles of UPS design and 
	maintenance are likely to be fairly universal, the power 
	figures in this FAQ are *very* US-centric.  Sorry, but 
	they're the only numbers I have.

01.08
Q:	Glossary
A:	This was contributed almost entirely by some kind soul.  I just
	cleaned it up a bit.

	Blackout: Complete loss of power. Some literature considers a voltage
	drop below about 80V to be a blackout as well since most
	equipment will not operate below these levels.

	Sag or Brownout: Decrease in voltage levels which can last for
	periods ranging from fractions of a second to hours. Can be
	caused by heavy equipment coming on line such as shop tools,
	elevators, compressors etc. Also occurs when utility companies
	deliberately do this to cope with peak load times.

	Spike: An instantaneous and tremendous increase in voltage often
	caused by a direct lightning strike on a power line or when
	power returns after a blackout.

	Surge: An substantial increase in voltage lasting a small fraction
	of a second, often caused when high powered appliances such as
	air conditioners are switched off.

	EMI/RFI Noise: ElectroMagnetic Interference and Radio Frequency
	Interference. Caused by, inter alia, lightning, generators,
	radio transmitters, industrial equipment.

	MOV: Metal Oxide Varistors used to control spikes.  These are
	common in Power Strips.  If you see more than two, you likely
	have a fairly decent Power Strip.  They look like largish disk
	capacitors.

	Inverter: Circuitry that converts DC battery power to AC power
	required by most computer equipment.

	Surge Protector: Circuitry consisting of MOVs, capacitors, rod-core
	inductors etc. for suppressing surges and spikes usually embedded
	in a power strip.

	Line Conditioner: A transformer that attempts to smooth out
	fluctuations in input voltage to provide near uniform output
	voltage or voltage waveform.


02: 
TOPIC:  What is a UPS and how does is work?

02.01
Q:	What is a UPS?
A:	An Uninterruptable Power Source is a device that sits between
	a power supply (e.g. a wall outlet) and a device (e.g. a computer)
	to prevent undesired features of the power source (outages, sags,
	surges, bad harmonics, etc.) from the supply from adversely 
	affecting the performance of the device.  

02.02
Q:	How do you pronounce "UPS"?
A:	I pronounce it "ups", but most of the literature seems to favor
	"you pee ess", since they use "a UPS" instead of "an UPS".  This
	document will try to follow the literature.

02.03
Q:	Vendor X says that (fill in description) is a UPS, but it's 
	different that what you describe above.  Who's right?
A:	There really is no standard definition of what a UPS is.  
	Anything ranging from a 9 volt battery backup in a clock radio
	to a building/compound wide backup generator has been called
	a UPS by someone.  The majority of this document refers to
	objects larger than a beer can and smaller than a desk that
	help devices remain temporarily operational when changes to the 
	power they receive would otherwise interrupt their function.

	Maintaining power to a minicomputer (like a VAX 11) is beyond
	the scope of this document.  This FAQ deals with UPS equipment 
	that can be installed by a computer owner/administrator.  If you 
	have requirements that large, you need to talk to a qualified 
	electrician.

02.04
Q:	Can you give me some more information on this?
A:	(Kindly provided by Don Deal, Don.Deal@oit.gatech.edu, my additions
	are in [square brackets] )

	The UPS industry is made up of many manufacturers, and there is 
	a lack of standard terms within the industry.  I think this 
	sometimes borders on deliberate misdirection. (It's a jungle out 
	there!)

	There are basically three different types of devices, all of 
	which are occasionally passed off as UPSs.

	1. Standby power supply (SPS). In this type of supply, power is 
	usually derived directly from the power line, until power fails. 
	After power failure, a battery powered inverter turns on to 
	continue supplying power.  Batteries are charged, as necessary, 
	when line power is available.  This type of supply is sometimes 
	called an "offline" UPS.

	The quality and effectiveness of this class of devices varies 
	considerably; however, they are generally quite a bit cheaper than
	"true" UPSs.  The time required for the inverter to come online,
	typically called the switchover time, varies by unit.  While some
	computers may be able to tolerate long switchover times, your
	mileage may vary.  [ Some articles in the trade press have claimed
	that their testing shows that modern PCs can withstand transfer
	times of 100ms or more.  Most UPS units claim a transfer time to 
	battery of about 4ms.  Note that even if a computer can stay up
	for 100ms, it doesn't mean that 100ms switchover is okay.  Damage
	can still be done to a computer or data on it even if it stays
	up. ]

	Other features to look for in this class of supplies is line 
	filtering and/or other line conditioners. Since appliances 
	connected to the supply are basically connected directly from 
	the power line, SPSs provide relatively poor protection from 
	line noise, frequency variations, line spikes, and brownouts. 

	[Some SPS's claim to have surge/spike suppression circuitry as 
	well as transformers to "boost" voltage without switching to 
	the battery if a modest voltage drop occurs. An example is the 
	"APC Smart UPS" which claims it will switch to this boosting mode 
	if voltage drops below 103V (from the normal expected 120V) and 
	switches to battery only at 90V and below.  This, it is claimed, 
	allows operation of the equipment indefinitely under brownout 
	conditions as long as voltage does not drop below 90V.  I have
	not tested this, and would be interested in independent data.  
	There are other vendors products that make similar claims.]

	2. Hybrid UPS systems. I only know one vendor who sells them - 
	Best Power, Inc. The theory behind these devices is fairly simple. 
	When normal operating line power is present, the supply conditions 
	power using a ferroresonant transformer. This transformer maintains 
	a constant output voltage even with a varying input voltage and 
	provides good protection against line noise.  The transformer also 
	maintains output on its secondary briefly when a total outage occurs.  
	Best claims that their inverter then goes online so quickly that 
	it is operating without any interruption in power.  Other UPS 
	vendors maintain that the transition is less than seamless, but 
	then again it's not in their best interest to promote Best's products.  
	Best has a sizable part of the UPS market.

