A UPS -- RFI question

H

Haines Brown

Guest
I have an old UPS that supports my computer and monitor (55%
load). When I print from my laser printer, which is on the same
outlet, but not plugged into the UPS), the UPS switches itself off,
and of course, my computer crashes.

I removed the UPS and experimented with a lamp, and the UPS worked
fine. It kept the lamp (15% load) running even when the UPS was
disconnected from the line. However, if I try this using an old sparky
hand drill as load (also 15%), when I pull the UPS' own power plug, it
shuts itself down and has to be restarted by toggling the power
switch.

I believe I've eliminated the issue of load by reproducing the problem
under lighter load conditions. Also, the only connection between the
UPS and the printer is that they are on the same circuit. If the
printer pulled the circuit voltage down, handling that situation is
what a UPS is designed for.

My theory is that RFI is the culprit, but I assume the UPS (a very old
Best Fortress) should filter out the RFI. If it is unable to do that,
there's no point of thinking about a ferrite choke on the printer
power line.

Anyone have any ideas on this? Does a (fairly new Lexmark) laser
printer likely have dirty line output? Is a UPS supposed to filer such
trash? Do filters age and become ineffective?
--
Haines Brown
brownh@hartford-hwp.com
kb1grm@arrl.net
www.hartford-hwp.com
 
"Haines Brown" <brownh@langhans.hartford-hwp.com> wrote in message
news:m3ekx8ir24.fsf@langhans.hartford-hwp.com...
I have an old UPS that supports my computer and monitor (55%
load). When I print from my laser printer, which is on the same
outlet, but not plugged into the UPS), the UPS switches itself off,
and of course, my computer crashes.

I removed the UPS and experimented with a lamp, and the UPS worked
fine. It kept the lamp (15% load) running even when the UPS was
disconnected from the line. However, if I try this using an old sparky
hand drill as load (also 15%), when I pull the UPS' own power plug, it
shuts itself down and has to be restarted by toggling the power
switch.

I believe I've eliminated the issue of load by reproducing the problem
under lighter load conditions. Also, the only connection between the
UPS and the printer is that they are on the same circuit. If the
printer pulled the circuit voltage down, handling that situation is
what a UPS is designed for.

My theory is that RFI is the culprit, but I assume the UPS (a very old
Best Fortress) should filter out the RFI. If it is unable to do that,
there's no point of thinking about a ferrite choke on the printer
power line.

Anyone have any ideas on this? Does a (fairly new Lexmark) laser
printer likely have dirty line output? Is a UPS supposed to filer such
trash? Do filters age and become ineffective?
--
Haines Brown
brownh@hartford-hwp.com
kb1grm@arrl.net
www.hartford-hwp.com
Click to expand...
Haines, how is this UPS? Eventually, the IC's go bad. The average run life
of an UPS is ten years. and that is if you have preventive and planned
maintenance done! Let me contemplate on this for a quick minute and get
back to you. By the way that's what I do for a living, please visit our
website:http://www.elysium-inc.com/
 
"SHAUN" <camba850@bellsouth.net> writes:

"Haines Brown" <brownh@langhans.hartford-hwp.com> wrote in message
news:m3ekx8ir24.fsf@langhans.hartford-hwp.com...
I have an old UPS that supports my computer and monitor (55%
load). When I print from my laser printer, which is on the same
outlet, but not plugged into the UPS), the UPS switches itself
off, and of course, my computer crashes.

Haines, how is this UPS? Eventually, the IC's go bad. The average
run life of an UPS is ten years. and that is if you have preventive
and planned maintenance done!
Click to expand...
It's not as old as I thought. Purchased it in May 96, so that makes it
over seven years old. I'm surprised the ICs would deteriorate in that
time, but based on your estimations, it appears to have reached the
end of its life. I just assumed it would last forever. I put
(expensive) batteries in a couple years ago. I can probably find some
good use for them, although they are getting old by this time, too.

Let me contemplate on this for a quick minute and get back to you.
By the way that's what I do for a living, please visit our
website:http://www.elysium-inc.com/
Click to expand...
Thanks, but don't get back by e-mail. My system is
disfunctional. Within three weeks I had mouse finally go, hard disk go
south (an expensive SCSI, which I may be able to get replaced under
warranty), video card (nVidia, the second time I've replaced that card
under warrantee), and now, some three weeks later, my UPS. On top of
that, I can't get my e-mail working :-(

--
Haines Brown
brownh@hartford-hwp.com
kb1grm@arrl.net
www.hartford-hwp.com
 
I have a small 500va monster power UPS and if I get any 440Mhz type
radios near it it starts to beep then will shut down if I do not remove
the RF, 1 type of radio is a handheld motorola bussiness band 450Mhz
radio about 2-5 watts output and it does this within 2-3 feet of the
ups, the other is a low end cobra FRS radio about a foot from the UPS, I
have also just found out my 2.4 Ghz spread spectrum vtech cordless
phones will do the same thing if brought to within a foot of the UPS.

I figure what is happening is that the UPS is seeing the RF and it is
messing up the 60 cycle so the UPS thinks the incoming power is dirty
and shuts down the input.

