Pete, Your statements may be true for many product types certified to 60950-1, 61010-1, etc. However when dealing with power conversion products that have secondary voltages well above mains voltages, this is no longer true. In the region of 5,000 V and above, corona is a common occurrence in inhomogeneous fields and this has the effect of causing surface damage (carbonization) on insulation with any organic content. Inorganic insulators such as ceramics and glass seem to be much less affected.
Such phenomena is mentioned in Klaus Stimper's book, The Physical Fundamentals of Low-Voltage Insulation Co-ordination. All the best, Doug On Wed, Aug 15, 2018 at 10:04 AM Pete Perkins < 00000061f3f32d0c-dmarc-requ...@ieee.org> wrote: > All, This discussion goes around year after year. > > > > The test results reported – especially Nute – show that it > takes dozens, maybe hundreds of hipot tests to damage adequate > insulation. > > > > In the UK, so I hear, the gov’t safety folks expect each > piece of equipment to be hipot retested annually to demonstrate adequate > insulation. We don’t hear a large hue and cry about failing equipment in > that arena. > > > > So from the experience and the data it is clear that both > the engineering type hipot testing and the factory routine testing should > not pose any problem to properly designed and manufactured products. > > > > For line connected products it is foolishness to remove > components for hipot testing. If that is being done the product is not > robust enough in the first place. This includes DC line powered equipment > since so much DC power is being installed and used in places where it is > subject to the same lighting and starting impulses traditionally seen on AC > line operated equipment. > > > > :>) br, Pete > > > > Peter E Perkins, PE > > Principal Product Safety & Regulatory Affairs Consultant > > PO Box 23427 > > Tigard, ORe 97281-3427 > > > > 503/452-1201 > > > > IEEE Life Fellow > > p.perk...@ieee.org > > > > *From:* Jim Hulbert <jim.hulb...@pb.com> > *Sent:* Wednesday, August 15, 2018 5:25 AM > *To:* EMC-PSTC@LISTSERV.IEEE.ORG > *Subject:* Re: [PSES] hipot test > > > > I disagree with your NRTL. If the hipot test can degrade the insulation > (we’re talking about a single test on the production line), then the > insulation system is not up to par. > > > > Jim > > > > > > *From:* Nyffenegger, Dave [mailto:dave.nyffeneg...@bhemail.com > <dave.nyffeneg...@bhemail.com>] > *Sent:* Wednesday, August 15, 2018 12:18 AM > *To:* EMC-PSTC@LISTSERV.IEEE.ORG > *Subject:* Re: [PSES] hipot test > > > > The NRTL I typically use always runs the hipot test for 60 seconds for > type testing during product certification. The listing reports always > specify a 1 second hipot for production line testing 100% of all units. > Their claim is that the hipot can degrade some insulation and should be > kept to a minimum. > > > > -Dave > > > > *From:* Richard Nute [mailto:ri...@ieee.org <ri...@ieee.org>] > *Sent:* Tuesday, August 14, 2018 5:34 PM > *To:* EMC-PSTC@LISTSERV.IEEE.ORG > *Subject:* [PSES] hipot test > > > > > > Hi Doug: > > > > I've always viewed the purpose of hipot testing as verification only. > During engineering type testing, it is design verification. > > > > I disagree. The hi-pot test determines the minimum electric strength of > the insulation system. Design is an indirect measure of electric strength > by selecting the distances through solid and air (clearance) insulations. > However, design rarely includes the shape of the electric field, which is a > parameter that determines electric strength. > > > > Since hipot is so stressful to insulation… > > > > Again, I disagree. If the design is “good” (adequate electric strength), > then the hi-pot test does not stress the insulation system. See Agilent > Technologies Optocoupler Input-Output Endurance Voltage Application Note > 1074. > > > > Best regards, > > Rich > > > > > > > > *From:* Doug Powell <doug...@gmail.com> > *Sent:* Tuesday, August 14, 2018 1:50 PM > *To:* EMC-PSTC@LISTSERV.IEEE.ORG > *Subject:* Re: [PSES] X & Y Cap rating due to hipot test > > > > I've always viewed the purpose of hipot testing as verification only. > During engineering type testing, it is design verification. During routine > testing for manufacturing, it is workmanship and build verification. > > > > During type testing many safety standards will ask for hipot verification > at various stages, after thermal/humidity tests, after abnormal operations, > etc. Since hipot is so stressful to insulation, it is possible to > introduce latent failures in the test sample after performing multiple > hipot tests, combining many hipots into one is allowable by many > inspectors. > > > > During routine testing, a brief hipot is added at the end of the > manufacturing cycle to ensure wire routing is correct (spacings are > maintained), integrity of insulation is maintained, in cases where > vibration testing is involved a test for chafing of wire insulation and so > on. Most safety standards have provision for "allowable disconnects" > during the hipot such as surge suppressors and the like. Also, hipot of > sub-assemblies in lieu of the finished assembly if it can be shown that the > test is representative. > > > > Best to all, Doug > > > > -- > > > > Douglas E Powell > > doug...@gmail.com > http://www.linkedin.com/in/dougp01 > > > > - > ---------------------------------------------------------------- > > 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) <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> > Mike Cantwell <mcantw...@ieee.org> > > For policy questions, send mail to: > Jim Bacher <j.bac...@ieee.org> > David Heald <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) <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> > Mike Cantwell <mcantw...@ieee.org> > > For policy questions, send mail to: > Jim Bacher <j.bac...@ieee.org> > David Heald <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) <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> > Mike Cantwell <mcantw...@ieee.org> > > For policy questions, send mail to: > Jim Bacher <j.bac...@ieee.org> > David Heald <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) <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> > Mike Cantwell <mcantw...@ieee.org> > > For policy questions, send mail to: > Jim Bacher <j.bac...@ieee.org> > David Heald <dhe...@gmail.com> > -- Douglas E Powell doug...@gmail.com http://www.linkedin.com/in/dougp01 - ---------------------------------------------------------------- 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>
