Safety testing of heating in electrical appliances
The proper safety testing of household appliances and other electrical items is an important and necessary step in protecting potential users. This can be assured through EU directives which refer to particular standards. The aim of the LVD project has been to support measurement and testing (M&T) laboratories in Newly Associated States, enabling them to fully implement the directive. One important international standard considered was ISO/IEC 17025, which includes criteria for M&T laboratories which produce testing and calibration results. The standard is similar to the ISO 9000 quality management system, but explicitly requires evaluation of measurement uncertainty and traceability. One of the tests that must be complied with was the heating of appliances. The appliance should not affect its surroundings more than specified. If it does overheat the possibility exists for damage to occur or even a fire to break out. Therefore, a proper understanding is needed regarding the heating of the appliance; this is achieved using a system of measurement known as the black test corner. Each measurement system contains an element of uncertainty. It was important to correctly evaluate the level of uncertainty. The LVD team studied how to guarantee correct traceability measurements of heating in the black test corner when a case study test was performed. The team developed a systematic approach to testing in the black test corner. Traditionally laboratories have employed different methods of testing, but these are only applicable to particular tested appliances. The black test corner could be considered as a complete measurement system. It can be recalibrated on a regular basis, providing traceable and reproducible measurements. A major benefit of the black test corner was that low voltage appliances, which are not required to be electronically tested, are none the less capable of starting a fire.
