Alokin Lightning Shield
Protecting Equipment From Ground Potential Rise (GPR)

Under normal atmospheric conditions, the earth's surface exhibits a negative charge.  During a thunderstorm, the lower parts of the clouds become negatively charged and thereby push the negative charges on the earth's surface deeper into the ground enabling the positive charges to rise to the earth's surface.  Positive charges now rise up further on all conductive surfaces trying to recombine with the negative charges of the lower clouds. Since the negative charges of the lower clouds want to reach a charge equilibrium, they need to recombine with the positive charges on the ground.  This is done via stepped leaders, a pathway that is formed by the negative charges in the clouds towards the ground, allowing the negative charges to recombine with the positive upstreaming charges.  When this happens, most of the energy is released in an explosion of ultra high heat that is causing the shock waves we hear as thunder while a small amount of energy turns into visible light, showing the actual lightning strike. 

Primary and secondary lightning strike related issues can have severe consequence:  Death or injury to personnel and massive damage to equipment.

The most immediate and primary damage to electronic equipment is evident:  The equipment stopped working, often shows traces of fire damage caused by heat and is discoloured whereas secondary lightning induced damage to the internal components of electronic circuitry is often not visible right away. Silicon chips, capacitors, regulators, transistors and other discreet component may have experienced some heating only or have been subject to abnormally high voltage levels that could dramatically reduce the life cycle of the components without causing immediate failure.  In most cases, lightning induced damage to electronic equipment is caused by Ground Potential Rise (GPR) that is related to the general grounding of the communication site.

Modern electronic equipment often works on low voltage levels using little power and are therefore more susceptible to voltage fluctuations.  Even when surge protection devices (SPD) are used, their clamping voltage and switching time do not isolate the equipment instantaneously from the grid.  For a finite period of time the electronic equipment is vulnerable to voltage spikes and current flow because of GPR, long enough to either take out the equipment immediately or at a minimum, drastically reduce its life cycle:  Both are costly.

Good site grounding means that every grounding element has to do its designed job well:  Having the communication tower grounded to multiple ground rods does little if the ground cannot absorb and dissipate the lightning induced charges quickly.  The AC neutral that is grounded some distance away from the communication tower could see different ground resistivity and thereby absorb and dissipate the lightning induced charges at a different rate.  All it takes is a split second for an unequal/unbalance ground potential to exist between two separate paths and electronic equipment can be seriously damaged.

Traditionally and many decades ago when much less of the grounding science was understood, the safest and best way to protect against lightning induced damage was very simple:  Unplug the TV, radio or anything else connected to the grid and this holds true even today...
Climate Change Impact on Lightning

New research determining the impact of climate change on the world's lightning and thunderstorm patterns has found that for every one degree Celsius of long-term warming there will be a near 10 percent increase in lightning activity.

The study was led by Professor Colin Price, who is the head of the Department of Geophysics, Atmospheric and Planetary Sciences at Tel Aviv University in Israel.

The researchers ran state-of-the-art computer climate models and studied real-life examples of climate change to reach their findings.

What does the Lightning Shield actually do?
It completely disconnects the electronic equipment from the grid.  It literally unplugs it.

Why is that important?
If the electronic equipment is not connected to the AC ground, it cannot be subject to GPR.  GPR is only an issue if there are two or more separate ground paths to the equipment.  Once a transceiver is disconnected from the AC, the only other ground path is through the shield of transmission lines.  If that potential rises subject to a lightning strike, then it is shunted through the system ground via the Master Ground Bar (MGB) back into the earth ground.

How does the Lightning Shield disconnect the equipment from the Grid?
The Control unit of the Lightning Shield is connected to the 120 VAC grid.  Inside the Control unit are powerful relays.  The output of the switching unit provides the 120 VAC  that connects the equipment.  Normally, the relays are closed and therefore, the equipment is directly connected to the grid.  A sensing unit mounted outside the communication shelter monitors the levels of static electricity.  When it senses an increase of positive charges, it sends an interrupt request via a fiber optic cable to the Control unit and the relays open up, physically disconnecting the equipment from the grid.

How does the equipment, now disconnected from the Grid, continues to operate?
It requires back-up via an uninterrupted power supply (UPS).  The UPS is connected to the output of the Control unit.  When lightning approaches and an event is triggered that opens up the relays in the Control unit, then the UPS senses the power failure and automatically provides the back-up power from its batteries to the equipment.  Once the charge equilibrium outside at the sensor unit is restored and the thunderstorm has moved on, another input from the sensor to the Control unit causes the relays to close and equipment and UPS are again connected to the grid.

What else does the Lightning Shield do?
  • It monitors the AC line voltage and if outside user defined values, it can isolate the equipment.
  • It has remote interface capabilities and events such as alarms, GPR levels, Line voltage, etc. are logged and can be remotely accessed.

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