mcohen@nrtc.northrop.com (Marty Cohen) (10/13/88)
I am interested in getting power fail protection for my Amiga. The 2 types are ups - uninterruptable power supply - and sps - standby power supply. A ups takes line current, converts it to dc, stores it in a battery, gets dc from the battery, and converts the dc to ac for whatever needs it. A sps has a battery it keeps charged, but just passes the line current along (possibly with some filtering). When the sps detects that the line current has failed, it switches to its battery before (we hope) the computer crashes. In general, a sps with a given capacity is significantly cheaper than a ups with the same capacity. Questions: 1. Can the Amiga, its monitor, and attached floppy and hard drives use a sps, or is a ups needed? 2. If a sps can be used, how quickly must it switch from line to its internal power. 3. How powerful does the sps or ups need to be for my setup: Amiga 1000, insider with 1 meg, 1080 monitor, C.Ltd. scsi controller, 50 meg hard disk? Thanks, Marty Cohen (mcohen@nrtc.northrop.com, 128.99.0.1)
thad@cup.portal.com (Thad Thad Floryan) (10/16/88)
Re: the question about UPS (Uninterruptible Power Supply) or SPS (Standby
Power Supply) for the Amiga, I'll describe what I'm using for all my Amiga
and AT&T 3B1 UNIXpc systems: a backup power system.
Considering the average of one major power glitch a month in this area (the
hills overlooking Silicon Valley), I consider power protection essential; I
don't mind entering a megabyte-sized program once, but twice is painful.
Just this past Thursday I had a line go down for 67 minutes. Eerie feeling
basking in the soft glow of the Amiga monitor while I'm happily coding away
under candlelight at 3AM. :-)
My lab system comprises an Amiga A1000, with a Ronin Hurricane 68020/68881
card and 4MB 32-bit-wide RAM, along with a 2MB ComSpec AX2000, a Supra 4x4
SCSI host adapter feeding 10 disk drives (two Maxtor XT-3380, one Maxtor
XT-3280, one Maxtor XT-2190 with Adaptec 4000A, a Seagate ST-157N, a Fujitsu
M2451A 190MB tape drive, and assorted other drives connected to various
Adaptec 4000A and 4070 SCSI:ST506/412 translators), an Escort 2 2MB RAM card,
an ARK 24K MNP modem, an Amiga A1070 monitor, and two external A1010 floppies.
Yes, all that equipment continued to operate during the power outage. And, in
fact, the equipment is still up continuously 24 hours/day; haven't even powered
down to install AmigaDOS Enhancer 1.3 which arrived at dealers this past week.
I'm not attempting to brag about the system; I consider that equipment essential
for my work.
The point is, the UPS systems I'm using provide power to sustain the Amigas and
the flanking 3B1 systems.
My requirements were straightforward: sine wave power, no service loss, and
reliability. Fortunately, what I found was also (relatively) inexpensive.
What I'm using are the Safe Model 500 Backup Power Systems. These are American
made by:
Safe Power Systems, Inc.
528 West 21st Street
Tempe, Arizona 85282 602/894-6864, 800/325-5848
I purchased mine from the son-in-law of a long-time buddy of mine from the
Electronic Defense Labs whose company is:
Powersafe
108 E. Fremont Avenue #243
Sunnyvale, California 84087-3201 408/773-1220
The pertinent specifications of the Safe Model 500 are:
Output power rating
Continuous 500 Watts
Surge 1000 Watts
Output current rating 4.4 Amps continuous
Output voltage: 115VAC +/- 3.0%
Output frequency: 60 Hz +/- 1.0%
Output waveform: sinewave, less than 5% THD @ full power
Switchover: synchronized to AC power, both ON and OFF,
less than 1 millisecond
These units ALSO provide COMPLETE transient suppression, and over- and under-
voltage protection.
I can now turn on inductive motors, flourescent lamps, vacuum cleaners, ultra-
sonic welders, etc. with impunity and NO perturbation of the computers or their
disk drives or modems.
Safe Power also manufactures larger capacity units, some of which even have
special signal cables with which to alert one's UNIX systems to the standby
power condition (and initiate a graceful shutdown after some time period).
I wouldn't even consider operating without such a unit (esp. a UNIX system).
Shop carefully for whatever system you eventually choose; some of the products
on the market are junk, providing square wave output and very poor regulation
and inadequate and unsynchronized switchover.
The list price of the Safe Power Model 500 was around $750 several years ago.
Figure you need one UPS for each computer.
With UPS power systems, you DO get what you pay for. Be leery of the $200
units.
A simple test to perform is to see how long a 100W lamp will endure using the
inexpensive units. Note that I said ``ENDURE''. The cheap units will BURN OUT
your equipment (due to square waves, frequency variation, etc.)
Hope this provides a starting point for your UPS/SPS quest!
I also have a 2KW generator backing up everything else. This comes in handy
during the prolonged outages (longest was 6 days when a winter storm carried
one of my 100' eucalyptus trees 30 feet, taking the power and phone lines
with it).
Thad Floryan [ thad@cup.portal.com (OR) ..!sun!portal!cup.portal.com!thad ]thad@cup.portal.com (Thad Floryan) (10/16/88)
I neglected to mention how to correctly test UPS (and similar) systems:
*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*
H H
* I M P O R T A N T *
H H
* The CORRECT way to test a UPS with your equipment is to plug *
H the UPS into a switchable power strip. Turn the switch OFF to H
* test the UPS. This way the safety ground (the third prong on *
H your power plugs and strips) is maintained. H
*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*
Simply unplugging a UPS from the power mains is a HAZARDOUS venture since
you LOSE the protective ground.
To borrow and paraphrase a quote from someone else: "Don't test electrical
equipment by yourself at 3:00 AM. Have a buddy there to laugh his ass off
when you get thrown across the room."
Thad Floryan [ thad@cup.portal.com (OR) ..!sun!portal!cup.portal.com!thad ]MJB@cup.portal.com (Martin J Brown-Jr) (10/18/88)
Have you also noticed the great number of companies/outlets advertising UPS's
with switchover times?!! These are mutually exclusive! watchout!
- MJB -