FAQ - Lightning and surge protection for cell sites
|Answers to the most important questions concerning cell sites|
|Q: The HVI Conductor is installed on the C-rail directly next to the power supply line. Is this allowed?|
A: The HVI Conductor may only (!) be fixed using the specified material. If this is the case, the conductor may be installed directly next to the power supply line. However, please note that an electromagnetic field occurs which induces currents in the power supply line and may cause a high voltage drop. Therefore, surge protective devices must be installed at the beginning and at the end of the power supply line (e.g. DEHN DSE M2P 60 FM ( at -48V) and DEHN DVA CSP 3P 100 FM at supply voltage).
|Q: The antenna on the existing building is earthed according to DIN VDE 0855-300. Now new technology is to be retrofitted. Do I have to install an isolated lightning protection system?|
A: If the new technology is located in the protected volume and no (partial) lightning currents are injected into the building after retrofitting: No, the system is protected – if it is in good order and condition.
|Q: The lightning protection system on the roof was installed in 1999 and is still functioning and in good condition. Do I have to upgrade it because the antenna was replaced?|
A: No. According to the German “ABB bulletin No. 16”, existing equipment is still protected if the antenna is replaced.
|Q: An additional antenna is installed at the mast in the protected volume of the existing system. Does this eliminate the protection of existing equipment?|
A: No. Protection of existing equipment is still ensured.
|Q: The new supply line has to be routed through the building (chimney). What is to be observed with regard to the implementation and separation distance?|
A: The separation distance must be kept (flashover must be prevented) across the full length of the line that is routed through the building. Since this is normally not possible, check whether the line can be installed outside the building. Otherwise an isolated lightning protection system must be installed.
|Q: The antenna support structure was lengthened by 1m during retrofitting, the HVI Conductor is now too short, may I connect the conductor again or may I extend it?|
A: NO! None of the currently available types of the HVI series may be lengthened. A new conductor must be installed, if required. You may check whether it is possible to “relocate” the entire sealing end range by means of a 8 mm round aluminium conductor to compensate the missing metre.
|Q: Can I do without surge protective devices when using a HVI Conductor?|
A: No. When properly used, the HVI Conductor only ensures that the high voltage in the conductor is insulated and no flashover occurs. The physical law that every current carrying conductor creates a magnetic field around it and thus induces a voltage in the surroundings also applies in this case. Therefore, conductor systems in close proximity must be protected against surges.