Acceptance testing protocols: immunity of medical equipment to electrical mains borne interference

Reports of failures of medical equipment which may have been caused by electrical interference highlight the importance of providing equipment which can continue to operate in a noisy environment. The purpose of the present work was to develop an appropriate protocol to allow the tolerance of the medical equipment subject to mains borne interference to be ascertained. This was undertaken in two stages. A review of existing standards was carried out to compile a comprehensive menu of tests and then secondly data from mains disturbance analyses was studied to examine whether the tests were realistic and rigorous. It is important to realise that an acceptance test was being developed, rather than a type test. The equipment under test was introduced into, or returned to, patient care and was often of considerable value. It was essential not to cause any damage and, accordingly, certain tests such as the application of high energy pulses were avoided