Notes: Although the lightning strike is dc, due to the fast rise time to peak current, there is significant RF energy. Polyphaser's GXTM Series Bias-T products are RF path protectors with an integrated, protected DC Bias-T function. Protectors: Notice:Much of the lightning protection discussion pertains to RF grounding also. The overall physical installation of a bulkhead entrance panel is shown in the PolyPhaser online catalog. This leaves bare steel to rust and not provide an optimum connection to earth. Since most soils are stratified, the best way to determine the effectiveness of a ground system is to measure it. Just a word to those who tell us that they are safe from lightning because they always disconnect the coax from their equipment. This means that the anchor is now insulated from the surrounding Ufer ground! If they cannot spread out in a reasonable time frame, the back up pressure (voltage) will find or create another path. Based on its extensive experience with multi-stage surge protection, PolyPhaser continuously expands its product offering to support the needs of advanced network applications with technologies such as DC Block, DC Pass and Ultra Low PIM, Coaxial RF and Grounding Protection Innovation. Ground Measurement: eHam.net provides recognition and enjoyment to the people who use, contribute, and build the site. I have 5 Alphe Delta switches with no problems. stream Since concrete is conductive and forms a Ufer ground, and rebar is a very hard (heat treated) steel which will rust, the rust on the surface of the rebar, which is a non-conductive oxide when dry, will prevent further oxidation. We have only seen this happen once on a mountain top in the Nevada desert. (See the Noble Metal Table for a ranking of commonly used metals.). This could be the house phone lines and power lines. The phone connection at the street was blown apart and the lid blown 95 feet from the underground connection. This makes the currents smaller than a ground system using concentric rings or a ground grid. Any surge energy arriving on the coaxial cable, power and control wiring, or inadequate equipment ground system could find a lower inductance path to ground through your equipment and conductive concrete floor. The next thing to measure is distance. Every conductor has measurable inductance. The greater the distance between the protectors, the more serious the problem. Use a Since strike energy is a high frequency pulse, a low inductance path to ground becomes a critical factor. stream There are two ways of finding out if your ground system is in need of work. The ground system, if too small in area, will cause more energy to traverse the cables and other lines to the shack. Since all towers have some inductance, leaving the tower at a point above ground will allow some of the strike current to continue on the coax line (both the center conductor and shield) toward your equipment. I installed the best protection Polyphaser has, and have not had any problems (thank God) since. All Rights Reserved. Document Number PEN1030:An interconnected concrete tower base can help the tower ground system. In my caseit's Polyphaser. It is one of the most widely used metals for atmospheric exposure. Once a ground system is in the ground it will start to age. antenna cables, and polyphaser surge protectors for both radios. They are usually large low inductance conductors. So significant, that voltages in the order of several hundred thousands volts could be present during a strike. Longevity: Since the tower is a conductor and is well grounded, all of the coax lines should be grounded (using a grounding kit) at the top of the tower close to the antenna and at the base of the tower before they come toward your equipment. This added inductance of the coax line will buffer the energy entering your equipment area. 7$j.`hDJ(zZ@bvq9ZY u1Xfv9WF3{{= `$ gUZ}!<9jvYKD_}@50!SlfCUl^"X5`('3l @-IPRkwLTQKug[03k0/\ gWN<8f9("->Fp|NH!!Qe5_DEzQz.isYIZyFT4 d !cjQn,5LODW^1tK]O/A8G};)''#v@5@^y%H$=\Aw"[]AhE8p}!_ The protected lines should then be placed within EMT (metal) conduit that is grounded only at the tower-base end. The receiver requires a ring terminal with a 14-AWG copper wire to secure to the primary ground, as shown: NEBS (Network Equipment Building Systems). Handles 50 kA max. Since we are dealing with a fast rise time event, the inductance of the tower and paralleled coaxial cables become the primary factor in determining the amount of instantaneous peak voltage developed between the strike point and the bottom of the tower. Since there is a high frequency component, the inductance (effecting transient response) of the ground system is important. If one radial gives X resistance, then two will deliver an equivalent parallel rule plus 10%. The significance of being more noble means any other metal buried and connected to your copper ground system will be more anodetic and thus become sacrificial. Single point grounding should be easy to do if the equipment is mounted inside a metal enclosure. The resultant molten copper is deposited into the lower mold cavity where it burns away any oxides and creates a larger fused