Giessen. The summer of 2011 has been rather cool and changeable so far, recently even bringing a few heavy downpours and minor thunderstorms to Central Hessen. Unfortunately, it is not as rare as you might think for such storms to lead to lightning strikes in houses or their immediate surroundings. Pulling the plug during thunderstorms is certainly an option, but it is often no longer a practical solution given the large number of devices available today. However, Frank Hoffmann, head of the MIT.N network company of Stadtwerke Gießen, knows that protective measures are definitely worthwhile. "The damage caused by lightning strikes in homes and businesses is sometimes enormous and is not necessarily protected by the external lightning protection of the house," he says.
Many houses are equipped with an external lightning conductor, which diverts the enormous amounts of energy from a direct strike into the ground. However, this alone is not enough to prevent voltage peaks in the building's power lines. The expert therefore recommends the additional installation of separate surge protection. This voltage protection in the basement not only shields the cables in the house itself, but also the expensive and sometimes very sensitive household and entertainment electronics. PC microprocessors and hard drives with many gigabytes of important documents and memories are particularly at risk.
There is also a solution for those who live in rented accommodation and are therefore unable to install separate voltage protection for their home themselves. "A relatively cheap and uncomplicated alternative is a simple power strip with surge protection from the DIY store," says Frank Hoffmann. This doesn't cost much and can still protect at least the most important devices.
Incidentally, photovoltaic systems on the roof also need protection - especially those mounted on metal stands. If the lightning protection is not correct, the electronic centrepiece of the system, the inverter, will be destroyed immediately in the event of an incident. If you have any doubts, you should consult a specialist at the earliest opportunity.
Correctly insured
In addition to technical precautions, good insurance cover is also important. After all, thunderstorm damage falls under "force majeure", so by definition it can never be completely ruled out. It is crucial that the insurance not only covers damage from a direct lightning strike in the house, but also all surge damage, regardless of where the lightning strikes. A look at the small print of the policy avoids nasty surprises in the event of a claim.
Secure power grid
However, not all measures to protect against thunderstorms and severe weather have to be borne by citizens alone. The utility industry, i.e. municipal utilities and grid operators, also make a contribution. If you think back to your childhood, you will realise that the lights used to flicker more often and you always had a few candles to hand in the summer. This is because power cuts were simply more frequent during extreme weather events than they are today. Currently, the statistical average nationwide is around 15 minutes, in Giessen and the surrounding area it is only around 11 minutes. By way of comparison: in Austria it gets dark for 37 minutes per year, in Italy for 88 minutes and in France for 159 minutes. The head of the grid in Giessen knows why: "Like many grid operators in this country, we have replaced lightning and storm-prone overhead lines with well-secured underground lines wherever possible in recent years," says Frank Hoffmann. "We now have a cabling rate of over 95 per cent in the Mittelhessen Netz GmbH (MIT.N) area." In total, Stadtwerke Gießen manages more than 2,800 kilometres of lines and over 700 smaller transformer stations via MIT.N.
The so-called ring circuit of the five Giessen substations with their eight high-performance transformers also contributes to reliability. Each one weighs around 60 tonnes and transforms the electricity of the nationwide extra-high voltage grid from 110,000 volts down to 20,000 volts. "If there is a problem, our employees in the control centre react immediately and rebalance the voltage and frequency in the grid," explains Frank Hoffmann. "This is only possible because we have considerable power reserves. We often only run our transformers at half power. That sounds unreasonable at first, but if we were to be stingy here, outages would occur much more frequently." This could be extremely expensive for industrial and commercial companies in and around Giessen, as power failures would not only cause the lights to flicker briefly, but could also ruin expensive workpieces and machines.
12.08.2011