	[ Note:  According to some sources, ferroresonant transformers in an
	UPS system can interact with ferroresonant transformers in your 
	equipment and produce unexpected results.  The Moral:  Again, test
	before you buy.  -npc ]

	3. What I call "true" UPS systems, those supplies that continuously 
	operate from an inverter. Obviously, there is no switchover time, 
	and these supplies generally provide the best isolation from power 
	line problems.  The disadvantages to these devices are increased 
	cost, increased power consumption, and increased heat generation.  
	Despite the fact that the inverter in a "true" UPS is always on, 
	the reliability of such units does not seem to be affected.  In 
	fact, we have seen more failures in cheaper SPS units.  [ Note,
	though, that given the same quality inverter, you'd expect the
	one that runs least to last longest. ]

02.05
Q:	How can it help me?
A:	A UPS has internal batteries to guarantee that continuous power
	is provided to the equipment even if the power supply stops
	providing power.  Of course the UPS can provide power for a while,
	typically a few minutes, but that is often enough to ride out
	power company glitches or short outages.  
	Advantages:
		1) Computer jobs don't stop because the power fails.
		2) Users not inconvenienced by computer shutting down.
		3) Equipment does not incur the stress of another (hard)
		   power cycle.
		4) Data isn't lost because a machine shut down without
		   doing a "sync" or equivalent to flush cached or 
		   real time data.

02.06
Q:	What sort of stuff does a UPS do?
A:	A UPS traditionally can perform the following functions:
		1) Absorb relatively small power surges.
		2) Smooth out noisy power sources.
		3) Continue to provide power to equipment during line sags.
		4) Provide power for some time after a blackout has occurred.
	In addition, some UPS or UPS/software combinations provide the
	following functions:
		1) Automatic shutdown of equipment during long power 
		   outages.
		2) Monitoring and logging of the status of the power supply.
		3) Display the Voltage/Current draw of the equipment.
		4) Restart equipment after a long power outage.
		5) Display the voltage currently on the line.
		6) Provide alarms on certain error conditions.
		7) Provide short circuit protection.

02.07
Q:	How long can equipment on a UPS keep running after the power
	goes?
A:	How big a UPS do you have and what kind of equipment does it 
	protect?  For most typical computer workstations, one might 
	have a UPS that was rated to keep the machine alive through 
	a 15 minute power loss.  If you need a machine to survive 
	hours without power should probably look at a more robust
	power backup solution.  Even if a UPS has a very small load,
	it must still operate it's DC (battery) to AC converter, 
	which costs power.  A rough extrapolation from APC's 
	documentation, leads me to guess that a 2000 VA UPS can
	operate it's own converter (with no extra load) for just
	over 8 hours.  A 1250 VA UPS could run its converter for 
	about 5.  These are *very* rough guesses based on information
	provided by one vendor for one vendor.

02.08
Q:	Given the same vendor claims, how can I tell a "good" quality
	UPS from a "poor" quality UPS?
A:	Testing, testing, testing.  I can't emphasize this enough.  There
	are many good and bad units out there that call themselves UPS's.
	There are many good units that are wrong for your situation.
	Caveat Emptor.

	Some properties you might look for are:
	1) Sinusoidal power output.  In general, the closer the AC output 
	   of the UPS is to a sine wave, the better it is for your equipment.  
	   Many UPS units, especially the cheaper ones, deviate a great
	   deal from a sinusoidal output.  Some of them generate square
	   waves.  Waveform effects are dealt with in section 2.12.
	2) Does the UPS have a manual bypass switch?  If the UPS is 
	   broken or is being serviced, can you pass power through it to 
	   your equipment?  The last thing you want is for a broken UPS to 
	   be the cause of extra downtime.
	3) The more information about a UPS's operation you can get from
	   watching the unit itself, the better.  How much power (or 
	   percentage load) the equipment is drawing, how much battery
	   life is left and indications of the input power quality are
	   all very useful.
	4) Some newer UPS's can communicate with their monitoring software 
	   via network connection and SNMP!  This is wonderful *if* your 
	   network is on a UPS!  Also, beware, I have heard of dealers
	   advertising "Network UPS" monitoring where the network is 
	   the normal serial connection (no SLIP or PPP).  
	5) Does the UPS vendor offer support/maintenance contracts.  If
	   they don't even offer them, I would suspect the quality of the
	   equipment.

	If you do have a UPS that does not output a sinusoidal waveform,
	some manufacturers *strongly* urge you to not put a surge protector
	between the UPS and the computer.  The surge protector might mistake
	the non-sine waveform as a power surge and try to send it to ground.
	This could be bad for your UPS.  I don't know if this has happened
	or not, but I wouldn't chance it.

02.09
Q:	Should I make sure I have a support/maintenance contract for my
	UPS systems?
A:	Some people strongly recommend this, but to be honest, I don't 
	know how important it is.  I haven't had any UPS's long enough
	to have enough of them fail to know what the failure modes are
	likely to be.  Some people, with more experience than I in these
	matters, insist that a UPS support/maintenance contract is as
	important as your computer support/maintenance contract.  I can't
	argue with them.  In any case, it's almost certainly worth 
	pricing at any rate.

02.10
Q:	What sort of maintenance can I perform myself?
A:	One good thing you might want to do is periodically test the 
	UPS's and their failure modes.  A good time to do this might be 
	right after after a periodic level 0 backup.  Nobody is logged 
	in and you've got full backups of the machines.  Throw the 
	circuit breaker with the UPS on it to simulate and outage and 
	see how the transition goes.  Note that some UPS vendors suggest
	that testing an UPS by pulling the plug from the wall is *not*
	a good idea (Tripp Lite is one of them).  These UPS units like
	to have a good idea of what ground looks like.  It is likely that
	unplugging just about any UPS for a short amount of time would
	not be too dangerous (don't take my word for it, though!), but
	in all cases, throwing a circuit breaker would be a better thing
	to do. 

