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Lightning and surge protection of solar water heaters

1/3/2012

As a clean and economy energy, solar energy has been widely used by humans. With the acceptance of urban environmental energy and application, solar water heaters are gradually entering the public house. As the public lack of knowledge of lightning protection, in order to reduce costs or installation companies, in this way the lives of the people buried in future security risks.
 
Lightning protection of solar water heaters buried risk
 
The majority of the solar water heaters are installed in the highest point of the building, its height above the roof of lightning surge protection devices, and the remaining parts without grounding. Power lines, lightning radio control lines without invasive measures. Once being struck by lightning, a strong lightning current will be along the water pipes, hot water, the power cord into the bathroom, causing room electrical damage, while in the occurrence may result in personal injury.
 
The composition of solar water heaters
 
There are collectors of solar water heaters, water tank insulation, brackets, connecting piping, control systems and power system components. Here we showed our views from solar water heater’s direct lightning protection, power lines protection, and control lines protection.
 
Solar water heaters direct lightning surge protection
 
Solar water heater tank and collector generally set the highest point in the building, lightning protection should be set lightning rod for protection, the water heater should be within the protection scope of lightning rod. At the same time the water heater metal parts should be equipotential bonding with roof surge protection device.
 
Power lines lightning and surge invasion
 
The said power line is from the building power distribution system, usually directly from the power outlet, the other end directly to the water heater, lightning area LPZ0 is another way of lightning invasion, so it should be installed in the line surge protection device. With the characteristics of water heater supply simple and direct, it should be at least at its outlet installed surge socket. (The nominal discharge current no less than 8 / 20 μs 5kA – FV05D-SPC)
 
Control lines lightning and surge invasion
 
The said control line is another route of lightning invasion, so the line should be installed over-voltage protection device (AC and DC surge protectors, SPD). The sensing line in the water tank, its upper line is in LPZ0 area, the local electromagnetic field strength does not decay, and the line has been extended to the user's bathroom, in general, it should be set coarse protection and fine protection. The sensing circuit has a water line and water line composition. Therefore, install a Class I lightning arrester (power surge arresters SPD) in the water tank of the sensing circuit, where select 10/350μs waveform, impulse current no less than 5kA (Iimp> = 5kA), install in connection with the Monitor Class II surge arrester, where select 8/20μs waveform, max. discharge current no less than 40kA (Imax >= 40kA).
 
Various line shielding
 
For solar water heater, there are two metal lines through the roof to the indoor bathroom, through LPZ0 area to LPZ1 area, in the LPZ0 area, electromagnetic field strength does not decay. Therefore, set shielding in the heater power circuit, and grounding at both ends of the shield well.
 
Equipotential bonding
 
Equipotential bongding is an important part of solar water heater lightning protection, including outdoor and indoor metal structures equipotential bonding. Outdoor section includes metal stents, metal components, lightning rod, lightning protection zone, outdoor shield line grounding and over-voltage protection devices. Indoor section includes indoor circuit shield grounding, including surge protection device, indoor grounding and variety of ground equipotential bonding.
 
Summary
 
In summary, the solar water heater lightning surge protection can not be ignored. It should adopt an integrated and effective protection measures and devices have to do equipotential bonding with the building's lightning protection device, and then it can effectively reduce and prevent the occurrence of lightning, to avoid personal injury and property damage.