Transcript Document

Fundamentals
of
Product Safety
Design
Berri Remenick
NARTE Certified Product Safety Engineer
Product Safety Manager
Washington Laboratories, Ltd.
September 14, 2007
Gaithersburg, MD
Washington Laboratories (301) 417-0220 web: www.wll.com
7560 Lindbergh Dr. Gaithersburg, MD 20879
Outline
 Background
 Insulation
 Component
Selection
 Labeling
 Documentation
 Wiring
 Resistance
to Fire
Product Safety Requirements
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US/Canada:
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NRTL Listing (cULus, cTUVus, cCSAus)
Legal requirement, customer requirement, or to limit liability
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Europe:
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CE Mark
Legal requirement
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Others:
CB Report
To facilitate International Approvals.
Product Safety Hazards
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Electric Shock Hazards: Accessible parts over 30Vrms,
42.4Pk, or 60VDC.
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Energy Hazards: Energy level over 240VA or 8A
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Fire Hazards: Materials, Enclosure, Abnormal conditions
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Mechanical Hazards: Moving parts, Sharp edges,
Tipping, Handles
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Radiation Hazards: Lasers, UV, Sonic
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Thermal Hazards: External temps, component temps
Product Safety
Design Guidelines
Design Requirements
Protection against electric shock and
energy hazards:
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The OPERATOR can not touch bare or inadequately
insulated parts at hazardous voltage or energy levels.
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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.
What is Insulation?
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Physical barrier between two parts
(tape, plastic shield, wire insulation,
enclosure, etc)
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Separation between two parts through
air or along a surface (creepage or
clearance distance)
Insulation Types
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Functional / Operational Insulation (DC
input to ground)
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Basic Insulation (Primary to Ground,
TNV to Ground, TNV to SELV)
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Reinforced Insulation (Primary to
Secondary)
Reinforced Insulation Example
Spacings (Creepage / Clearance)
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Based on the required insulation for your circuit.
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Based on the maximum working voltage for your
circuit.
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Based on the environment the product will be used in
(Pollution Degree)
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Based on the PCB material: Material Group Comparitive Tracking Index (CTI)
Creepage / Clearance
Creepage / Clearance
Creepage
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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
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Clearance = distance between two points through the air
Clearance is measured on a populated sample
Component Selection
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Safety Critical Components must have the
appropriate approvals or additional evaluation
will be required.
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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.
Component Selection
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For NRTL approvals, all components must be UL approved.
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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)
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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.
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Approval certificates required (TUV or VDE Cert, CE
Declaration of Conformity, UL File number, etc.)
Labeling and Marking
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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.
User Instructions
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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.
Wiring and connection to the supply
– Protective Earth 
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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.
PE Stud Example
EMI FILTER
CHASSIS
CONNECTION
MECHANICALLY SECURED
GROUND: GREEN/YELLOW WIRE
SAME GAUGE AS OR BIGGER THAN SUPPLY
TO OTHER
GROUNDS
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.
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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.
Resistance to fire and control
of fire spreading
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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.
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Flammability ratings
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5VA – Most fire resistant
5VB
V0
V1
V2
HB40
HB75 - Least fire resistant
Foamed materials:
HF-1
HF-2
HBF
Resistance to fire and control of
spread of fire
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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)
Methods for Meeting Fire
Requirements in 61010-1
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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
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Components in primary circuit
- Components in secondary circuits that are not
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supplied by LPS
• - Components in secondary circuits supplied by LPS
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but not on V-1 material
• - Components with unenclosed arcing parts
• - Insulated wiring
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Parts not requiring Fire Enclosure
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- 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.
Plastic materials used for fire
enclosure
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Movable equipment <18kg:
V-1 or pass A.2
HWI test (if <13mm from high temp parts)
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Movable equipment >18kg or stationary equipment:
5VB or pass A.1
HWI test (if <13mm from high temp parts)
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Materials filling an opening in a fire enclosure:
V-1 or pass A.2
Plastic materials used inside a fire
enclosure
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Inside a fire enclosure:
V-2 or HF-2 or pass A.2
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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
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Material outside fire enclosure:
HB75 if <3mm or HB40 if >3mm or HBF or Glow Wire test at
550C
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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….
Washington Laboratories, Ltd.
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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
Washington Laboratories, Ltd.
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Give us a call or send us info about your product we’re here to help!
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Berri Remenick
Product Safety Manager
Phone:
301-473-1255
Fax:
301-473-1257
E-mail:
[email protected]
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