	It might be useful to install a GFI (Ground Fault Interrupter)
	socket to facilitate this testing without having to pull the plug,
	especially if you don't have your UPS protected machines on
	an isolated circuit (which you probably should).  These are the 
	sockets found in most modern kitchens and bathrooms with a red 
	and a black button. You push the latter to cut power and the 
	former to restore power.

	Those UPS units that use lead-acid batteries (that's most of 
	them, I'm told) do not have a battery memory and should be run 
	dry as few times as possible.  It's probably not a bad investment 
	to do this once on one UPS out of a largish batch to learn how 
	much UPS time you can expect in a real power outage.  Note:  
	depending on the manufacturer, UPS batters can be expected to 
	last between about 1 and 5 years before they ought to be replaced.

	As a UPS gets older, its battery life will become shorter.  Of
	course there's no way to reliably test how long it is without
	running the battery down and you don't want to do that because
	they have lead acid batteries.  <Sigh.>  All of these are very
	good reasons to get a support contract for them that includes
	periodic battery replacement.  At the very least, you can figure
	that the batteries will still be good at the end of the UPS 
	warranty figure, so that's a good place to start guesswork.
	
02.11
Q:	Isn't a UPS just a glorified power strip/surge protector with
	some batteries and a little power conditioning thrown in?
A:	Basically.  It's also got a power inverter and some other circuitry.
	It may also have a timer, thermometer or other gadgets.

02.12
Q:	How important is the UPS output waveform?
A:	That's a good question, and one is worthy of some debate.  One
	school of thought holds that one should always run equipment on
	the best approximation of sinusoidal input that one can, and that
	deviations produce harmonics which may either be interpreted as
	signal if they get through a power supply, or may actually damage
	the equipment.  Another school holds that since almost all 
	computers use switching-type power supplies, which only draw 
	power at or near the peaks of the waveforms, the shape of the 
	input power waveform is not important.  Who's right?  I don't 
	know.  My *opinion* is that sinusoidal output is worth the 
	extra money, especially for on-line UPS systems that continually
	provide their waveform to the computer.  Also, if you don't *know*
	that your equipment has a switching-type power supply, you might
	want to think twice before buying a low quality UPS.
	[ Some of this information from a great article in the October
	  1994 issue of LAN Magazine, check it out. -npc ]


03:	
TOPIC:	UPS monitoring/shutdown software.

03.01
Q:	If the power is out for a long time, I would like to have my
	computer automatically shut itself down gracefully before the
	UPS batteries die.  Can I do this?
A:	Yes.  Most UPS manufacturers support software that will do this 
	for some UPS's on at least some platforms.  Ask your UPS vendor 
	for details.
Q:	Okay, how about restarting the system for me once power returns?
A:	Fewer software products do this, but many do.  Again, ask your
	vendor.  I do not know of any freely distributable products that
	will do this.  It doesn't mean that they can't be built, but 
	vendor software is cheap enough (usually) that it's probably not
	worth building.

03.02
Q:	How does it work?  I'm a starving (fill in the blank) and I really 
	don't want to pay for software unless I absolutely have to.
A:	Usually, there is a serial connection running from a UPS into
	your computer.  The UPS sends information along the serial line
	as it goes.  If you can decode which pins contain which information,
	how the information is formatted and figure out what it wants to
	hear from the computer side, you're all set.  Make sure you have
	the right serial cable and know how the pins map between DB9 and 
	DB25 as both your computer and your UPS may take either.

	Since UPS units with network based monitoring capabilities are
	appearing on the market, we can hopefully get something that will
	communicate with those units.

	Here is a skeleton script provided by Joe Moss, joe@morton.rain.com.
	Definitely check this out as a starting point, but don't expect
	it to do anything meaningful without some work.


	---------start upsd.sh-------------
        #! /bin/sh

        # Shut down system in case of extended power failure

        # This should be the serial port to which the UPS is connected
        # This port must be set to block on open until the DCD line
        # is asserted - many UNIX systems have this determined by
        # the minor device number, if not, see if there is some way
        # to enable this behavior on your system
        PORT=/dev/ttya

        # Ok, this should block until there is a power failure

        : > $PORT

        # If we reach this point, we've lost power
        wall << EOF
        The sky is falling!! The sky is falling!!
        EOF

        # call shutdown (or init or whatever)
        exec shutdown
	-----------end--------------------

03.03	
Q:	Hmmm... that sounds kinda complicated.  Has someone already done
	this?
A:	Any solution would almost certainly be vendor specific.  However,
	some brave souls have provided partial functionality for certain
	vendors' UPS's.  I don't know the original source, but I have a
	copy available for anonymous FTP at navigator.jpl.nasa.gov in
	the pub/src/UPS directory as upsd.tar.Z.  I haven't tried it and 
	I don't honestly know if it even works.  

	Note:  Different UPS's produce different sorts of signals.  Just
	installing this already built package may require a great deal of
	work.  The cabling can be complicated, etc..  I would be 
	interested in hearing where this software does/doesn't work.

	Another good example, that probably works straight away for
	SunOS 4.1.X machines using APC Back-UPS devices, is also 
	available on navigator for anonymous FTP in the pub/src/UPS
	directory is pf.c.  It was written by Ronald Florence 
	(ron@mlfarm.com).  It looks like a nice framework for expansion
	to other OS platforms and UPS implementations.  Give it a try. 

03.04	
Q:	I can't find monitoring software that will work on my configuration.
	What should I do?
A:	Well, it seems you have a few choices:
		1) Build your own.  See item 03.02.
		2) Use something freely distributable.  See item 03.03.
		3) Lean on your UPS vendor to port to your platform.
		4) Try a different vendor that supports your platform.
		   See item 05.01.

03.05
Q:	What other software is out there?
A:	Software packages for UPS machines are getting more sophisticated.
	Most provide some level of power and status monitoring, but 
	lately there are more GUI's, more interactive packages, SNMP
	support, and even call-out paging.  See the software section
	05.03 for more info.


04:
TOPIC:	How big a UPS do I need?

