Thanks for the great information. Let me see if I'm comprehending it correctly.
- A product can pass the leakage current test and not pose a hazard to the user but still trip a GFCI. In such cases, is there an alternative to the GFCI? If the NEC requires a GFCI in a location but a device used in that location falsely trips the GFCI, can you wire the instrument without the GFCI and still meet the NEC requirements? (are their exclusions?). Is there something you can do, such as provide an addition safety earth ground connection, instead of the GFCI? If I'm correctly understanding the reason our product is tripping the GFCI, there is nothing we can do about it. So, our only choice is to find an exclusion or an alternate to the GFCI that would satify everyone. Any suggestions would be appreciated. The Other Brian From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of rn...@san.rr.com Sent: Friday, August 17, 2007 2:17 PM To: emc-p...@ieee.org Subject: RE: Ground Fault Circuit Interrupter tripping Hello John: > I've never measured the 'frequency response' (trip current vs. > frequency) of a GFCI (they don't occur in UK, we have RCCBs) but I > suspect that the trip current is higher than the design value at > higher frequencies. As far as I know, there is no frequency compensation in the GFCI. The frequency response is determined by the core characteristics and the IC amplifier characteristics. Virtually all US/Canada GFCIs use the National Semiconductor LM1851 IC. The data sheet includes some good information on GFCI circuits and circuit performance. There are no frequency response specs that I could find. Here is the URL for the LM1851 and data sheet: http://www.national.com/mpf/LM/LM1851.html Here is another web site for GFCI information: http://www.codecheck.com/gfci_principal.htm The original question pointed out that the leakage current was in spec, but the load nevertheless tripped the GFCI. The only conclusion is that the leakage current meter and the GFCI do not have the same measuring circuits -- which they don't. We do know that the leakage current measuring network accounts for the response of the body to frequency, while the GFCI has no such metering circuit network. Best regards, Rich Richard Nute Product Safety Consultant San Diego - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc LECO Corporation Notice: This communication may contain confidential information intended for the named recipient(s) only. If you received this by mistake, please destroy it and notify us of the error. Thank you. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________