connection. Related Media 433721_433721_POL.pdf 433721_POL.pdf Technical Specs A protector on each of the l/Os will protect that path from damage. A rock layer will hold water and salts so the conductivity above should be good. PolyPhaser's patented products are designed to protect the most sensitive equipment for Amateur Radio, Military, Emergency Communications, GPS and many other RF and Microwave communication applications. A lightning ground system should be capable of dispersing large amounts of electrons from a strike over a wide area with minimum ground potential rise. Be careful when connecting a ground system to your electrical utility ground rod. The sharp corners of equipment cabinets can breakdown the air, causing current to flow. Once the surge is inside the building and on the equipment chassis, it is almost too late to try to protect the equipment. When these two parallel inductors to ground are combined (3.9uH and 2.7uH), the lower section of tower has an inductance of 1.6uH. This may not be a sufficiently low inductance path and it will radiate to other wires/equipment inside the house. If 8 foot [2.44 meters] rods are used, they should be placed on 16 foot [4.88 meters] centers. Protectors:Passive Intermodulation produces signals at unwanted frequencies that can interfere with RF signal reception. The large surface area strap is necessary to provide a low inductance path to ground for the surge energy as well as provide for the high frequency component of the strike energy. Also fundamental to a good protection scheme is the creation of asingle point groundwithin the ham shack. This is the accelerated corrosion (loss) of the least noble metal (anode) while protecting the more noble (cathode) metal. If none are available, regardless of the path distance, and it is impossible to run a strap down the side of the building, then the antenna just cant be grounded! Polyphaser at cable entry on dual bander, Polyphaser at feedpoint on wire. This is the only protector I will put into a naval installation, electric utility SCADA system or public safety system (911 police/fire). When lightning strikes, a tremendous rush of electrons move down the tower and out into the ground/radial system. I have specified, installed and maintained about 2000 Polyphaser proectors, from HF applications up to 6 GHz, power protection devices, data and telephony protectors. Infinite Electronics brand PolyPhaser has released a new line of fiber terminal boxes, splitter distribution boxes and rack-mount panels billed as ideal for use in communications, telecom, cable TV, surveillance and monitoring systems. There are several ways to accomplish this. And I've put a webpage up that's seen lots of visits on the proper way to ground a system. In my case it was more price driven buying in qty. The directly applied or induced voltages on the center conductor would roll off and arrive after the shield pulse, producing large differential voltages between shield and center conductor. Ten percent of all strikes will exceed 60,000 amps on the first pulse and one percent will exceed 120,000 amps. The grounding of the plate or panel is very important. The only time I have ever had a problem was when the protector was misapplied to the system (wrong power rating, wrong power rating, high reflected power, not-common grounding point, no weatherproofing). Consequently, it is better to have an extensive radial and ground rod system rather than a smaller ground system with doped soil. It is closest to ground and will have the lowest inductance connection to the grounding system. Grounding both the antenna and the single point ground connection in the equipment room is easy for buildings with structural steel frames just bond to the building steel. Any insulated signal lines are subject to damage as is the source power supply. If the area is not large enough, the earth connection will suffer. AC power line protectors and control/data line protectors are connected to the single point ground to complete your defensive strategy. Many tests have been done, dating back to 1968, that prove the Ufer is a safe and effective way of augmenting a ground system. <> 3) Ground Radials: Throwing the coax out the window is not a solution, especially if the coax has already entered the house from the antenna or the antenna is roof mounted without a ground path. Since concrete readily retains moisture for long periods of time, the rust is actually a good conductor. PolyPhaser and Transtector provide high-quality RF, AC, DC, EMP, and PoE / Dataline surge protection solutions and enclosures for mission-critical networks worldwide.The technical webinar with Jason Mies, from, Transtector PolyPhaser addresses the key elements of a surge protection system with emphasis on protecting sensitive electronics. When you subscribe, you receive only messages for Document Number PEN1011:Does your equipment room have a single point ground? Copper strap has lower inductance per unit length and more surface area in contact with conductive soil than the equivalent amount of copper in a circular conductor. * Proper grounding and bonding techniques required; see tech page for