04.01
Q:	How are the "sizes" of UPS's determined?
A:	Typically, a UPS has a VA rating.  The VA rating is the maximum
	number of Volts * Amps it can deliver.  The VA rating is not the 
	same as the power drain (in Watts) of the equipment.  Computers
	are notoriously non-resistive.  A typical PF (power factor: 
	Watts/VA) for workstations may be as low as 0.6, which means that
	if you record a drain of 100 Watts, you need a UPS with a VA
	rating of 167.  Some literature suggests that 0.7 may be a 
	good conversion factor, but this will depend heavily on the 
	machine.  WARNING:  Don't take my word for it!  Note:  Some UPS's 
	can continue to deliver power if the VA rating is exceeded, they 
	merely can't provide above their VA rating if the power goes.  
	Some can't provide power above their VA rating at all.  Some may 
	do something really nasty if you try.  In any case, I *strongly* 
	recommend not doing this under *any* circumstances.

04.02
Q:	How can I tell what VA rating I need for my equipment?
A:	First, when possible, get VA rather than wattage ratings.  See
	Q04.01 above.
	There are a couple of ways:
		1) Direct measurement.  You can get equipment to measure
		   the current draw of your equipment directly.  You may
		   or may not have access to this.  If you are part of an
		   organization that has it's own facilities/electrical
		   type people, they're likely to be able to do this.  They
		   might help you out if you ask nice.
		2) Compare notes.  If you know someone with the same setup
		   you're using, ask them what they use and how close they
		   are to the maximum VA rating.
		3) Use a chart.  Most vendors can help you out for common
		   equipment.  If you have an unusual setup, or mix 
		   vendors a lot, you're probably out of luck here.
		4) Use the equipment rating.  Most pieces of computer
		   equipment have a power rating on some back panel.  This
		   number is usually high, as it is necessary for the 
		   manufacturer to play it safe or they'll get sued.

	Note:  Method 1 is by far the best, method 2 and 3 are secondary,
	method 4 is usually overkill, but pretty safe.  There are some
	examples in section 4.6, but the information is probably worth
	what you paid for it :-)

04.03
Q:	Hmmm... seems like a tough thing to determine.
A:	Yeah, it can be.  It's also very important.  If you get a UPS 
	that's too big, then you've overpaid, but your equipment can 
	survive a longer outage.  If you get a UPS that's too small, 
	then you could be in deep trouble.  Therefore, I recommend that 
	you be conservative in buying these things, unfortunately, this 
	costs money.

04.04
Q:	What else should I consider?
A:	It would be nice to know how long your site's typical power 
	outages are.  In some places, with nice weather and a flaky
	power grid, the power is almost never out for more than 5 minutes,
	but this could happen quite frequently.  In this case, you may 
	as well use a UPS with a VA rating close to your equipment 
	rating with no extra batteries.  If your area has longer outages, 
	in the half hour or hour range, as is often the case in 
	thunderstorm country, you can either buy UPS's with multiples 
	of the VA rating of the equipment, since oversizing a VA rating 
	for a UPS has the effect of lengthening the amount of time your 
	equipment can stay up in case of a power outage, or you can buy 
	additional battery units for a smaller UPS.  You can probably 
	get away with doing simple math to determine how much longer a 
	larger UPS will keep your equipment running, but I recommend 
	running a few tests before committing to a large purchase 
	order.  Also, your UPS vendor will almost certainly be glad 
	to help you size the equipment you need.  If all else fails 
	and you guess wrong, or move equipment to a location with 
	different power status, you may be really, really glad if you 
	bought a UPS that can have additional battery packs added.
	
04.05
Q:	How about I use one of these UPS thingies for a laser printer?
A:	Don't *ever* do this.  If you ever measured the current draw
	of a laser printer during startup (and during printing) you'd
	be stunned at what it pulls.  All UPS manufacturers I know of
	tell you not to do this.

	Okay, I have to back down from this.  I know APC, just as an 
	example, now does rate some of their UPS units for use with 
	certain laser printers.  Not that I think this is a good
	idea, mind you.  In general, they are difficult to size and 
	rarely do they require the same level of uptime as servers.

	In any case, don't do this without specific approval of
	your UPS vendor.

04.06
Q:	So, what sorts of UPS sizes do you use on your equipment?
A:	BIG DISCLAIMER.  I disclaim everything about these figures.  
	At best, they are very, very rough.  Heck, I may be lying.  
	Don't trust them.  Here they are anyway.

	Note also, this is what the equipment apparently PULLS, not
	the UPS sizes that are on them.  Generally, I've been using
	UPS's that are about 2X the VA ratings shown.  At the very
	least, I would using UPS sized 1.5X the VA ratings here.

	400 VA:
	Sparc 2 with 3 600 MB disks, 1 200 MB disk, 1 exabyte 8200 
	tape drive, 19" color monitor.

	600 VA:
	HP 750 with 4 1.3 GB disks, internal 4mm tape drive and internal
	CD-ROM drive, external disk cabinet and 19" color monitor.

	500 VA:
	SPARC 2GX clone.  1 1.2 GB disk, 4 2.0 GB disks, 2 tape drives,
	1 CD-ROM drive, "big" monitor.

	300 VA:
	Sparc 2 clone with 100W power supply, internal 424 disk, 16"
	color monitor, external 1 GB disk drive.

	These are U.K. numbers, based on 240 V wall current.  Most of
	these VA numbers are very close to "American" VA numbers, but
	if my caveats weren't strong enough earlier... .

	100 VA:
	SGI Indigo R4400, 48 MB RAM, 1 GB int. disk, no graphics, no 
	monitor.

	580 VA:
	SGI Indigo R4400 configured as above with 17" Sony monitor plus
	3 19" monochrome X terminals.
	
	Another word of warning, don't assume that power requirements
	scale with compute power and number of peripherals, ESPECIALLY
	if they are different architectures.  Older equipment, CPU's,
	disks, monitors, whatever almost universally requires more
	power than new equipment.  For example, it seems that an HP
	9000/425e with 1 internal 420 MB disk and 19" color monitor 
	pulls a lot more power than a much more modern and much faster
	HP 9000/715 with an internal 1.3 GB disk, CD-ROM drive and 
	more modern 19" color monitor.  Again, the moral is don't assume.
	