On Sun, 19 Oct 2003 22:26:58 GMT, Haines Brown
<brownh@langhans.hartford-hwp.com> wrote:

I have an old UPS that supports my computer and monitor (55%
load). When I print from my laser printer, which is on the same
outlet, but not plugged into the UPS), the UPS switches itself off,
and of course, my computer crashes.

I removed the UPS and experimented with a lamp, and the UPS worked
fine. It kept the lamp (15% load) running even when the UPS was
disconnected from the line. However, if I try this using an old sparky
hand drill as load (also 15%), when I pull the UPS' own power plug, it
shuts itself down and has to be restarted by toggling the power
switch.

I believe I've eliminated the issue of load by reproducing the problem
under lighter load conditions. Also, the only connection between the
UPS and the printer is that they are on the same circuit. If the
printer pulled the circuit voltage down, handling that situation is
what a UPS is designed for.

My theory is that RFI is the culprit, but I assume the UPS (a very old
Best Fortress) should filter out the RFI. If it is unable to do that,
there's no point of thinking about a ferrite choke on the printer
power line.

Anyone have any ideas on this? Does a (fairly new Lexmark) laser
printer likely have dirty line output? Is a UPS supposed to filer such
trash? Do filters age and become ineffective?
Click to expand...
REMOVE the NOCRAP in my address to reply.
 
Len <Len.C@sympNOCRAPatico.ca> writes:

I have a small 500va monster power UPS and if I get any 440Mhz type
radios near it it starts to beep then will shut down if I do not remove
the RF, 1 type of radio is a handheld motorola bussiness band 450Mhz
radio about 2-5 watts output and it does this within 2-3 feet of the
ups, the other is a low end cobra FRS radio about a foot from the UPS, I
have also just found out my 2.4 Ghz spread spectrum vtech cordless
phones will do the same thing if brought to within a foot of the UPS.

I figure what is happening is that the UPS is seeing the RF and it is
messing up the 60 cycle so the UPS thinks the incoming power is dirty
and shuts down the input.
Click to expand...
Len, very interesting. I was not too impressed by my RFI theory, but
your examples lend a little credibility. A QRP transmitter a couple
feet away is not putting much RF into the power line, while my printer
is directly connected to it, and might indeed generate more. If this
is so, I'll find some discussion of it by googling, I'm sure.

I don't know the quality of your UPS, but I assume that quality has
got something to do with RF sensitivity.

I do see on line that laser printers are susceptible to EMF and RFI
interference, and for that reason cables are shielded. However, I'm
speaking here of interference in the other direction.
--
Haines Brown
brownh@hartford-hwp.com
kb1grm@arrl.net
www.hartford-hwp.com
 
Haines wrote
It's not as old as I thought. Purchased it in May 96, so that makes it
over seven years old. I'm surprised the ICs would deteriorate in that
time, but based on your estimations, it appears to have reached the
end of its life. I just assumed it would last forever. I put
(expensive) batteries in a couple years ago. I can probably find some
good use for them, although they are getting old by this time, too.

Shaun wrote:
Let me contemplate on this for a quick minute and get back to you.
By the way that's what I do for a living, please visit our
website:http://www.elysium-inc.com/

Thanks, but don't get back by e-mail. My system is
disfunctional. Within three weeks I had mouse finally go, hard disk go
south (an expensive SCSI, which I may be able to get replaced under
warranty), video card (nVidia, the second time I've replaced that card
under warrantee), and now, some three weeks later, my UPS. On top of
that, I can't get my e-mail working :-(

-- Shaun writes:
Oh don't worry, I meant I will be posting an answer to the group for you.
Click to expand...
Can you give me the specs on it I am working on finding you a solution right
now. Also I may be able to get you an APC or Toshiba for a great price! and
have shipped to you or installed for you!
>
 
"Haines Brown" <brownh@langhans.hartford-hwp.com> wrote in message
news:m3ekx8ir24.fsf@langhans.hartford-hwp.com...
I have an old UPS that supports my computer and monitor (55%
load). When I print from my laser printer, which is on the same
outlet, but not plugged into the UPS), the UPS switches itself off,
and of course, my computer crashes.

snip
Haines Brown
Click to expand...
I do not have a real knowledge about UPS devices, but I once noticed a
similar thing with linear regulators and it quite possible to assume that
some of their kind are used in the control electronics os a UPS. Sometimes a
regulator will fail when an IF or HF signal is somehow fed into its output.
The time I noticed it first, I was connecting a digital voltmeter to a
simple device powered through a linear regulator (no idea which, it was two
years ago) and when the voltmeter was connected a HF signal from its
electronics caused the regulator to almost completely switch off. The
voltage was supposed to be 5V, but it turned out to be no more than one (no,
it was not a current meter). Placing a small capacitor in parallel to this
troublesome voltmeter did however solve the problem. Consider placing a
small filter of 2 capacitors with less than 0.5 microfarads each and two
inductors (a dozen of windings on a toroid core) in the power input of the
printer to prevent HF from exiting.


---x---\/\/\---x---
| |
--- ---
--- ---
| |
---x---\/\/\---x---


Note also that some UPS devices immediately shut down when they detect an
'earth fault', an event very easy to trip when both the PC and the printer
are grounded, but over separate grounds. In this case, disconnect the
printer's separate ground connection from where it is connected now and
connect it via one of the screws that hold the metal case of the PC's power
supply in place.

Dimitrij
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top