List of common safety requirements for switching power supplies

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List of common safety requirements for switching power supplies [Copy link]

Safety standards applicable to power supplies

Contact current requirements

Location and requirements of safe distance

Comparison of safety distance requirements between standard rooms

General requirements for structural design safety regulations

Wire requirements: If the primary side wire is assembled and contacts the secondary components, double insulated wire or insulating sleeve is required;

Wire material requirements: The input wire soldering points on INLET generally require hook soldering to be reliable; the soldering points on the PCB need to be fixed with glue or have barbs;

Wire requirements: If one end of the wire becomes loose and causes contact between the primary and secondary components, the wire should be secured with a cable tie;

Spacing requirements: primary components and transformer core/PE ground (maintain basic insulation), primary components and secondary components (maintain reinforced insulation), secondary components and transformer core (maintain basic insulation);

Low-power switching power supply transformer: Generally, the secondary uses triple-insulated wires and the magnetic core is used as the primary side component. Reinforced insulation should be maintained between the magnetic core and the secondary components and the secondary pins of the transformer;

Linear transformer: Usually the secondary and the transformer core do not maintain basic insulation. In this case, the core is generally used as a secondary component, and the primary and the core maintain reinforced insulation.

Transformer skeleton (bobbin): Generally required thickness to be more than 0.4mm (IEC60950&60065), 1.0mm (IEC61558&60335-2-29)

Structural design safety standards requirements

Thermal stress relief test for plastic housing: Under normal conditions, the maximum housing temperature is +10°C, but not less than 70°C ---IEC60950/60065

Ball pressure test of plastic shell: Under normal conditions, the maximum shell temperature is +40℃, but not lower than 70℃ ---IEC61558

Ball pressure test of insulating materials supporting primary live parts: at least 125℃ ---IEC61558/60950

Fireproof enclosure requirements: V-1 or pass V-1 combustion test

---IEC60950

Glow wire test: 650 ℃

---IEC61558

Steel ball impact test (desktop product)

Drop test (portable/plug-in products)

Withstand voltage test (IEC60950/61558/60065/60601

Primary to secondary: 3000Vac/3750Vac/4242Vdc/4000Vac

Primary to accessible parts: 3000Vac/3750Vac/4242Vdc/4000Vac

Primary to PE ground: 1500Vac/1250Vac/2121Vdc/1500Vac

Primary to transformer core: 1500Vac/1250Vac/2121Vdc/1500Vac

Secondary to transformer core: 1500Vac/1250Vac/2121Vdc/1500Vac

Test time: 1 minute

Humidity test

Place the entire sample in a constant temperature and humidity chamber

Maintain for 48 hours, 28-30℃, 90-95% humidity (for general products)

Maintain 120 hours, 38-42 ℃, 90-95% humidity (for products used in tropical areas, such as Brazil, Saudi Arabia, Singapore, etc.)

After the storage time is completed, the withstand voltage test and insulation resistance test should be carried out immediately

Safety control requirements

Parts under safety regulations: input socket, fuse, PCB, X-cap, Y-cap, energy storage electrolytic capacitor specifications, switch tube, rectifier bridge, heat sink, fan, plastic shell, insulating sleeve, insulating tape, varistor, thermistor, transformer, inductor and other magnetic components;

When certifying parts under safety regulations, you need to provide the certification certificate of the corresponding region. If you do China CCC, you need to provide CQC or CCC certificate; if you do CE/TUV/GS, you need to provide VDE and other certificates with European certification; if you do UL, you need to provide UL certificate;

After a product obtains safety certification, the specifications and manufacturers of safety-controlled parts are not allowed to be changed without safety reporting.

CQC now also controls the materials used in transformers and inductors, and CCC certification also requires the provision of unimpregnated transformer sample evaluation structures.

The following materials are required for safety certification: BOM, PCB layout (silk screen layer and copper foil layer), transformer specification, inductor specification, fan specification, housing diagram, heat sink diagram, circuit schematic, insulation material diagram, label, product specification, certification application form, and samples (transformer samples without impregnation, blank PCB, test samples).

木犯001号

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MartinFowler

I learned a lot! Thanks!