Surge Protection: Protecting Electrical Equipment from High Voltages
Every now and then it happens that a lightning goes straight into a house. If at this time electronic devices are connected directly to the power grid, they are literally "grilled". For this reason, there are various overvoltage protection measures that private persons can carry out in their household.
Thunderstorms in Germany start mainly in the warmer months between May and September . The strong sunlight warms the air, causing much water to evaporate. If cold air hits warm air, warm, humid air rises upwards. Water vapor condenses and swelling clouds form. These may grow into cumulus clouds, where there are strong upwinds and small raindrops fall out. The raindrops are carried further upwards where they freeze. The now heavy drops fall in the form of hailstones towards the earth.
The cloud now has a different charge: above positive, below negative. Within the cloud enormous tensions arise which discharge themselves as a lightning strike. This is done in two ways:
- As a voltage balance in the cloud or
- as a balance between the lower part of the cloud and the ground.
The main cause of serious overvoltages is lightning strikes in close to signal and power lines . The effects of lightning induce undue stress in conductor loops over a radius of approximately 200 meters. Even within a radius of two kilometers, dangerous potential differences can occur due to earth resistance.
- External Lightning Protection : Home builders should already plan for external lightning protection when building their own home. Later retrofitting is cumbersome and costly. The so-called lightning conductor is used to dissipate the lightning current to earth in an emergency, without any danger for the residents of the house. Homeowners can prevent fire damage with this surge protector. The installation of the protective measure is carried out exclusively by electricians , who are familiar with the components, materials, regulations and standards. The external lightning protection basically consists of three components:
- On the roof of the building the capture device is installed. It must tower above the height of the house, attached antennas and chimneys. It is important that the equipment can withstand the melting that occurs during a lightning strike and can absorb the current.
- After the lightning strike, the energy flows to the discharge system , which runs along the House walls vertically down leads. In this way, a Faraday cage is created which directs the lightning current towards the earth.
- The grounding is incorporated into the concrete foundation, which discharges lightning currents into the ground.
- Internal lightning protection : The external lightning protection alone is not sufficient, because expensive devices can be destroyed even by this protective measure by the so-called overvoltage damage . Only a surge protector inside the house can protect electrical appliances from lightning. This protective measure also consists of three components Type 1 arrester, Type 2 arrester and Type 3 arrester:
- Coarse protection : The Coarse protection is installed in the meter distributor and costs around 500
- Medium protection : Approximately 200 euros are due for the Type 2 arrester , which is installed, for example, in the electrical distributor.
- Fine protection : This is installed in buildings, in which sensitive components are used. Possible is the installation in sockets. Basically, almost all manufacturers of electrical and electronic devices have a Fine protection , but this is not of equal quality as an external protection.
- Protection for electrical installation : Schuko-outlets are part of the electrical installation. When installing the models, you should be careful to buy products with surge protection. It is important that the sockets are safe, reliable and of high quality. This proves, among other things, the VdS certificate.
- Subsequent backup : In the past, most people pulled the plug from TV and Co. during thunderstorms. Although this measure is effective, it is cumbersome and not always effective. Because who is not at home during a thunderstorm, has a problem. In addition, there are devices that can not be easily disconnected from the mains, freezers, for example. If you want to retrofit an overvoltage protection, you will find socket strips from companies like Brennstuhl or APC, but also intermediate plugs and combination intermediate plugs. Simple sockets only provide an on-off switch. In contrast, modern plug-in connectors have integrated overvoltage protection, which protects electrical devices even if the strip has not been switched off in good time. Practical side effect: The socket strips can be used to switch off stand-by devices completely and thus save energy.
- Protection for tenants : Tenants can install Type 3 arresters . These protect devices such as televisions, telephone systems, receivers and home electronics. Nevertheless, there is a risk that a mismatched surge protection will ultimately be ineffective. The landlord is ultimately responsible for staggered protection.
In devices, data line connections and mains power supplies (antenna cables, LAN, etc.) are protected against overvoltage . Some network devices (a splitter, for example) are cheap, so upgrading to over-voltage protection does not always make sense. With LAN and Ethernet, there is already some protection thanks to the transformer isolation , while fiber optic networks are not endangered.
Whether a system or a system is to be protected is decided on the basis of the following priorities:
- All plant components which are in principle endangered must be protected. Long data lines, outdoor antennas are particularly vulnerable.
- Systems that are valuable should also be protected. This category includes computers, hi-fi systems, etc.
- If there is a risk of injury in the event of possible overvoltages for people and / or buildings, appropriate measures must also be taken. This is rarely the case in the private sector, mentioning the loss of elevators or medical equipment.
Although lightning damage is included in the coverage, the scope of protection is limited to & sect; 2 No. 3 VGB 2010 (1914) (PDF, 78 KB). Thus, only the things are destroyed, which were destroyed by the passage of lightning. Short-circuit, overcurrent and overvoltage damage are only insured if the insured property has suffered other lightning damage.
Basically, there are several ways in which lightning can damage things: An object may be damaged by heat ignite. This damage is insured as a fire damage. However, as insured danger & quot; lightning strike & ldquo; It means damage caused mechanically, without causing a fire. Mechanical damage (& quot; cold lightning strike & quot;) arises from the rapid heating of water contained in each article. The water expands many times so that the objects burst.
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