05:
TOPIC:	Specific manufacturer's information.

05.01	
Q:	What vendors are there and what do they produce?
A:	Here is a very incomplete list, based only on what I know.
	Please give me information to expand it.  I make no claims
	as to the accuracy of this information.  It is mostly based
	on personal recommendations and vendor propoganda.

	Note:  The October 1994 issue of LAN Magazine has a great
	vendor list.  I have used it to update many of the entries
	here.  However, there is a lot of information available
	there that I don't have space to include here.  This 
	article is an excellent starting point for comparative pricing
	on UPS equipment.

05.02	UPS Hardware (and software) manufacturers:

	Company:		Acme Electric Corp.
				43 Argow Place
				Nanuet, NY 10954
	US Phone:		1-716-968-2400
				1-800-833-1373

	UPS Products:
		250 to 1400 VA standby UPS products, 1000 and 2000 VA
		on-line UPS products.  Shutdown/startup and SNMP 
		software for LAN Manager, Netware 3.x, 4.x, UNIX and 
		VINES.

	Contributed by:  Robert D. Freeman, rdf@thermo.chem.okstate.edu
		with additional information by npc.
	------------------------


	Company:		Advanced Electronic Systems, Inc.
				2005 Lincoln Way East
				Chambersburg, PA 17201
	US Phone:		1-800-345-1280
	Email:			None known

	UPS Products:
	Stediwatt UPS:  Designed specifically for use with NeXTSTEP.

	Contributed by:  Robert D. Freeman, rdf@thermo.chem.okstate.edu
	------------------------


	Company:		Alpha Technologies
	US Phone:		1-206-647-2360
				1-800-322-5742

	UPS Products:		
		600 to 15000 VA line-interactive UPS systems, SW
		with shutdown and SNMP support.  250 to 750 VA 
		standby UPS systems.

	Contributed by:  npc from LAN Magazine, October 1994.
	------------------------


	Company:		APC, American Power Conversion
	US Address:		132 Fairgrounds Road
				P.O. Box 278
				West Kingston, RI 02892
	FR Address:		4, rue Ste Claire Deville
				Zac du Mandinet-Batiment Espace
				LOGNES
				77447 MARNE LA VALLEE Cedex 2
				FRANCE
	US & CAN Phone:		1-800-800-4272
	Europe Phone:		(+33) 1.64.62.59.00
	World Wide Phone:	(401) 789-5735
	Email:			apctech@apcc.com
	WWW:			http://www.apcc.com

	UPS Products:
		Smart UPS in sizes up to 2000 VA.  The Smart UPS's do 
		monitoring and can shutdown multiple machines using the
		PowerChute software.  I recommend putting these on 
		computers.  SNMP adaptor can be installed.
		Back UPS same as Smart UPS except that you cannot 
		communicate interactively with the UPS and it will not
		support SNMP.  I recommend putting these on dumb equipment 
		like network equipment, X Terminals and Macintoshes (sorry, 
		I couldn't resist.)	
		Matrix UPS a modular "fault-tolerant" system.  Any
		module, except the insulation unit, can be "hot-swapped" 
		at any time.  Also additional battery modules can be added, 
		again, while the system is running.  SNMP adaptor can be
		installed.
	Software:
		PowerChute, PowerChute PLUS.  They produce it themselves.  
		Supported on:  SunOS, HP-UX, SCO, AIX, AT&T UNIX,
		Interactive UNIX, XENIX, IRIX, and probably others by now.
	Contributed by:
		APC information contributed by Nick Christenson, 
		npc@minotaur.jpl.nasa.gov without consultation with
		APC.  Additional information provided by Joe Moss,
		joe@morton.rain.com.  I have no affiliation with APC 
		except as a satisfied customer.
		Updates contributed by Grant R. Bowman, grantbow@netcom.com.
	------------------------


	Company:		Best Power Technology, Inc.
				P.O. Box 280
				Necedah, WI 54646-9899
	US Phone:		1-800-356-5794
	Email:			None known

	UPS Products:
	FERRUPS:  Ferroresonant-Based, Line-Interactive UPS, sizes 
		from 500 VA - 18 KVA.  
		Features:  Standard power features, serial line
		communications, runtime monitoring, logging, 
		automatic shutdown with optional software, user
		configurable.
	FORTRESS:  Advanced, line-Interactive UPS, sizes from 360 
		VA - 2 KVA.
	PATRIOT:  Low-Cost Standby Power Systems, 250 VA - 850 VA.
	
	Contributed by:  Scott Pinkerton, spinkert@t4rta-gw.den.mmc.com
	------------------------


	Company:                Clary Corporation
        Address:                Clary Corporations
                                320 W Clary Ave
                                San Gabriel, CA 91776
        US Phone:               818 287-6111

        UPS Products:
        I'm not sure of the entire line, but their PC series includes
	[ On-line -npc ] UPS ranging from 400 to 1500 VA [ 450 to 2400 
	VA -npc] with surge and noise suppression.  Voltage regulation 
	to 3%, frequency to 1 Hz, RS232 signal output, LED load and 
	charge indicators.  Sine wave output, Alarm, etc.. 

	[ SW will do shutdown/startup and SNMP for LAN Manager, LAN
	Server, Netware 3.X, 4.X, Unix, VINES, Windows NT, and OS/2. 
	-npc ]

	Contributed by:  Ron Tansky, ron.t@bix.com who has no relation
		to Clary Corporation except as a user.
		Additions by npc from October 1994 issue of LAN Magazine.
	------------------------


	Company:		Controlled Power Company
				1955 Stephenson Hwy.
				Troy, MI 48083
	US Phone:		1-800-521-4792
				1-313-528-3700
	US Fax:			1-313-528-0411

	UPS Products:
		UPS, AC regulators, power conditioners.  They
		will do custom work.

