Presentation on theme: "Radio Works R.F. Consulting Presents Grounding and Bonding A 3 Dimensional Aproach www.RadioWorksRFConsulting.comwww.RadioWorksRFConsulting.com 561-969-9245."— Presentation transcript:
Radio Works R.F. Consulting Presents Grounding and Bonding A 3 Dimensional Aproach www.RadioWorksRFConsulting.comwww.RadioWorksRFConsulting.com 561-969-9245 Copyright 2009, All Rights Reserved
Opening Conventions Conversely Grounding Is A Religion Grounding Is A Lot Of Subjects Under One Header Avoid The Strike Minimize The Strike Control The Damage Downward Dissipation The Design The Theory AC Mains Strike Potential Grounding Entities: Tower, Cable Portal, Mains, Shelter Implementation Inspection Maintenance Conclusion Chapter Topics:
Introducing New Concepts 3 Dimensional Electrical Schematics The Entity Concept Impedance VS. Resistance Throwing Charges The Reality of Grounds ( Yours and Theirs ) Dispelling Myths
OPENING: Change is not necessary or relevant for all things. Change is the evolution of an idea that has been developed and has reached a point where some form of need, requirement, growth or progress mandates that new ideas be considered. It is this consideration that promotes change.
Convention: We have done “it” this way for decades, made few significant changes, killed low numbers of people, and have had “some” success with the way we do “it”, Why change now? This obviously applies to every thing in every day life.
Conversely: We have seen many changes in the global grounding scenario as evidenced by the multitude of educational grounding primer documents and de-facto standards that claim there is enough data, if not history, to recommend changes in this time honored methodology. ( A supposition ) Practices are also held tightly to the convention of the writer of a particular document.
Grounding Is A Religion: Though a provocative statement, this is a stereotypically accurate statement. “It” can be allowed that no singular methodology is wholly correct Conventional thought also has to be understood that every situation is different Corporate methodologies protect themselves at our expense and are driven by liability and the ramifications of exposure and indemnification
Grounding Is A Lot Of Subjects Under One Header: Grounding as a descriptive activity, regardless of the method, and the assumption that the purveyor has no axe to grind, and selflessly promotes the intention to protect equipment and personnel from damage due to lightning strike, or other electrical fault Avoid the “Strike”. Minimize the strike Control the strike and any potential for damage
Downward Dissipation: The key word is Downward, the un-tamed strike energy radiates both downward and outward (spherically) from a surface point strike or energization Over zealous bonding of every metallic thing to every other metallic thing causes damage in the worst way. It is impossible to sufficiently bond objects together so as to eliminate the action of circulating currents during a strike event. It is these circulating currents that cause the primary damage.
The Design: As each site is different, so each site is the same A properly designed dissipative array is purposed to direct the strike energy developed from the tower “Downward” in to the earth, and away from the shelter horizontally and vertically Proper design of the grounding applications of the various electrical and radio related conductors descending from the tower also assist the strike in a controlled way on the downward and directedely outward path
Three Dimensional Electrical Schematics and Design Criteria Grounding is NOT and NEVER WAS a two dimensional problem Let’s face it, It is not 1930 any more Grounding, Bonding, Circulating Current Flow, Charge Dissipation, and Strike Avoidance ARE a THREE DIMENSIONAL consideration. Everyone who believes that it is good to turn your Racks and Transmitters in to large fuses Raise your hands
The Theory: Remove the circulating current paths and everything in the room stands up with a potential rise and once dissipated milliseconds later, it all sits back down un-touched Without circulating paths, there is no current flow With no I/R losses there is no voltage drop With no voltage drop, there is no dissipation of current With no dissipation, there is no heating, arcing or burning
Resistance VS. Impedance Virtually anyone with an ounce of sense can drive a ground system with less than 5 Ohms Poorly located and interconnected low resistance paths can cause more trouble than they cure Use of Low and High Impedance paths assist in the segregation of surge/strike energy in concert with the proper placement of low Resistance ground arrays
AC Mains: Regardless of the spike source, limiting of the spike voltage is essential to minimizing the damage to the equipment in the shelter The two basic types of Mains surge arresting are series inserted devices and parallel devices Series devices are more effective than parallel devices
Strike Potential: Entry of the strike energy into the shelter must be avoided The AC Mains protective system can assist with this imparted energy but only if it is impressed on to the Mains conductors Entry of strike energy in to a shelter system through the grounding system and devices in mechanical contact with the floor that causes another significant source of damage is called the Reverse Burst
Grounding Entities: The Tower The Cable Portal The AC Mains The Shelter Enter the Single Point or Star ground. In a physical plant the size of any transmitter facility, whether simple cellular or broadcast, the idea of a true single point is almost not possible. The modification of design called… The Distributed Single Point System
Implementation: Develop a comprehensive plan for all Entities as they ground themselves, and relate to each other Develop interconnectivity utilizing high and low resistance in concert with high and low inductance Develop a testing standard that is repeatable Perform maintenance testing
Throwing Strike Energy Proper system design segregates strike energy to control its effects Strike energy impressed on to an Entity within the system is dissipated by that system and is not shared outside that system Proper design of the dissipative array will “Throw” the charge directionally in vertical and horizontal dimensions
Inspection: It is important to be able to inspect, log and repeat testing of the effectiveness of the design Use the proper testing apparatus Repair any defect immediately A damaged grounding system is a dangerous defect and must be regarded as such
Primary Testing Devices High Current/High Noise Clamp On Single Ended 3 Point Of Fall
Maintenance: In this care and feeding we see that it is possible for even the best design to fail at some point either through the application of overwhelming energy or in the performance of it’s duty It is often noted that simple decay will deteriorate any grounding system Electrical and visual inspection regimens will surface any deficiencies before they become issues during the next strike event
Example of XL Spread Sheet From Post installation Testing
Conclusion: It is not as important what you tend to believe or what is fact or fiction. The proof of the matter is that certain techniques work and others are simply ineffective or downright dangerous to materiel or personnel Simply because we as a group have done “it” a certain way for ever, is not a good reason to continue to do this or any type of thing Bold steps need to be taken to create a more unified and appropriate convention that allows the designers and users the assuredness that a system was specifically and appropriately designed for them and favors none other than them
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