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Fundamentals of Product Safety Design Berri Remenick NARTE Certified Product Safety Engineer Product Safety Manager Washington Laboratories, Ltd. September 14, 2007 Gaithersburg, MD. http://www.wll.com. Outline. Background Insulation Component Selection Labeling Documentation Wiring

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  1. Fundamentals of Product Safety DesignBerri RemenickNARTE Certified Product Safety EngineerProduct Safety ManagerWashington Laboratories, Ltd.September 14, 2007Gaithersburg, MD http://www.wll.com

  2. Outline • Background • Insulation • Component Selection • Labeling • Documentation • Wiring • Resistance to Fire http://www.wll.com

  3. Product Safety Requirements • US/Canada: NRTL Listing (cULus, cTUVus, cCSAus) • Legal requirement, customer requirement, or to limit liability • Europe: CE Mark • Legal requirement • Others: CB Report To facilitate International Approvals. http://www.wll.com

  4. Product Safety Hazards • Electric Shock Hazards: Accessible parts over 30Vrms, 42.4Pk, or 60VDC. • Energy Hazards: Energy level over 240VA or 8A • Fire Hazards: Materials, Enclosure, Abnormal conditions • Mechanical Hazards: Moving parts, Sharp edges, Tipping, Handles • Radiation Hazards: Lasers, UV, Sonic • Thermal Hazards: External temps, component temps http://www.wll.com

  5. Product Safety Design Guidelines http://www.wll.com

  6. Design Requirements Protection against electric shock and energy hazards: • The OPERATORcan not touch bare or inadequately insulated parts at hazardous voltage or energy levels. • Hazardous Voltage Level is typically >30Vrms, 42.4Vpeak, or 60VDC. Hazardous energy is typically >240VA or 8A Protection may be provided via insulation, guarding or interlocking. http://www.wll.com

  7. What is Insulation? • Physical barrier between two parts (tape, plastic shield, wire insulation, enclosure, etc) • Separation between two parts through air or along a surface (creepage or clearance distance) http://www.wll.com

  8. Insulation Types • Functional / Operational Insulation (DC input to ground) • Basic Insulation (Primary to Ground, TNV to Ground, TNV to SELV) • Reinforced Insulation (Primary to Secondary) http://www.wll.com

  9. Reinforced Insulation Example http://www.wll.com

  10. Spacings (Creepage / Clearance) • Based on the required insulation for your circuit. • Based on the maximum working voltage for your circuit. • Based on the environment the product will be used in (Pollution Degree) • Based on the PCB material: Material Group - Comparitive Tracking Index (CTI) http://www.wll.com

  11. Creepage / Clearance http://www.wll.com

  12. Creepage / Clearance Creepage • Creepage = distance between two points along the surface • Creepage is measured on 1:1 artwork or on a blank board • Locations of circuits determined by reviewing schematics Clearance • Clearance = distance between two points through the air • Clearance is measured on a populated sample http://www.wll.com

  13. Component Selection • Safety Critical Components must have the appropriate approvals or additional evaluation will be required. • Safety Critical Components: • Devices in the AC path (inlets, fuses, switches, power supplies, transformers, etc.) • Motors, fans • Power conversion components (AC-DC or DC-DC Converters) • Any isolation component (Transformer, Bridging Capacitors, MOVs,) • Wiring • Batteries • Others depending on their application. http://www.wll.com

  14. Component Selection • For NRTL approvals, all components must be UL approved. • For CE Mark approvals, all components must have a European approval such as CE, TUV, VDE, etc. (exception: fuses and wiring can be UL approved) • For GS or CB Scheme approvals, all components must have a TUV, VDE, or other official European approval. CE Mark is not acceptable for these approvals. • Approval certificates required (TUV or VDE Cert, CE Declaration of Conformity, UL File number, etc.) http://www.wll.com

  15. Labeling and Marking • Rated voltage, current or power, frequency • Manufacturer’s name or registered trademark. • Model or type number. • Fuse replacement info (if applicable). • IEC symbols wherever possible. • Warnings and Cautions appropriate for the particular equipment. http://www.wll.com

  16. User Instructions • Installation Instructions - information regarding mounting, connection to the supply, ventilation, input ratings, etc. • All information regarding use, cleaning, maintenance (if necessary). • All safety warnings and cautions. • Rack Mount instructions. • Safety-related information to be in appropriate language of the country you are exporting to. • Some standards have entire sections of specific info that must be in manual. http://www.wll.com

  17. Wiring and connection to the supply – Protective Earth - • PE conductor must be green/yellow or bare insulation conductor • PE connections must be double secured so that both the wire and insulation are crimped • IEC PE symbol shall be marked adjacent to PE stud • PE conductor shall connect to chassis directly from input (inlet, terminal block, etc). • PE conductor must be secured with washer and locknut. • Additional PE conductors can be secured to PE stud with a second washer and locknut. http://www.wll.com

