interference

Keith Armstrong, worldwide electromagnetic compatibility specialist at EMC Standards, looks at problems with electrical interference and how construction managers can minimise their risk

Cranes are synonymous with the idea of development. Typically used to construct buildings, cranes aid the economic and social development of a town or city. However, cranes suffer from a persistent problem that is indicative of a significant threat to the future of technology: interference.

In the early days of the UK Department of Trade and Industry’s EMC Awareness Campaign, there was an infamous incident where a man was crushed to death by a crane. In this case, electrical interference caused the crane to prematurely release its load while the man was operating it with his radio-control pendant. Unfortunately, this tragedy is not an isolated incident.

There was another incident with a company that claimed to have made the controls and drives for the first large scale hovercraft-testing tank in the late 1960s. It was, in effect, a sophisticated travelling overhead crane, which ran the length of a gantry along overhead rails and towed a hovercraft shape along a large pool of water in an even larger building. In those days, they used resistor-transistor logic, which ran on a 40 V rail to provide noise immunity.