If reinforced insulation provides 2 levels of protection, then why assume 2 levels remain after application of a single-fault? The 60950 approach seems to assume that reinforced or double insulation is unaffected by application of a fault.
I consider the approach taken by 61010-1 to be a sensible one. ====================================== Ralph McDiarmid, AScT Compliance Engineering Group Xantrex Technology Inc. From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Brian O'Connell Sent: Wednesday, March 22, 2006 11:15 AM To: emc-p...@ieee.org Subject: RE: Hipot testing following fault testing Which is one of several reasons why I discourage marketing folks from allowing a customer to specify 1010-1 for our units. Note the third conditional in this UL/EN60950-1 clause: 5.3.8.2 After the tests After the tests of 5.3.4 c), 5.3.5, 5.3.6, 5.3.7 and clause C.1, an electric strength test according to 5.2.2 is made on: - REINFORCED INSULATION; and - BASIC INSULATION or SUPPLEMENTARY INSULATION forming part of DOUBLE INSULATION; and - BASIC INSULATION between the PRIMARY CIRCUIT and the protective earthing terminal; if any of the following applies: - the CLEARANCE or CREEPAGE DISTANCE has been reduced below the value specified in 2.10; or - the insulation shows visible signs of damage; or - the insulation cannot be inspected. luck, Brian > -----Original Message----- > From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of Jim > Eichner > Sent: Wednesday, March 22, 2006 9:55 AM > To: emc-p...@ieee.org > Subject: FW: Hipot testing following fault testing > > > Thanks Ralph - good catch. > > So it appears the committee I'm on has come up with an idea > that is not > unique and has precedent in 61010-1. For those interested in this > thread, here's how that standard words the requirement (4.4.4.1(b)): > > 4.4.4 Conformity after application of fault conditions > > 4.4.4.1 Conformity with requirements for protection against electric > shock is checked after the application of single faults as follows: > a) by making the measurements of 6.3.2 to check that no ACCESSIBLE > conductive parts have become HAZARDOUS LIVE; > b) by performing a voltage test on DOUBLE INSULATION or REINFORCED > INSULATION to check that there is still one level of protection by > insulation. The voltage test is made as specified in 6.8 (without > conformity preconditioning) with the test voltage for BASIC > INSULATION. > c) by measuring the temperature of transformer windings if the > protection against electrical HAZARDS is achieved by DOUBLE > INSULATION > or REINFORCED INSULATION within the transformer. The temperatures of > table 16 shall not be exceeded. - 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 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
