ELECTRICAL EQUIPMENT
them. This is enshrined in safety requirements such as the Electrical Equipment Regulations in the UK, the Low Voltage Directive and product safety standards. These assert that comprehensive testing must be completed on electrical products that are either manufactured or returned for repair. Moreover, properly maintained records of the product design for each manufactured item must also be kept. Generic product safety standards and European Directives make clear a requirement to ensure conformance from both. However, the common reaction still remains ‘Does this mean I have to do 100 per cent testing?’ Batch sampling and product verification tests are essentially designed to determine that type test and build instructions are being maintained via a set of ‘working standards’ and rely on a traceable scientific relationship between the sample and the rest of the batch. In order to maintain a proper relationship back to the ‘type approved product’, testing of the batch sample should theoretically involve a repeat of the type test. This could involve the use of external test house or the transfer of the sample to a dedicated, in-house test laboratory - with both cases likely involving high costs and complex test routines. In addition, where batch sampling results in a test failure or a safety problem, remedial measures must be put in place. This could involve shutdowns to production and product recalls until the extent of the fault is identified.
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PRO-ACTIVE In reality, this is likely to involve re-call costs (time, labour, discarded packaging etc), testing costs (which will now include skilled labour), rework costs (time, labour, parts if any), lost production (highly unlikely that all items are salvageable) and potential late delivery penalties. Similarly, it is clearly in the interests of manufacturers of finished products that the safety critical components used to assemble a product are satisfactory – preferably before being incorporated into the product. Many manufacturers now request ‘Certificates of Conformity’ from suppliers of safety critical components. There has been growing recognition of the advantages that can result in the pro-active identification of problems and defects before assembly. In this situation many electrical and electronics manufacturers now request ‘Certificates of Conformity’ from suppliers of safety critical components.
By complementing this approach with 100 per cent product testing, significant information can be gathered and used to improve and refine manufacturing processing and
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he importance of electrical safety testing is paramount to ensure that electrical and electronic products rolling off production lines are safe and that consumers will not be harmed when they use
SAFETY FIRST FOR ELECTRICAL PRODUCT MANUFACTURING
The need to ensure that manufactured electrical and electronic goods comply with required conformance standards is inextricably linked to effective product and component testing, says Nathan Barwell, category manager at Seaward.
techniques. Identifiable reasons for product failures can be highlighted and quickly acted upon. Even simple fault counters can indicate particular areas of the build phase that may require further investigation. In developing production line safety testing policies, product manufacturers will review their own processes for Class I and Class II products and accordingly introduce the three
main tests for ensuring product safety: High current Earth Bond measurement, Insulation Resistance measurement and High Voltage Flash (or hipot or dielectric strength) Test. In addition, many manufacturers will be driven by specific product standards and customer requirements, or even their own in-house guidelines, to complete functional tests (also known as run or load leakage testing).
Autumn 2022 UKManufacturing
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