Transformer sales up as new medical EMC standard kicks in

REO (UK) has reported a sales surge in its range of REO-MED medical isolation transformers, which it puts down to the medical industry’s preparation for the new EMC standard that comes into play in November 2004. The introduction of this tighter standard for medical equipment has been driven by the proliferation of wireless devices by legitimate users in hospitals.

After November 1st, all medical equipment to which the current standard EN 60601-1-2 relates must comply with the new version of this standard, if it is to be marketed legally within the EU. This requirement applies to equipment already on the market. Compliance with only the old version of the standard will not be acceptable.

“Achieving satisfactory EMC performance has never been a matter for the equipment supplier alone,” explained John Symonds, director of REO (UK). “Even the best of equipment can malfunction if the end-user exposes it to unusual conditions. The new version of EN 60601-1-2 recognizes this shared responsibility for electromagnetic compatibility. Now, manufacturers need to do more than just show that their equipment meets the requirements laid down by the standard. They must also provide users with information that will allow the EMC performance of the equipment to be maintained under real-world operating conditions.”

The REO-MED range presents one potential aid to achieving EMC compliance and hence meeting the standard. These transformers minimize capacitive coupling between the primary and secondary windings, and also incorporate an earthed inter-winding screen, providing a useful degree of attenuation for electromagnetic interference over a broad range of frequencies.

The transformers provide an ungrounded power supply system that improves the reliability of the supply in ‘single fault conditions’ and reduces the leakage current. This effectively eliminates the potential for high touch voltages on the connected equipment. “This is essential in medical applications, where even the smallest shock may prove fatal to an already weakened patient” stated Symonds. Consolidation of the earthing system at one point also reduces ground loops, minimising earth leakage and making small signal measurement and transmission easier.

REO has also produced a series of practical guides which provide a detailed explanation of virtually every aspect of EMC compliance. Printed versions of these guides are available free of charge from the company, or they can be downloaded as pdf documents from the REO website.

The company is also able to supplement the information in the guides with specific advice relating to particular projects or applications.


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