# Electric Grounding Grounding down to earth comments RARS Meeting – August 2009

Document Sample

```					"Grounding: down to earth

RARS Meeting – August 2009
Reasons for Grounding

• Safety
• Performance
Safety

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

•   Equalize potential differences to prevent
or mitigate unwanted coupling, instability,
Reasons for Grounding a Radio Station

•   Minimize touch potential.
http://www.nppa.org/professional_development/self-training_resources/look_up_report/Touch%20Potential-1.jpg
Reasons for Grounding a Radio Station

•   Minimize touch potential.
•   Equalize potential differences to prevent
or mitigate unwanted coupling, instability,
Reasons for Grounding a Radio Station

•   Minimize touch potential.
•   Equalize potential differences to prevent
or mitigate unwanted coupling, instability,
•   Prevent damage to the station from
lightning discharges.
The Basics
E (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.
Bonding
To 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 Conductor

The wire that connects (bonds) the ground rod to
another element of the grounding system.
Building a Grounding System
• Grounding Electrode (reference to earth)
Building a Grounding System
• Grounding Electrode (reference to earth)
• Grounding Electrode System
Building a Grounding System
• Grounding Electrode (reference to earth)
• Grounding Electrode System
• Grounding Electrode Bonding Conductors
Building a Grounding System
•   Grounding Electrode (reference to earth)
•   Grounding Electrode System
•   Grounding Electrode Bonding Conductors
•   Grounding Electrode Conductor
Building a Grounding System
•   Grounding Electrode (reference to earth)
•   Grounding Electrode System
•   Grounding Electrode Bonding Conductors
•   Grounding Electrode Conductor
•   Main Ground Bar
Building a Grounding System
•   Grounding Electrode (reference to earth)
•   Grounding Electrode System
•   Grounding Electrode Bonding Conductors
•   Grounding Electrode Conductor
•   Main Ground Bar
•   Bonding Conductors
http://www.astrosurf.com/luxorion/qsl-lightning-protection4.htm
Questions
References
• http://www.nppa.org National Press Photographers Association
• http://www.dranetz-bmi.com Dranetz-BMI
• http://www.astrosurf.com French Astronomy Web-site
Lightning Protection for the Amateur Radio Station –
Ron Block, KB2UYT
• http://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 Earth
http://www.biddlemegger.com/biddle-ug/GettingDownToEarth-MC.pdf
One of numerous application guides found at BiddleMeggar.com

http://www.astrosurf.com/luxorion/qsl-lightning-protection4.htm
MIL-HDBK-419A - MILITARY HANDBOOK
GROUNDING, BONDING, AND SHIELDING FOR ELECTRONIC
EQUIPMENTS AND FACILITIES
VOLUME 1 OF 2 VOLUMES - BASIC THEORY
VOLUME II OF 2 VOLUMES – APPLICATIONS

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