Cell sites are becoming more susceptible to lightning damage as new 5G radio electronics are more complex. They are also more sensitive since the transistors built inside integrated circuits are becoming smaller. “Whether it is the effects of the magnetic fields that are creating lightning discharges, or the electrical impulses that are being superimposed onto the wiring in these devices, there is a greater danger than ever to electronics on the tower from lightning,” explained Tony Surtees, Vice President, Engineering at Raycap.
Other factors are creating a greater need for surge protection devices (SPD). Because 4G and 5G radios are being installed at the top of the towers, they are even more vulnerable to the surges caused by lightning strikes, and those strikes are happening more frequently, according to Apostolis Sotiriou, Vice President, Sales at Raycap. “Tall tower constructions attract lightning,” he said. “Additionally, there are more and more thunderstorms bringing intense weather conditions to different areas of the U.S.”
In response to this constant threat, Raycap developed a proprietary technology, known as Strikesorb®, which is the building block for Raycap’s surge protection products, according to Surtees. The initial approach is to capture lightning at the lightning rod and safely route that energy to the ground using the down conductor system. The energy is then dissipated into a low-impedance grounding system. The power lines running across the tower site, can carry induced surges that in turn are directed into the installed equipment at tower top and bottom.
A typical lightning flash is about 300 million volts, which needs to be routed away from radios that operate on 48 volts. The parallel cables that are feeding up the tower to the radio heads also have a large amount of voltage induced onto them in the event of a lightning strike. Therefore, the next step is to divert that voltage away from the equipment using a surge protection device, which includes the Strikesorb technology.
Strikesorb is integrated into solutions managing power and fiber distribution to protect electronics at the tower top and bottom. When lightning strikes a tower or nearby, Strikesorb gives a path for it to go to the ground, instead of entering and destroying the radio. In addition to macro sites, small cell nodes also require electrical protection. Specialized connectivity and AC disconnect products have been developed for this application, complete with Strikesorb protection. If external surge protection is not installed, the sensitive communications equipment is not protected from lightning surge damage, and the site is at risk of equipment failure requiring costly field service.
The Differentiator
The overwhelming majority of the SPD manufacturers use a technology that was developed 30 or more years ago to protect today’s sophisticated electronic equipment. Their approach to surge suppression relies on using a multitude of bulk produced, commercial quality, low-surge current rated metal oxide varistors (MOV) or silicon avalanche diodes originally developed for electronic printed circuit board applications.
Strikesorb’s unique design features a distribution-grade MOV that can handle much larger surges without affecting performance. The company has made significant R & D investments to develop and validate Strikesorb to meet global safety standards.
“What makes Strikesorb unique is that it is designed to first handle and divert the very high energy in the environment of tall radio towers, so it has to be robust Simultaneously, it must reduce the energy to a very low level to protect the sensitive equipment that is on the other end of these cables.”
Strikesorb has been engineered and tested for use in AC and DC power applications, and the Strikesorb 25, 30, 40 and 80 modules are compliant to IEC 61643-11 and the UL 1449 5th Edition standards. The Strikesorb 35 surge protective device is designed specifically for DC applications operating at up to 1,500 volts and is compliant with the UL 1449 5th Edition, IEC 61643-31 and EN 61643-31 standards.
Making Strikesorb
Raycap has 100 percent control of the design, manufacturing, and testing process of Strikesorb, and it has improved the quality of the MOV so that it can handle higher surges. Over the years, Raycap has made incremental improvements to the technology, including migrating the size of the Strikesorb down to smaller and smaller packages to the current size of 25 millimeters wide and 10 millimeters thick.
“Being vertically integrated in our development gives us a lot of flexibility, so we can change our compositions, change the size of the unit, and customize it to fit different opportunities,” Surtees said. “The reason we were looking to get smaller is because it is to the customers’ advantage.”
Conclusion
Cell sites are the mission-critical components in communications networks, so providing sufficient protection to them for lightning and surge protection is a critical piece of maintaining a wireless network. This protection has been something that Raycap specializes in. Its technology, Strikesorb, results in the lowest possible let-through voltage and ensures optimum protection levels of critical infrastructure equipment, especially cell towers.
For more information find us at https://www.raycap.com/ or to schedule a presentation email [email protected].
By J. Sharpe Smith, Inside Towers Technology Editor
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