Ken, I agree. But there is a lot of equipment being provided in a DC operated environment where the nuisance transients exist. I'm thinking, for instance, of Solar and Wind-power installations which are often remote and self-power all of the control and transmission equipment off of the exposed internal DC power. Hence my statement.
:>) 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 <mailto:p.perk...@ieee.org> p.perk...@ieee.org From: Ken Javor <ken.ja...@emccompliance.com> Sent: Wednesday, August 15, 2018 9:34 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] hipot test There is a huge difference between a transient lasting microseconds and a dc application. The cap will load (to some extent) a transient, but it can't load dc. Ken Javor Phone: (256) 650-5261 _____ From: Pete Perkins <00000061f3f32d0c-dmarc-requ...@ieee.org <mailto:00000061f3f32d0c-dmarc-requ...@ieee.org> > Reply-To: Pete Perkins <peperkin...@cs.com <mailto:peperkin...@cs.com> > Date: Wed, 15 Aug 2018 09:03:57 -0700 To: <EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> > Subject: Re: [PSES] hipot test 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 <mailto:p.perk...@ieee.org> <mailto:p.perk...@ieee.org> <mailto:p.perk...@ieee.org> From: Jim Hulbert <jim.hulb...@pb.com <mailto:jim.hulb...@pb.com> > Sent: Wednesday, August 15, 2018 5:25 AM To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto: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] Sent: Wednesday, August 15, 2018 12:18 AM To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto: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] Sent: Tuesday, August 14, 2018 5:34 PM To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto: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 <mailto:doug...@gmail.com> > Sent: Tuesday, August 14, 2018 1:50 PM To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto: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 <mailto:doug...@gmail.com> http://www.linkedin.com/in/dougp01 - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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