EMC and functional safety

Electromagnetic disturbances can have serious consequences for functional safety, even where the European Electromagnetic Compatibility Directive (EMCD) has been fully complied with something not generally appreciated by design engineers and their managers. The EMCD is solely concerned with preventing technical barriers to trade in the EU single market and cannot properly deal with EMC-related functional safety issues. The EMCD only considers normal operational and typical EMC environments, whilst safety compliance must consider all reasonably foreseeable events and situations, including operational overload and environmental extremes, equipment faults, human error and misuse. The general misunderstanding as to the safety role of the EMCD, coupled with misgivings within industries where the safety implications of EMC have traditionally been widely recognised, prompted the IEE to establish a working group to produce some professional guidelines on how best to control EMC where functional safety issues are involved. EMC and safety experts from wide a range of industries: along with representatives of the Health and Safety Executive, were represented on the WG, which has published a guide to good practice. The Guide recommends addressing six questions relating to EMC and safety. Each question is discussed by the author.