  18. PE Stud Example EMI FILTER CHASSIS TO OTHER CONNECTION GROUNDS MECHANICALLY SECURED GROUND: GREEN/YELLOW WIRE SAME GAUGE AS OR BIGGER THAN SUPPLY http://www.wll.com

  19. Wiring and connection to the supply – Primary Wiring - • All AC wires shall be double secured. Double securement can be met by: Double crimp connector or Single crimp connector and cable tie or Single crimp connector and shrink sleeving. • AC wiring shall be rated for the maximum working voltage and current. • AC wiring shall be isolated from low voltage wiring or low voltage parts, this can be accomplished by: Shrink sleeving the AC conductors or By routing the AC conductors away from low voltage wires and securing with cable ties or By using UL1015 Reinforced Insulation wire. http://www.wll.com

  20. Resistance to fire and control of fire spreading • Enclosures, components, and other parts shall be constructed such that propagation of fire is limited. Flammability of enclosure, internal, and external parts shall be adequate for the use of that part. • Flammability ratings • 5VA – Most fire resistant • 5VB • V0 • V1 • V2 • HB40 • HB75 - Least fire resistant • Foamed materials: • HF-1 • HF-2 • HBF http://www.wll.com

  21. Resistance to fire and control of spread of fire • 60950-1 • Fire enclosure openings shall be: • Top and side openings shall be: • less than 5mm in any dimension or • less than 1mm in width regardless of length or • meet the 5 projection rule. • There shall be no bottom openings (some exceptions allowed but difficult to meet) http://www.wll.com

  22. Methods for Meeting Fire Requirements in 61010-1 • Requirement: There shall be no spread of fire outside the equipment in Normal or Single Fault Conditions. • Methods of Compliance: • A: Testing in single fault conditions • B: Reducing sources of ignition within the equipment • C: Containing fire within the equipment should it occur http://www.wll.com

  23. Requirements for fire enclosure • - Components in primary circuit • - Components in secondary circuits that are not • supplied by LPS • - Components in secondary circuits supplied by LPS • but not on V-1 material • - Components with unenclosed arcing parts • - Insulated wiring http://www.wll.com

  24. Parts not requiring Fire Enclosure • - Motors • - Transformers • - Wiring and cabling insulated with PVC, TFE, PTFE, • FEP, neoprene or polymide • - Connectors in secondary circuits powered by less • than 15VA or LPS • - Components in secondary circuits supplied by LPS • and on V-1 material • - Components in secondary circuits supply by max • 15VA and on HB785 if <3mm or HB40 if >3mm. http://www.wll.com

  25. Plastic materials used for fire enclosure • Movable equipment <18kg: V-1 or pass A.2 HWI test (if <13mm from high temp parts) • Movable equipment >18kg or stationary equipment: • 5VB or pass A.1 HWI test (if <13mm from high temp parts) • Materials filling an opening in a fire enclosure: V-1 or pass A.2 http://www.wll.com

  26. Plastic materials used inside a fire enclosure • Inside a fire enclosure: V-2 or HF-2 or pass A.2 • Exceptions: • Electronic components (IC’s, optos, etc.) mounted on V-1. • Wiring and connectors insulated with PVC, TFE, PTFE, FEP, neoprene, or polymide. • Clamps, cable ties. • Wire marked VW-1 or FT-1 or better. • Others…. http://www.wll.com

  27. Plastic materials used outside a fire enclosure • Material outside fire enclosure: • HB75 if <3mm or HB40 if >3mm or HBF or Glow Wire test at 550C • Connectors: • V-2 or pass A.2 or mounted on V-1 and be small or be in secondary circuit with max 15VA • Exceptions: • Electronic components (IC’s, optos, etc.) mounted on V-1. • Wiring and connectors insulated with PVC, TFE, PTFE, FEP, neoprene, or polymide. • Clamps, cable ties. • Others…. http://www.wll.com

  28. Washington Laboratories, Ltd. • Help you select the proper Directives and Standards to apply to your product. • Evaluate and test your product to the appropriate Safety Standard and offer solutions for non-compliances. • Provide product design assistance. • Obtain cTUVus, cCSAus, cULus, GS Mark, and other approvals. • WLL is a Partner Test Lab for TUV Rheinland for 60950-1, 61010-1, and 60065 http://www.wll.com

  29. Washington Laboratories, Ltd. • Give us a call or send us info about your product - we’re here to help! • Berri Remenick • Product Safety Manager • Phone: 301-473-1255 • Fax: 301-473-1257 • E-mail: berrir@wll.com http://www.wll.com

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