more information. Go to: http://home1.gte.net/res0958z/ to see my installation. The bulkhead panel has a weather protected built-in grounding kit that will handle a wide range of coax lines. The use of joint compounds further enhances the weather tightness of the bond. The strike energy is picked off and diverted into the ground system in a controlled way. xSn1o2>qGwAp!M~o=vFzj f^oi8]!;BLFn, 2n,d9>'GSa)>u`{DJ}k>Nop9lMT,19OWb^];]Yv3f_LWG)&kR^"r@WC31pcsJ4UFfTz/TItRHvSnZ~%DaG;u,$mS+FZiI"5G3FiMoF{]s%MtTY'B^ JUp,f9-B~gCu-|{{|RG!OD3endstream +1.208.772.8515 | www.polyphaser.com. i am looking at Polyphaser for an RF surge protector. Remember that surge energy can enter your shack in either of two ways: from a strike down the road coming in on the power/telephone lines or from a strike to your tower. Such currents following a round-member conductor will not make extensive use of its large cross sectional area. Dusty 25 yr old garage stored Diamond D-130 antennas still usable? This is why maintenance testing is important. Copper as a metal is a good electrical conductor, only moderately attacked by ground and air borne acids, and should have a life span measured in years. The added turns can also act like an air wound transformer coupling more energy into the line. Copper strap radials have been proven successful on bare mountain top solar powered sites where ground rods could not be used. With three copper straps the voltage would be even lower. A PolyPhaser bulkhead entrance panel provides all of the necessary attributes required above. The preferable alternative is to allow all racks to rise and fall with the overhead ground system potential without any other paths to ground. Customer must apply PolyPhaser's Weather Proofing Kit (Part Number: WK-1) to seal the unit and cable connections. In 90% of the strikes, a traffic jam of electrons will be coming down your tower. A good source for more information on GPR is: www.gpr-experts.com Last Reviewed: 1/7/03. An old timer once told me that he tested a ground by disconnecting it from everything and connecting it to power hot through a 30 amp fuse. If a ham has not had satisfactory results, HE HAS DONE SOMETHING WRONG. The breakdown path will produce a large voltage drop and magnetic fields inside the cabinet which are likely to destroy components. This will minimize l/O to-l/O current flow. This is best accomplished using an exothermic process. I see that they have many models. The power line to the transmitter is protected and grounded at the distribution panel where the power line enters the building. Antenna Support: I have 2 questions. Solutions PolyPhaser leads the market with its patented RF protection solutions, specifically supporting communications systems. Document Number PEN1024: Multiple I/O port protection,Single Point Ground considerationsNotes:One of the basic ideas in developing a protection strategy is not allowing stray energy to flow through the equipment. Outside world means any other ground outside of the lightning strikes local sphere of influence. Installation hardware installation instructions. The single point ground system will keep all the I/O protectors at the same level with respect to each other. Install additional bare radial lines with ground rods which will effectively parallel the inductance and reduce the overall system inductance. PolyPhaser's VHF50HN-ME is coaxial rf surge protector in the surge protection modules, surge suppressors category. The panel is best located near the ground to keep the inductance of the ground conductor low. PolyPhaserleads the market with its patented RF protection solutions, specifically supporting communications systems. Joints between copper radials and copper clad rods should be made by exothermic welds or by using joint compounds in high compression clamps. Further corrosion reduction of the rebar, due to galvanic action, will be limited by this oxide layer. Nothing can stop a lightning strike! The average current is about 18,000 amps for the first pulse, then dropping to half that value for the second and third pulses. For nearly forty years PolyPhasers focus-on-the future business philosophy has been the cornerstone of its success. However, a few poorly implemented occurrences can give a valuable technique a bad reputation. If the interconnect path is better (lower inductance and resistance) the majority of the current will bypass the house wiring. Even if abraded, it will reform and protect the metal from any further corrosion. In this case, due to the poor nature of the tower ground system, each of these J-bolts will actually share a significant amount of strike current which in turn will flow through the concrete. Since the strap is flat, its susceptibility to magnetic fields is only towards its edges. Mount the PolyPhaser Surge Arrestor on the inside wall, near the MIM-LINK unit and near the floor. This may be many meters from earth and the inductance/ resistance voltage drop will be very large (hundreds of thousands of volts). The inductance of the 10 foot horizontal coax run and ground bar to earth ground is 3.88uH (3.9uH rounded for simplicity). Most metals today are not perfectly