Powerline noise problems

[WestexJoe]

Hello,
We've been experiencing quite a few electronic equipment failures. I've
never seen so many variable DC bench supplies go south in my 25+ years
of repair and R&D. Our operations range from microwave transmitters to
MIG welding. Everytime I've hung a 'scope or spectrum analyzer on the
AC, everything looks fine. I'm suspecting random events on the
powermains are the root of our problems.
Can anyone reccommend a good power analyzer that could catch random
spurs and fluctuations?
Thanks,
WestexJoe

 

[Rich Grise]

On Monday 04 October 2004 05:58 pm, WestexJoe did deign to grace us with the
following:

Can anyone reccommend a good power analyzer that could catch random
spurs and fluctuations?

Probably the power company. Call them and ask. The worst they can do is say
"No."

Good Luck!
Rich

 

[Joerg]

Hi Rich,

Can anyone reccommend a good power analyzer that could catch random
spurs and fluctuations?



Probably the power company. Call them and ask. The worst they can do is say
"No."


They usually don't refuse. When I suspected such a problem they came out

within a few days and hooked up a long term monitor. Later they showed
me the plots. To me they looked rather horrifying but they said it's
"normal". Anyway, for some reason the voltage fluctuations lessened and
the average number of light bulbs we blew went from several a week to
one every other months.

Regards, Joerg

http://www.analogconsultants.com

 

[Joerg]

Hi Joe,

Since you email address is Budweiser, maybe there are some larger
transients coming from production equipment? Large motors, elevators
etc.? Did they install a big new production line?

Best would be to hook up a long term recorder, either an older strip
chart type or a RAM based one. The utility has these. They work similar
to the Holter EKG units that monitor your heart 24 hours to catch an
occasional arrhythmia if it is suspected.

Regards, Joerg

http://www.analogconsultants.com

 

[legg]

On Tue, 05 Oct 2004 00:58:29 GMT, WestexJoe <westexjoe@budweiser.com>
wrote:

Hello,
We've been experiencing quite a few electronic equipment failures. I've
never seen so many variable DC bench supplies go south in my 25+ years
of repair and R&D. Our operations range from microwave transmitters to
MIG welding. Everytime I've hung a 'scope or spectrum analyzer on the
AC, everything looks fine. I'm suspecting random events on the
powermains are the root of our problems.
Can anyone reccommend a good power analyzer that could catch random
spurs and fluctuations?

Any specific brand or model number? Any recent purchases?

If you suspect line fluctuations, you might try to synchronize your
monitoring with specific work-site events -

Start of workday or shift. (lights-on, compressors starting,
Start of burn-in loading (if employed at your site).
Start of DVT (shake and bake).
Duration of typical production test interval.

Monitoring should be performed at the location where device failure
has been reported.

Has any work to 'upgrade' capacity occured recently?

RL

 

[Rich Grise]

On Tuesday 05 October 2004 02:40 pm, Joerg did deign to grace us with the
following:

Hi Rich,

Can anyone reccommend a good power analyzer that could catch random
spurs and fluctuations?



Probably the power company. Call them and ask. The worst they can do is
say "No."


They usually don't refuse. When I suspected such a problem they came out
within a few days and hooked up a long term monitor. Later they showed
me the plots. To me they looked rather horrifying but they said it's
"normal". Anyway, for some reason the voltage fluctuations lessened and
the average number of light bulbs we blew went from several a week to
one every other months.

Sounds like they found and fixed the problem, but it was so stupid that

they didn't want to admit it.

Cheers!
Rich

 

[Joerg]

Hi Joe,

... (Except the assumption that I work at Budweiser, it's avionics)...

Well, your first post had "budweiser.com" in the email address. Wish it

would have been some local brew, but...

Having repaired several of these units, I am finding some shorted 2kV caps
on the AC input.

That speaks for transients. Really big ones.

What I am really looking for are some affordable battery powered
data loggers that could cover DC to 300gHz to monitor the power at various
locations and periodically do data dumps. Our operations also involve
portable generators, similiar problems there too.
We're tempted to build some ourselves, but squeezing resources out of
management for something like that is probably not gonna happen.


I don't think you need to go into the GHz range, or even past several

MHz for that matter. But anyway, you can rent these. Browse through a
list like this one:

http://www.telogyinc.com/sm.asp

When you mentioned generators and similar problems there, does that mean
isolated from the grid? If so, is there any major radar installation in
your area? It might pay off to also rent a spectrum analyzer that does
go into the GHz range and just run it in sniffer mode where it stores
shots if something reaches a threshold. Must be run with wide bandwidth
and full scan speed if you think it might be a big radar or something.
It would have to be able to do time stamping.

Regards, Joerg

http://www.analogconsultants.com