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SCHURTER White Paper: Components and IEC 60335-1

SCHURTER White Paper: Components and IEC 60335-1
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SCHURTER White Paper: Components and IEC 60335-1 - 1

White Paper IEC 60335-1 household appliances Enhanced requirements on components The IEC 60335-1 standard in its 4th edition ensures even better fire protection in unattended electrical household appliances. To achieve this goal, the demands placed on glow wire resistance of the plastics used for insulating or mounting live components have been increased. Household appliances may catch fire due to power surges (glowing components), defective components, faulty electrical connections, arcing switching contacts, etcetera. Part 1, paragraph 30.2, "Test of heat and fire resistance" (see Figure 1), defines various requirements for insulating plastics. As specified in the revised 4th edition of IEC 60335-1 (which came into effect in May 2001), insulating materials used for live components in unattended appliances whose current exceeds 0.2 A must meet higher demands in glow wire testing. The plastic materials' after-flame times have been shortened accordingly. Requirements for components used in unattended appliances rated at >0.2 A The insulation materials used in close proximity (<3 mm distance) to the electrical conductor in appliances of this category must undergo two tests (see Figure 2). These are the GWFI (Glow Wire Flammability Index) and the GWIT (Glow Wire Ignition Temperature). Parts of Non-Metallic Materials in Household Equipment, IEC 60335-1, Chapter 30.2 Test of Heat and Fire Resistance Attended Appliances Chapter 30.2.2 The IEC 60335 standard on the "Safety of household and similar electrical appliances" comprises two parts. Part 1 (IEC 60335-1) is the basic standard governing the majority of the general requirements placed on all electrical household appliances, while Part 2 (IEC 60335-2-xx), see Table 1, is appliancespecific and governs special features such as whether an appliance is deemed unattended or attended, the definition of the test procedures, tests concerning the improper use as well as distance measures including pollution degree. IEC 60335-2-5 Washing machines Portable cooking appliances Misc. kitchen appliances Cooling appliances Professional cooking appli ances Heat pumps, air conditioners Circulation pump Unattended Appliances Chapter 30.2.3 Part must Part must meet GWT of meet GWT of 650 °C 750 °C Material must meet GWIT of >675 °C or Part must meet GWT of 650 °C See figure 2 Regulations have been stringent Figure 1: Overview of plastic components in electrical household appliances Table 1: Examples according to household appliances standard, Part 2 Part 2, paragraph 30.2, defines whether an appliance as defined is to be deemed attended or unattended and whether it uses the relevant components, such as fuse holders, appliance couplers, timers, circuit breakers for equipment, relays, motors and locks. Basically, the rule applies that appliances with a built-in timer or program controller or appliances operated by remote control are to be deemed unattended, while portable appliances are to be deemed attended. However, there may also be attended and unattended versions within a Part 2 standard, e.g. the grill with or without timer as specified in IEC 60335-2-6. The transition period, during which appliance manufacturers were still allowed to use components not covered by the standard, has expired in the meantime for all appliances approved in accordance with IEC 60335-1. Material meets GWFI of >850 ºC Part meets GWT of 750 ºC Flame <2s Material meets GWIT of >775 ºC Flame <5s Yes Surrounding Parts V-0 or V-1 Classification Surrounding Parts Needle Flame Test Part approved Figure 2: Overview of approval of components used in unattended appliances The aim of these tests: • The GWFI, using a glow wire, establishes the materials' self-extinguishment/afterflame behavior in the event of an open fire. This test corresponds to the after-flame test according to UL 94. During the GWFI test (see Figure 3) the material, while allowed to ignite at 850 °C, must self-extinguish within less than 30 seconds after the removal of the glow wire. The materials are tested in the form of plates of varying thickness according to IEC 60695-2-12. The material tested must meet this requirement otherwise no approval is possible.

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SCHURTER White Paper: Components and IEC 60335-1 - 2

White Paper • The GWIT establishes the materials' ignition behavior, also using a glow wire. Experience has shown that unattended appliances in particular tend to self-ignite when components fail, causing fires in the process. The intention behind this stricter regulation is to better protect end users against such fires. During the GWIT test, the material may not ignite at 775 °C, or the flame must self-extinguish within five seconds. No flaming drip is permitted. Provided that the material tested meets this requirement, components are granted approval without further testing. • As an...

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