RR338 - Measurement and analysis of megnetic fields from welding processses
Welding is ubiquitous in manufacturing and fabrication industries using relatively high currents that generate significant magnetic fields around cables, work pieces and electrodes. European Directive (EC/40/2004) on the restriction of exposures of workers to electromagnetic fields (EMFs) will be implemented in UK legislation by April 2008.
Basic field measurements are compared to reference levels at various frequencies, as recommended by the International Commission for Non-Ionizing Radiation Protection (ICNIRP). Worker exposures exceeding the reference levels are not necessarily harmful, but indicate the need for more detailed assessments to check compliance with basic restrictions. Measured fields are compared with the effective reference levels, taking account of the frequency components (harmonics) of the fields. Measurements were made for three resistance welding machines and five arc welding power sources. General conclusions were that the ICNIRP reference levels are exceeded at distances of less than 30 cm from the electrodes of resistance welding machines and at distances less than 20 cm from the cables of some arc welding equipment, depending on the welding current.
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