		[ On-line UPS from 400 to 60000 VA.  Software
		with shutdown/startup and SNMP functions for
		AppleShare, LAN Manager, LAN Server, NetWare
		3.X, 4.X, UNIX, VINES and Windows NT -npc ]

	Contact: David Gerds (Sales)

	Contributed by: Donald McLachlan, don@mars.dgrc.doc.ca
		Additions by npc from LAN Magazine, October 1994.
	------------------------


	Company:		Data General

	UPS Products:
		Data General repackages another vendor's UPS's (from
		Exide?) with some sort of special cable.  They deserve 
		some mention since they provide UPS monitoring software 
		built in to the AViiON (their UN*X boxen) line.  It can 
		be managed through sysadm(1M).

	Contributed by:  Morris Galloway Jr., mmgall@presby.edu
	------------------------


	Company:		DELTEC
				2727 Kurtz St.
				San Diego, CA 92110-9980
	US Phone:		1-800-854-2658
	Email:			None known

	UPS Products:
		"Most technologically advanced *true* on-line UPS."
		[ 400 to 2200 VA line-interactive UPS systems.  
		Software with shutdown/startup and SNMP for 
		AppleShare, LAN Manager, LAN Server, NetBIOS,
		NetWare 3.X, 4.X, UNIX, VINES, Windows NT and OS/2. 
		-npc ]

	Contributed by:  Robert D. Freeman, rdf@thermo.chem.okstate.edu
		Additions by npc from October 1994, LAN Magazine.
	------------------------


	Company:		Easy Options IBM Corporation
	Address:		IBM Corporations
				Easy Options
				Dept. WC3J
				P.O. Box 2150
				Atlanta, Ga 30301-9948
	US Phone:		Unknown.
	
	UPS Products:
	UPS ranging from 250 VA to 600 VA with surge and noise suppression.
		Sine wave output, Test/Alarm, etc..
	These UPS's come with an insurance policy.  If your UPS damages
	your systems, they'll pay you up to $25,000.	
	Software:  
	Works with APC's PowerChute software.

	I doubt that IBM is making their own UPS's rather than repackaging
	someone elses, but I'll be glad to post a correction if they are.

	Contributed by: Dave Gruhn, dgruhn@fuzzy.eskimo.com
		who has no relation to IBM, or Easy Options except as
		a satisfied customer.
	------------------------


	Company:		EFI Electronics
	US Phone:		1-801-977-9009
				1-800-877-1174
	
	UPS Products:
		400 to 1250 VA Standby UPS systems.  Software
		with shutdown/startup and SNMP for LAN Manager,
		LAN Server, NetWare 3.X, 4.X, UNIX, VINES, 
		Windows NT.

	Contributed by:  npc, from October 1994 issue of LAN Magazine.
	------------------------


	Company:		Elgar Power Systems Components
				9250 Brown Deer Road
				San Diego, CA 92121
	US Phone:		1-800-733-5427
				1-619-450-0085
	US Fax:			1-619-458-0267

	UPS Products:
		UPS, Line Conditioners, AC regulators.

	Contributed by: Donald McLachlan, don@mars.dgrc.doc.ca
	------------------------


	Company:		Emerson Electric Co., Computer Power Div.
	US Address:		9650 Jeronimo Road
				Irvine, CA 92718, USA
	UK Address:		Elgin Drive, Swindon
				Wiltshire SN2-6DX, England
	FR Address:		8, Rue de l'Esterel
				Silic 502
				94623 Rungis Cedex
				France
	IT Address:		SICE S.p.A. [Note national Name!]
				Via Rossini 6
				20098 San Giuliano Milanese
				Italy
	US Phone:		1-800-BACKUPS
	UK Phone:		+44 458 841898
	FR Phone:		+33 146 862336
	EMail:			n/a

	Products:
        Accupower GOLD Series:
                UPSes for 750, 1000, 1500, 2100 VA, the latter with
                external Batt Pack. Connector for {Power,Accu}Mon S/W.
                5 yr Batt Life. Good Display (3 Status LEDs, Load
                and Batt Charge LED Bargraphs). Switches positioned
                wrong (Main Power Switch on Front, Batt Check/Alarm
                off on Back - I'd prefer them the other Way 'round).
        other UPSes?
        PowerMon Software:
                Triggers for Outage, long Outage, Batt low. Uses one
                serial Connector. Logging and Warnings to Users.
                Requires special Cable (included in PowerMon Kit).
                NOTE: The "Batt low" Trigger does not work "on SunOS
                4.1.1 and above due to OS Limitations". >:-C I don't
                know whether this includes Solaris 2.x.
        AccuMon Software:
                Reported to support all Kinds of fancy Communication
                Items (gathering Power Line and internal UPS Data,
                test Batt Cap periodically and announce Batt Aging,
                switch off UPS on Computer Command, Logging 
		Facilities for all these Functions)
        Other Software?

	Contributed by: Jochen Bern, bern@kleopatra.Uni-Trier.DE
		who has no relation to Emerson.
	------------------------

	
	Company:		Exide
				8521 Six Forks Road
				Raleigh, NC 27615
	US & Canada Phone:	1-800-554-3448
				1-919-872-3020

	UPS Products:
		800 to 1500 VA On-line UPS systems.  Software
		does shutdown/startup and SNMP for NetWare 3.X, 
		4.X, UNIX, VINES, Windows NT
	
	Contributed by: npc from October 1994 LAN Magazine.
	------------------------


	Company:		Gamatronic Electronic Industries Ltd.
				P.O. Box 7369
				Jerusalem 91073
				Israel
	Israel Phone:		972-2-821777
	Israel FAX:		972-2-828875
	Email:			Gamatronic@Product.com
				Goren@Vms.huji.ac.il

	UPS Products:
		250 VA to 750 VA stand-by UPS systems.  On-line
		Smart UPS systems from 250 VA to 80 KVA with
		microprocessor controllers.  Shutdown/startup
		software for LAN manager, Novell, Unix, Windows NT.

