Hello Brian, I have run into a similar problem. The VFD is generating harmonics which are likely causing additional leakage current. If your product's leakage current is due to Y-capacitors, you may have had a clean power source. In one situation, I had a product that significantly increased leakage current if the power was not clean. As the frequency of the harmonics increased, the impedance of the Y-capacitor dropped. Although the energy content of the higher harmonics decreased significantly, the Y-capacitor allowed additional current to flow resulting in a total leakage current high enough to trip a GFCI. I found the susceptibility to this problem to be closely related to the power source for my product.
The problem may not even be due to harmonics in your product. If the power in general is not very clean, the harmonics will generate excessive leakage current through your Y-capacitors. The GFCI may not be falsely tripping. If possible, make a measurement of the actual leakage current at the installation where you have the problem. Ted Eckert American Power Conversion/MGE http://www.apc.com/ The items contained in this e-mail reflect the personal opinions of the writer and are only provided for the assistance of the reader. The writer is not speaking in an official capacity for APC-MGE or Schneider Electric. The speaker does not represent APC-MGE's or Schneider Electric's official position on any matter. "Kunde, Brian" <brian_kunde@leco tc.com> To Sent by: "EMC PSTC" <[email protected]> [email protected] cc Subject 08/15/2007 08:40 Ground Fault Circuit Interrupter AM tripping Some of our customers want to use a GFCI with one of our products which has a frequency drive that runs a 1hp motor. When this motor starts up the GFCI opens. We don't think the problem is with leakage for our leakage current tester is measuring less than 1mA. We are thinking that the GFI is falsely tripping due to low frequency conducted emissions caused by the frequency drive. Can anyone recommend a manufacturer of GFCI that would be more immune to such false trips? Our product can run at both 115VAC or 230VAC. What else could be causing the GFCI to trip that we are not thinking about? Thanks, The Other Brian 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 [email protected] 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 [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc - 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 [email protected] 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 [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] 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 ______________________________________________________________________
