"Grounding: down to earth comments!"

RARS Meeting August 2009

Reasons for GroundingSafetyPerformance

SafetyMinimize touch potential.Provide a low impedance path to clear phase to ground electrical power circuit faults.

PerformanceEqualize potential differences to prevent or mitigate unwanted coupling, instability, radiation, etc.

Reasons for Grounding a Radio StationMinimize touch potential.

http://www.nppa.org/professional_development/self-training_resources/look_up_report/Touch%20Potential-1.jpg

Reasons for Grounding a Radio StationMinimize touch potential.Equalize potential differences to prevent or mitigate unwanted coupling, instability, radiation, etc.

Reasons for Grounding a Radio StationMinimize touch potential.Equalize potential differences to prevent or mitigate unwanted coupling, instability, radiation, etc.Prevent damage to the station from lightning discharges.

The BasicsE (voltage) = I (current) x R (resistance)If I = 0, then E = 0.If R = 0, then E = 0.

If E1 = E2, then the potential difference between E1 and E2 is 0, therefore the current that flows in a resistance between E1 and E2 is 0.

BondingTo prevent station damage, one must equalize voltage differences caused by lightning discharges.

Bonding is the means by which the potential difference between conductive elements is made to be 0 volts.

Grounding When either an individual conductive element, or a system of elements, is at the same potential difference as the earth, they are said to be grounded and at equal-potential to the earth.

Grounding is achieved through bonding of a system of elements to a grounding electrode.

Grounding Electrode A conductive element that is in contact with the earth is a grounding electrode.

Typical examples of a grounding electrode:Ground rod.Metallic underground water pipe.Ground ring.

http://www.dranetz-bmi.com/pdf/groundtesting.pdf

Grounding Electrode ConductorThe wire that connects (bonds) the ground rod to another element of the grounding system.

Building a Grounding SystemGrounding Electrode (reference to earth)

Building a Grounding SystemGrounding Electrode (reference to earth)Grounding Electrode System

Building a Grounding SystemGrounding Electrode (reference to earth)Grounding Electrode SystemGrounding Electrode Bonding Conductors

Building a Grounding SystemGrounding Electrode (reference to earth)Grounding Electrode SystemGrounding Electrode Bonding ConductorsGrounding Electrode Conductor

Building a Grounding SystemGrounding Electrode (reference to earth)Grounding Electrode SystemGrounding Electrode Bonding ConductorsGrounding Electrode ConductorMain Ground Bar

Building a Grounding SystemGrounding Electrode (reference to earth)Grounding Electrode SystemGrounding Electrode Bonding ConductorsGrounding Electrode ConductorMain Ground BarBonding Conductors

http://www.astrosurf.com/luxorion/qsl-lightning-protection4.htm

Questions

Referenceshttp://www.nppa.org National Press Photographers Associationhttp://www.dranetz-bmi.com Dranetz-BMI http://www.astrosurf.com French Astronomy Web-site

To learn more:Lightning Protection for the Amateur Radio Station Ron Block, KB2UYThttp://www.arrl.org/tis/info/pdf/0206056.pdf Part 1, QST, Jun. 2002 http://www.arrl.org/tis/info/pdf/0207048.pdf Part 2, QST, Jul. 2002 http://www.arrl.org/tis/info/pdf/0208053.pdf Part 3, QST, Aug. 2002

Getting Down to Earthhttp://www.biddlemegger.com/biddle-ug/GettingDownToEarth-MC.pdf One of numerous application guides found at BiddleMeggar.com

All About Lightninghttp://www.astrosurf.com/luxorion/qsl-lightning-protection4.htm

To learn more:MIL-HDBK-419A - MILITARY HANDBOOKGROUNDING, BONDING, AND SHIELDING FOR ELECTRONIC EQUIPMENTS AND FACILITIES VOLUME 1 OF 2 VOLUMES - BASIC THEORYVOLUME II OF 2 VOLUMES APPLICATIONS

TM 5-811-3/AFM 88-9 - TECHNICAL MANUALELECTRICAL DESIGN - LIGHTNING AND STATIC ELECTRICITY PROTECTION

Available for FREE download from: http://www.everyspec.com/

And http://140.194.76.129/publications/Publications of the Headquarters, United States Army Corps of Engineers

*There are two kinds of grounds; safety grounds and performance grounds.*Explain touch potential and show an illustration.*Unwanted coupling Instability self-oscillationRadiation ungrounded shielded cable**R.F. burns hurt.*The lightning discharges may be direct or indirect.****Show an acceptable ground rod.*Give a basic explanation of virtual earth. Maybe show a slide with the explanation. **http://www.maplenet-inc.com/grounding