pure and consequently, when exposed to the environment, will begin to exhibit some of effects of corrosion. Three Techniques: Every conductor has measurable inductance. Any dulling, graying, or blacking that may subsequently appear is a result of pollutant accumulation. No one should consider using a non-conductive structure for an antenna support. They will provide added protection for jointly used equipment such as answering machines, appliances and etc. This gives some percentage of improvement but it still must interconnect to conductive soil where it has both salts and moisture. An aluminum roof after 30-years only had 0.076mm (0.003 inch) average pitting depth. This will be a very low current unless another path is found by these streamers. The other is to measure the system. 6 0 obj This interconnection should be below grade and with a bare low inductance conductor. 3 kA surge 0.5uJ throughput energy. The l/Os must be protected and the protectors must be located and bonded together. The coil shunts the energy to ground all right, but it is at the wrong place. Whenever DC power needs to be inserted into an AC signal to power remote antenna amplifiers or other devices, a Bias-T connector is required. An alternative to the single point ground plate is to use a rack panel. If the outside (tower/perimeter) ground has a low impedance at lightning frequencies, most of the strike energy will be dispersed into the ground and little energy will enter the shack. It may not display this or other websites correctly. The better the ground plane for RF, the better the earthing for lightning. The speed, or transient response, of the ground system would be dependent on the combined inductance of the below grade conductive components and the resistivity/conductivity of the soil shunting those components. Second, the individual l/O protectors need to be co-located on the same electrical ground plane. Each coaxial line as it enters the building is attached to the panel with an additional ground kit before connecting to a protector. 2) Soil Doping: Once at the equipment, the current will follow the chassis to the safety ground. Copper strapping is preferred over large diameter wire as an inter-connecting media. A complicating factor is that the other l/O protectors are at a distance with respect to the equipment. Grounding the antenna line and not disconnecting the coax shield can still allow strike energy to be shared with the equipment The shield connects to the chassis and if a single point ground is not present with power/telephone protectors, the equipment will be damaged. Another complication in this scenario is the inductance of the conductor between the I/O protector and the ground system. I have an end fed wire connected to the HF antenna port and a Telewave discone connected to the VHF/UHF port. Buried underground, it will not be hit directly, but if a nearby tree is hit, the amount of energy coupled through the conductive ground medium can be almost equal to a direct hit. It is a good idea to bond (ground) all conductive objects within 1 meter of any single point earthed equipment in the room. Plain and simple. The primary problem here is the low surface-area contact of the round wire with the (round) tower leg. The ground system can absorb only so much energy before it becomes saturated. Lightning has a large magnetic field associated with its typical high current pulse. Since the surface area interface between the J-bolts and the concrete is small, and the surge current density from the strike very large, the corresponding heat generated by the energy transfer can turn the concrete moisture into steam and possibly crack the pad. The site will be something of which everyone involved can be proud to say they were a part. The strength of a magnetic field diminishes at the rate of one over the distance squared. to a product via email. The strike energy, like water, will follow the easiest (least inductive) path to ground. The velocity factor of the coaxial cable center conductor with a fast rise time pulse can vary from 66 to 90% the speed of light. Despite the formation of the green patina, copper has been used for centuries and has negligible rates of corrosion in unpolluted water and air. However, be aware that stainless steel is not a very good conductor. The local elevated potential would seek to equalize the signal conductor through your circuitry, and use it as a path to a lower potential. The common practice of bringing the antenna cable into the top of the cabinet and securing (bolting) the cabinet to the floor could damage the equipment. I lost a television, 3 cable boxes, and the upper left part of my circuit box in the garage was toasted. By being underground, the shielding effect to the wires is not great. Similarly, ground conductors exhibit normal inductance before they go below grade. Stay away from gels and other chemicals that can shorten conductor life. I do suggest that if you use it for microwave applications or where you have DC power on the coax (1270 MHz systems) that you carefully select the voltage and polarity rating of the protector and if you need a seperate injection tap.