Assessing and minimizing risks is managed in an ever more transparent way today, and it is now often a matter for the boss. Lightning and surge protection for structural installations also plays a part. At the end of the calculation, tolerable risk and the effort required are weighed up and assessed in relation to one another. That is the theoretical approach — but what does effective surge protection look like in practice?
Lightning discharges in storms are a frequent cause of transient surge voltages. Even remote lightning strikes can have an effect on electrical and electronic components. For one thing, in the vicinity of a strike there is always a rise in potential in the ground due to the earth resistance and the lightning current. This increase in voltage continues via the grounding system and the equipotential bonding conductors — and can particularly damage the insulation of devices and cables.
But also the electromagnetic field created during the short duration of the pulse can couple into signal lines inductively or capacitively. As a result, signals can be affected and devices with sensitive electronics are often destroyed by the dozen. Components to which copper cables are laid over long distances, outside of buildings in open spaces are particularly at risk. But even inside buildings there is a risk to signal lines — particularly if the electromagnetic tolerance is not specified when the lines are laid.
Switching processes of inductive or capacitive loads can strongly couple into signal lines laid in parallel and also lead to destructive effects — electronic components can fail here too. Initially, the cause is often unknown. In all these cases, surge protection for MCR applications increases reliability and system availability and has long been considered part of an innovative system.
Surge Protection Can Do More
Today, surge protection for MCR technology can do more than just protect against transient surge voltages. The components are often used as fully fledged terminal blocks in cable distribution cabinets — and offer a surprising amount of additional functions, which simplify starting up signal circuits as well as maintenance work at a later date. The development of the new Termitrab complete product range was also inspired by current market trends.
A space-saving, compact design is one of the strongest trends in process technology. In large process technology systems, several thousand signals and a correspondingly large amount of field cables often terminate in high-density marshaling cabinets. Termitrab complete now makes it possible to connect two signal conductors on an overall width of just 3.5 mm, thanks to its extremely narrow versions. As a result, on one meter of installation width, 572 signal conductors can protect against surge voltages.
The power dissipation which results from the decoupling resistors in the protective circuits has also been significantly reduced — this function is also targeted at high density requirements. Thanks to innovative protective circuits, all three categories — C1, C2, D1 — of the surge protection standard EN 61643-21 are also fulfilled on an overall width of just 3.5 mm.
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