Hi All, ESD or EFT could be the culprit. I would suggest putting a current probe around one of the instrument cables and connect to a digital scope and see if you can trigger on a noise event. If you are lucky, the instrument with the current probe will be the one that goes down.
Alternatively, connect a small antenna to the scope, set to 50 Ohm input, set the V scale to 100 mV/div, H to 20 ns/div, and trigger on a 50 mV positive going edge for starters. If you get nothing or too much, adjust the parameters accordingly. A 6 inch diameter loop of wire makes a good antenna. Doug "Price, Ed" wrote: > > Joe wrote: > > -----Original Message----- > From: [email protected] [SMTP:[email protected]] > Sent: Tuesday, September 07, 1999 2:04 PM > To: [email protected] > Cc: [email protected] > Subject: Immunity Problems ?? > > >EMC Professionals, > > >We have 42 of the same instruments installed in one laboratory. > > What are they? What type of power feeds and I/O lines or sensors? > What about physical separation? > > >They are each installed on their own dedicated line. > > Powerline? > > >On a regular basis > > The toughest problems are unpredictable, intermittent failures. This > is your first ray of hope; you should try to associate the problem with > external conditions; i.e., a step in your process, the plant elevator, the > air conditioning, every 107 minutes, something. > > >an instrument will shut down during a run. > > A bit more description about the "shutdown." > > >The instrument that shuts down is different each time. > > Really, NEVER the same instrument? Or do you just mean it strikes > randomly? > > >These instruments are laboratory equipment that meet Class A > radiated limits of > >EN 55011 and meet the immunity requirements of EN 50082-1. > > So, then you really don't have a problem? (Sorry, grin!) > > >Any ideas as to the potential cause of the problem and possible > ways to resolve > >the problem would be greatly appreciated. > > Well, you can start right away with the correlation effort. You > could also put a powerline monitor on the power buss. If you operated one > instrument without I/O or data or control leads, you might start to get an > idea about the problem if that one instrument NEVER shutdown. That might say > the problem is not coupled through the power bus. OTOH, if it failed just as > the others, that may lend weight toward the power bus as the path. > > Can you operate an instrument in another building? Do you get zero > shutdowns, or the same probability? Can you operate a cluster of your > instruments in a remote location, and do they exhibit shutdown problems too? > > >Regards > > >Joe Martin > >EMC/Product Safety Engineer > >P.E. Biosystems > >[email protected] > > That's enough for now! Organize your info and get back to the list. > > Regards, > > Ed > > :-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-) > Ed Price > [email protected] > Electromagnetic Compatibility Lab > Cubic Defense Systems > San Diego, CA. USA > 619-505-2780 (Voice) > 619-505-1502 (Fax) > Military & Avionics EMC Services Is Our Specialty > Shake-Bake-Shock - Metrology - Reliability Analysis > :-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-) > > --------- > This message is coming from the emc-pstc discussion list. > To cancel your subscription, send mail to [email protected] > with the single line: "unsubscribe emc-pstc" (without the > quotes). For help, send mail to [email protected], > [email protected], [email protected], or > [email protected] (the list administrators). -- ----------------------------------------------------------- ___ _ Doug Smith \ / ) P.O. Box 1457 ========= Los Gatos, CA 95031-1457 _ / \ / \ _ TEL/FAX: 408-356-4186/358-3799 / /\ \ ] / /\ \ Mobile: 408-858-4528 | q-----( ) | o | Email: [email protected] \ _ / ] \ _ / Website: http://www.dsmith.org ----------------------------------------------------------- --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
