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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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Fundamentals of Product Safety DesignBerri RemenickNARTE Certified Product Safety EngineerProduct Safety ManagerWashington Laboratories, Ltd.September 14, 2007Gaithersburg, MD

http://www.wll.com


Outline
Outline

  • Background

  • Insulation

  • Component Selection

  • Labeling

  • Documentation

  • Wiring

  • Resistance to Fire

http://www.wll.com


Product safety requirements
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


Product safety hazards
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

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Product safety design guidelines
Product Safety Design Guidelines

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Design requirements
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.

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What is insulation
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)

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Insulation types
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)

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Reinforced insulation example
Reinforced Insulation Example

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Spacings creepage clearance
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)

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Creepage clearance
Creepage / Clearance

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Creepage clearance1
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

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Component selection
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


Component selection1
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


Labeling and marking
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.

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User instructions
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.

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Wiring and connection to the supply protective earth
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.

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Pe stud example
PE Stud Example

EMI FILTER

CHASSIS

TO OTHER

CONNECTION

GROUNDS

MECHANICALLY SECURED

GROUND: GREEN/YELLOW WIRE

SAME GAUGE AS OR BIGGER THAN SUPPLY

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Wiring and connection to the supply primary wiring
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.

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Resistance to fire and control of fire spreading
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

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Resistance to fire and control of spread of fire
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)

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Methods for meeting fire requirements in 61010 1
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

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Requirements for fire enclosure
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

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Parts not requiring fire enclosure
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.

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Plastic materials used for fire enclosure
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

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Plastic materials used inside a fire enclosure
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….

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Plastic materials used outside a fire enclosure
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….

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Washington laboratories ltd
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


Washington laboratories ltd1
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: [email protected]

http://www.wll.com