	Contributed by: E. Finegold of Gamatronic.
	------------------------


	Company:		Hewlett-Packard

	UPS Products:
		HP used to resell Deltec and APC UPS units.  They
		will discontinue selling these as of April 1, 1995.
		They now have their own line of UPS productcs
		called "PowerWise UPS".

		PowerWise UPS are on-line units and come in 1000 VA 
		and 2100 VA sizes.  Shutdown software is available
		for HP-UX, AIX, Solaris, SCO, UnixWare, Windows NT, 
		NTAS, OS/2, Lanserver and NetWare.

	Contributed by:  Tom Myers, tvmyers@icdc.delcoelect.com
	Updated by:	npc, on information from Hewlett-Packard.
	------------------------


	Company:		Hipotronics Inc.
				Route 22
				Brewster, NY 10509
	US Phone:		1-914-279-8091
	US Fax:			1-914-279-2467

	UPS Products:
		UPS, Line Conditioners, AC Regulators.

	Contributed by: Donald McLachlan, don@mars.dgrc.doc.ca
	------------------------


	Company:		Intellipower
	US Phone:		1-714-587-0155

	UPS Products:
		650 to 1100 VA On-line UPS systems with
		software for shutdown/startup and SNMP for
		AppleShare, LAN Manager, LAN Server, NetWare
		3.X, 4.X, UNIX, VINES, Windows NT, AIUX, 
		NetWareLite, LANtastic

	Contributed by: npc from October 1994 LAN Magazine.
	------------------------


	Company:		Liebert Corportation
				1050 Dearborn Drive
				P.O. Box 29186
				Columbus, OH 43229
	US Phone:		1-614-888-0246
				1-800-877-9222
	US Fax:			1-614-841-6973

	UPS Products:
		250 to 600 VA Standby UPS, 600 to 2000 VA 
		Line-interactive UPS, 750 to 18000 VA On-line
		UPS systems.  Software does shutdown/startup
		and SNMP for AppleShare, LAN Manager, LAN Server,
		NetBIOS, NetWare 3.x, 4.X, UNIX, VINES, 
		Windows NT, OS/2.  Communications interface for
		SGI machines is available.

	Contributed by: George Elkins, elkins@nmrlab.cabm.rutgers.edu
		and npc from LAN Magazine, October 1994.
	------------------------


	Company:		Minuteman
	US Phone:		1-214-446-7363
				1-800-238-7272

	UPS Products:
		300 to 425 VA Standby UPS, 500 to 2000 Line-
		interactive UPS, 500 to 1000 VA On-line UPS.
		Software does SNMP for AppleShare, LAN Manager,
		LAN Server, NetWare 3.X, 4.X, UNIX, VINES,
		Windows NT.

	Contributed by: npc from LAN Magazine, October 1994.
	------------------------


	Company:		Oneac
	US Phone:		1-708-816-6000
				1-800-327-8801

	UPS Products:
		400 to 1800 VA Isolated Line-Interactive UPS
		with software that does shutdown/startup and
		SNMP for LAN Manager, LAN Server, NetWare 3.X,
		4.X, UNIX, VINES and Windows NT systems.

	Contributed by: npc from LAN Magazine, October 1994.
	------------------------


	Company:		Philtek Electronics Ltd.
				2471 Vauxhaul Place
				Richmond, BC
				V6V 1Z5  Canada
	Phone:			1-604-270-4642
	Fax:			1-604-270-8343

	UPS Products:
		UPS's.

	Contact: Bob Smedley

	Contributed by: Donald McLachlan, don@mars.dgrc.doc.ca
	------------------------


	Company:		Pylon Electronic Development
				5020 Fairway St.
				Lachine, PQ
				H8 1B8  Canada
	Phone:			1-514-633-8787
	Fax:			1-514-636-1970

	UPS Products:
		UPS's/Power conditioners, modular/industrial

	Contact: Graeme Turnbull
	
	Contributed by: Donald McLachlan, don@mars.dgrc.doc.ca
	------------------------
		

	Company:		Sola
	
	UPS Products:
		Sola apparently used to repackage Deltec systems.
		They have merged with Best Power Tech to form the
		new Best Power company, a unit of General Signal.

	Contribued by: npc, with updated information from Michael 
		Reget of Best Power.
	------------------------


	Company:		Square D-EPE/TOPAZ
	US Phone:		1-714-557-1636
				1-800-344-0570

	UPS Products:
		250 to 700 VA Standby UPS, 600 to 2000 VA
		Line-interactive UPS, 900 to 10000 On-line
		UPS.  Software does shutdown and SNMP on
		AppleShare, LAN Manager, LAN Server, NetBIOS,
		NetWare 3.X, 4.X, UNIX, VINES, Windows NT,
		OS/2.

	Contributed by: npc from LAN Magazine, October 1994.
	------------------------


	Company:		Superior Electric
	US Phone:		1-203-585-4500

	UPS Products:
		400 to 2200 VA On-line UPS.  Software does
		shutdown/startup on AppleShare, LAN Manager,
		LAN Server, NetWare, UNIX, VINES, Windows NT.

	Contributed by: npc from LAN Magazine, October 1994.
	------------------------


	Company:		Toshiba International Corporation
	US Address:		Industrial Division
				13131 West Little York Rd.
				Houston, TX 77041
	US Phone:		1-713-466-0277
	US Fax:			1-800-321-1412
	Canada Phone:		1-800-527-1204

	UPS Products:
		Single and three phase double conversion on-line UPS,
		from 600 VA to 50 KVA.  Serial line interface and
		auto-shutdown software available.

