My interpretation of the rationale is from my 60335 experience. The idea is the same as Mold Stress testing. When molded, Polymeric materials have stress lines/points in them. The temperature exposure relieves these stresses which can move the material. The temperature is higher for polymeric parts supporting live parts vs an enclosure. We're looking for reduction of spacings, openings that allow the finger probe, etc. Following is from IEC60335-1, 4th Edition........
30.1 External parts of non-metallic material, parts of insulating material supporting LIVE PARTS including connections, and parts of thermoplastic material providing SUPPLEMENTARY INSULATION or REINFORCED INSULATION, shall be sufficiently resistant to heat if their deterioration could cause the appliance to fail to comply with this standard. This requirement does not apply to the insulation or sheath of flexible cords or internal wiring. Compliance is checked by subjecting the relevant part to the ball-pressure test of IEC 60695-10-2. The test is carried out at a temperature of 40°C ± 2°C plus the maximum temperature rise determined during the test of clause 11, but it shall be at least: – 75 °C ± 2°C, for external parts – 125 °C ± 2°C, for parts supporting LIVE PARTS. However, for parts of thermoplastic material providing SUPPLEMENTARY INSULATION or REINFORCED INSULATION, the test is carried out at a temperature of 25°C ± 2°C plus the maximum temperature rise determined during the tests of clause 19, if this is higher. The temperature rises of 19.4 are not taken into account provided that the test is terminated by the operation of a NON-SELF-RESETTING PROTECTIVE DEVICE and it is necessary to remove a cover or use a TOOL to reset it. John Allen | President | Product Safety Consulting, Inc. Your Outsourced Compliance Department® http://www.productsafetyinc.com 630-238-0188 Visit us at the D2P Show in Marlborough, MA. Booth 537 Sept 28th & 29th ________________________________ From: Covell, Richard <[email protected]> Sent: Wednesday, August 24, 2016 3:01 PM To: [email protected] Subject: Re: [PSES] Ball pressure test of thermoplastic parts Kris- The answers that others have provided are generally on point. The methodology for performing this test emanates from 60695-10-2. The IECEE, CTL has issued a decision sheet (DSH 391C) after feedback on proficiency testing some years back. You might find it an interesting read. http://decisions.iecee.org/iecee/SearchCMC.nsf/de_h.xsp?v=ctl Due to the layout of the site you’ll have to enter in the decision sheet # in the Ref. Number area. Best Regards Rick Covell From: Carpentier Kristiaan [mailto:[email protected]] Sent: Wednesday, August 24, 2016 8:58 AM To: [email protected] Subject: [PSES] Ball pressure test of thermoplastic parts Hi group, Does any-one know the reason/background of the ball pressure test of thermoplastic parts (IEC60950-1, clause 4.5.5) and the chosen temperature of 125C. This test is performed - for example – on the plastic parts of a direct plug-in power supply as these parts “carry” the mains power supply pins. I can’t imagine a situation there that requires such a test and certainly not at 125C. Thanks for your feedback! Best regards Kris Carpentier - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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To post a message to the list, send your e-mail to <[email protected]> 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 <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
