Compliance with an immunity regulation is no guarantee that a product will work. It only asserts compliance.
Several years ago, we had a POS product that passed the 16 kV requirements but still failed in the field in the northern states in the winter. Diagnostics indicated that the product failed at 18 kV. The protection was improved to 20 kV and the problem was solved. Bottom line, specs only give an indication of expectations. Your assessment of your environment is the final word. Some members have given some good suggestions on diagnostics. Good luck. Don Umbdenstock Sensormatic > ---------- > From: Douglas C. Smith[SMTP:[email protected]] > Reply To: Douglas C. Smith > Sent: Wednesday, September 08, 1999 1:13 AM > To: Price, Ed > Cc: '[email protected]'; [email protected] > Subject: Re: Immunity Problems ?? > > > 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). > > --------- 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).