	Contributed by:  Seth J. Bradley, sbradley@scic.intel.com, 
		a very satisfied customer.
	------------------------


	Company:		Tripp Lite
				500 N. Orleans
				Chicago, IL 60610-4188
	US Phone:		1-312-329-1601
				1-755-5401
	Email:			None known

	UPS Products:
	On-line UPSs with pure Sine Wave output. [ 250 to 1250 VA
	Standby UPS, 250 to 2000 Line-interactive UPS, 300 to
	2000 VA On-line UPS.  Software does shutdown/startup, SNMP
	and RMON for AppleShare, LAN Manager, LAN Server, NetWare,
	UNIX, VINES, Windows NT, OS/2, LANtastic. -npc ]
	
	Contributed by:  Robert D. Freeman, rdf@thermo.chem.okstate.edu
		Additional info by npc from LAN Magazine, October 1994.
	------------------------


	Company:		Waber, Inc.
				(A division of SL Industries, Inc.)

	UPS Products:
	UPS 250, 500.  No other information on this company.

	Contributed by:  npc, from an advertisement for Fry's Electronics
		(of Manhattan Beach, CA) in the October 17, 1994 issue
		of MicroTimes.
		


05.03	Software products:

	Company:		ResponseWare Inc.
	US Phone:		1-800-673-4777
	Email:			responseguy@AOL.com

	Products:
	ResponseWare is software that performs a great number of
	services for UPS users.  ResponseWare uses a MS Windows
	console as its control point.  The console communicates 
	with both a UPS and the server.  It has built-in out call
	paging and they offer a remote monitoring service where 
	they can dial-in, diagnose problems and dispatch help.
	The software also can monitor temperature, humidity,
	security, life/safety, etc..

	ResponseWare works on Novell (NLM), AS/400, HP 9000, Sun,
	and VAX platforms.

	It works with APC, Best, Deltec, Exide, Liebert and TrippLite
	UPS products.

	Cost is $99 per server and $199 for the MS-Windows Console
	program.  Monthly monitoring charges begin at $99/month.

	Information provided by Bob Hunter of ResponseWare provides
	this information.
	------------------------


	On the NeXTSTEP front, there is a company called BenaTong (?)
	which sells a software package called PowerGuardian for NeXTSTEP
	only.  It will work with APC, TrippLite and UNISON UPS's.  If, 
	for example, you call APC and ask for PowerChute for NeXT, they
	will refer you to Power Guardian.

	Contributed by:  Chuck Bennett, (chuck@benatong.com) who works
	for this company.
	------------------------


	Also for NeXTstep, Max Hailperin wrote a package for monitoring
	Best Fortress UPS units called GACUPS.  It consists of a daemon
	and a GUI.  The daemon will shut the NeXT machine down gracefully
	and do logging.  It also answers queries from the GUI.  The GUI
	displays status information.  It should be available on the usual
	NeXTstep anonymous FTP sites.  One place you might want to check
	is in :  ftp://nova.cc.purdue.edu/pub/next/submissions/.  Any
	reports on how it works?

	Contributed by Max Hailperin (max@kolmogorov.gac.edu).




05.04	Other companies:  ITT Power System Corp
			  Digital Equipment Corporation.  (They probably
				repackage someone else's stuff, but 
				they're likely to support it and you
				can order it from their catalog.)

		I'd appreciate any information I can get on these.
		
06:
TOPIC:	Bibliography

	There are many good references and review articles on UPS
	information.  Some of the best sources can be found in 
	vendor information.  There is great reference material woven
	into their propoganda.  Some other good sources are:

	"The Dranetz Field Handbook for Power Quality Analysis",
		1991, Dranetz Technologies, 1000 New Durham Rd., 
		Edison, NJ 08818, 1-908-287-3680.
	"National Electrical Code Handbook", 1993, National Fire
		Protection Association, One Batterymarch Park, 
		P.O. Box 9101, Quincy, MA 02269, 1-617-770-3000.
	"Grounding and Shielding in Facilities", 1990, by Ralph
		Morrison and Warren H. Lewis, John Wiley & Sons,
		New York, ISBN 0-471-83807-1.
	"Battling Power Problems", by Alan Frank, LAN Magazine, 
		October 1994, pp 65-72, Miller Freeman, Inc..
	"UPS Chart", by the LAN staff, LAN Magazine, October
		1994, pp 74-84, Miller Freeman, Inc..
	Hewlett-Packard has a White Paper on selecting a UPS.
		You may be able to get them to send it to you.
		A shortened version appeared as an aritcle in
		the January 9, 1995 issue of Electronic Engineering
		Times.


07:  
TOPIC:  Acknowledgements

	I would like to thank Charles Rhoades (cwr@zeus.jpl.nasa.gov) for
	his sage remarks on my draft of this document.
	I would like to thank Kevin R. Ray (kevin@kray.com) for sending me
	the freely distributable upsd software and Ronald Florence 
	(ron@mlfarm.com) for contributing the pf program. 
	Thanks also to Don Deal (Don.Deal@oit.gatech.edu) for a great
	many valuable suggestions and that great section on the types
	of UPS units.
	The following people have all made valuable contributions to this 
	document:
		Scott Pinkerton, spinkert@t4rta-gw.den.mmc.com
		Morris Galloway Jr., mmgall@presby.edu
		David E A Wilson, david@cs.uow.edu.au
		Edward Hartnett, ejh@larry.gsfc.nasa.gov
		Joe Moss, joe@morton.rain.com
		Kurt Hillig, khillig@chem.lsa.umich.edu
		Robert D. Freeman, rdf@thermo.chem.okstate.edu
		Jochen Bern, bern@kleopatra.Uni-Trier.DE
		Dave Gruhn, dgruhn@fuzzy.eskimo.com
		Steve Welch, smw@columbine.cgd.ucar.edu
		Ron Tansky, ron.t@bix.com
		Andrew J. Templin, nosilla@ohionet.org
		Chuck Bennett, chuck@benatong.com
		M.V.S. Ramanath, ram@sclara.qms.com
		Max Hailperin, max@kolmogorov.gac.edu
		Larry Moss, moss@cvs.rochester.edu

	Please note that I take full blame for any errors or omissions.