Andy Pye speaks to an EMC specialist at EMC Standards about the problems with electrical interference and how construction managers can minimise their risk.
In the early days of the Department of Trade and Industry’s (DTI) 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, according to Keith Armstrong, worldwide EMC specialist at EMC Standards, 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 40V rail to provide noise immunity.
During commissioning, the machine suddenly started up by itself and proceeded towards the far end of the pool, having been set off by what was documented as a mains transient current. All the personnel on the site were standing by the access ladder to its gantry, but the only emergency stop button was on the gantry itself and they could not get to it.
Since it was not operating according to its programming, the crane ignored its limit switches and crashed through the end wall of the building. Luckily, nobody was hurt and the next version had emergency stops all around the building. While this does go some way in protecting against a similar incident, it is debatable whether this measure goes far enough.
According to Armstrong, if we are to ensure the safe adoption of new technologies and the stable use of equipment in general, it is vital that we prioritise the design engineering of equipment in compliance with the Electromagnetic Compatibility (EMC) Directives. These standards are in place to ensure that devices and equipment operate reliably with minimal risk of interference-induced hazards. An uncertainty is how in a post-Brexit world, UK construction industry will align itself with international norms, as it surely must, even though it will be at risk of having less of a voice on the standards committees.
Addressing EMC problems in the construction sector will become increasingly important in the coming years, so ensuring cranes and other equipment are fully protected to EMC Directives is a significant step in the right direction. With the right knowledge and training, project managers can build a safer future while staying on the right side of EU law.
“Traditionally, many electrical engineers and construction managers have been deterred by the perception that EMC is a complex topic,” says Armstrong. “While there are guides to EMC that demystify it without complicated mathematics, there is still a stigma surrounding it. In order to overcome this stigma and improve site safety, it is important that responsible people working on construction projects receive the right EMC training from power quality consultants.”
A source of help for engineers with EMC challenges
Power quality specialist EMC Standards is a new company that has been set up in Staffordshire to educate design engineers, electrical engineers, plant managers and other electrical practitioners about electromagnetic compatibility (EMC) issues. Set up by expert electrical engineers, the company aims to refresh the way people learn about EMC issues, moving away from the old ‘bricks and mortar’ methods to a new service that reaches a wider audience.
EMC Standards will share this information through its website, which contains vast amounts of downloadable information. There are a wide range of practical guides to regulations such as the 2004/108/EC regulations, which are the basis of EMC law in the UK.
“EMC problems usually occur when equipment is not installed according to the manufacturer’s guidelines or when it does not conform to EMC regulations,” explained Keith Armstrong. “This leads to electromagnetic and radiofrequency interference (EMI/RFI) that can raise energy costs and affect telecoms equipment as well as interfere with other equipment on the network.”