Hi, Jon. Switching a contactor or relay coil does involve an inrush current and inductive kickback, as previously mentioned. This can affect air gap contacts in significant ways.
For solid state switching, I’m less familiar with the ins and outs, but if you look at some SSR manufacturers’ web sites, you can see that there are different P/Ns within a family of SSRs, depending on the nature of the switched load. For example, use http://www.crydom.com/en/tools/parametric-search.shtml?type=panel to go through some examples. Also, check out (not very detailed, but it gives a flavor) http://www.eaton.com/ecm/idcplg?IdcService=GET_FILE&allowInterrupt=1&RevisionSelectionMethod=LatestReleased&noSaveAs=0&Rendition=Primary&dDocName=AP04901001E There are bound to be some snubbing features built into these SSRs, just as there would be for an electromechanical relay. A lot of SSRs are zero crossing types to prevent switching on higher voltages. This can prolong the life of the SSR. It could simply be clever marketing to change a P/N, but it might also be that there’s a physical difference in the SSRs that make them better suited to certain types of loads. It may be that your design satisfies all of the necessaries for piloting a contactor of a certain VA rating. An NRTL will likely want to do some testing to satisfy themselves that the special concerns are met by your design. If your company is not planning to sell the solid state switch, you can probably negotiate a reduced test program based on your application. If you do negotiate, make sure you build in some head room for load changes so you don’t have to repeat testing when someone gets a clever idea for how to repurpose your design. Regards, Peter Tarver From: Richard Nute [mailto:ri...@ieee.org] Sent: Friday, December 08, 2017 13:09 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Pilot rating The ultimate issue is what safety issue occurs if the contactor fails to open or close when it is supposed to? If there is no safety consequence, then the contactor control is functional, not a safeguard. If there is a safety consequence, then the circuits controlling the contactor constitute a safeguard and must be “reliable,” and must meet the intent of the standard. Not so cynical Rich From: Jon Keeble [mailto:j...@wattwatchers.com.au] Sent: Thursday, December 7, 2017 12:29 PM To: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG> Subject: [PSES] Pilot rating I am using a Panasonic AQH3213A PhotoMOS optical isolator to control a small contactor. At 110VAC the contactor coil draws 30mArms. The coil contacts are wired to a PCB via a terminal block plug and socket. On the PCB is a series 10ohm fusible resistor, and a SMBJ400AC bidirectional zener. When the switch opens at peak current (42mA) there is 0.1J of energy in the coil that gets absorbed by the zener. The zener * clamps at a voltage way below the voltage rating of the optoMOS switch. * is rated at 600W for 8.3msec and is subject to only 13W for a similar period. The UL test engineer says that the optoMOS should be "pilot duty" rated (the part I am using does have this rating). Does anyone know what triggers the requirement for a "pilot duty" rating? Is this defined in a standard somewhere? This useful link identifies "contact rating codes" https://na.industrial.panasonic.com/blog/what-pilot-duty-rating-how-it-obtained The lowest rating E300 is for 110V 1.8A (make) 0.3A (break) Technically speaking, my switch is not connected to the contactor .. there is a two-component network in between Does UL have the capacity or procedures in place to understand and accept a circtuit analysis that shows my circuit as safe? Jon Keeble Wattwatchers. - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org<mailto:emc-p...@ieee.org>> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe)<http://www.ieee-pses.org/list.html> List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org<mailto:sdoug...@ieee.org>> Mike Cantwell <mcantw...@ieee.org<mailto:mcantw...@ieee.org>> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org<mailto:j.bac...@ieee.org>> David Heald <dhe...@gmail.com<mailto:dhe...@gmail.com>> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org<mailto:emc-p...@ieee.org>> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe)<http://www.ieee-pses.org/list.html> List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org<mailto:sdoug...@ieee.org>> Mike Cantwell <mcantw...@ieee.org<mailto:mcantw...@ieee.org>> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org<mailto:j.bac...@ieee.org>> David Heald <dhe...@gmail.com<mailto:dhe...@gmail.com>> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
