Interference immunity of specialist industrial plant

By the term `specialist industrial plant´ the author means the sort of plant in which reliability is all important. Large electricity generating stations are of this sort, but it was only in nuclear generating stations that the problem of EMC was seriously considered before the advent of the European Directive. At AEE Winfrith, part of the UKAEA, fundamental work on the problem of sensitivity to electromagnetic disturbance in reactor control instruments, started in 1962. A test procedure was developed in which disturbing RF currents were coupled to instrument cables by running an `injection´ line along the route of the instrument cables. Mains switching had been identified as the most serious source of transient interference and mutual inductance between passive lines as the way it coupled to neutron flux instruments. The whole concept, which involves suitable testing on all susceptible plant, is based on the premise that these sensitive electronic control instruments should work reliably for long periods in an industrial electromagnetic environment