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Grounding for Amateur Radio Grounding for Amateur Radio

Grounding for Amateur Radio - PowerPoint Presentation

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Grounding for Amateur Radio - PPT Presentation

Harold C Fleischer III AE5AS 8262017 1 Ohms Law V I x R Voltage Current x Resistance 8262017 Grounding For Amateur Radio 2 Ohms Law V I x R Voltage Current x Resistance ID: 741005

radio grounding ground amateur grounding radio amateur ground current 2017 voltage 2017grounding battery resistance rod impedance basic capacitance equipment circuit rods wire

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Slide1

GroundingforAmateur Radio

Harold C. Fleischer, IIIAE5AS

8/26/2017

1Slide2

Ohm’s Law

V = I x RVoltage = Current x Resistance

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Grounding For Amateur Radio

2Slide3

Ohm’s Law

V = I x RVoltage = Current x Resistance

V = I x ZVoltage = Current x Impedance

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3Slide4

Ohm’s Law

V = I x RVoltage = Current x Resistance

V = I x ZVoltage = Current x Impedance

V = ((1/C)

i

dt

) + (

i

x R) + ( L x (di/

dt

) )

Voltage = Capacitance divided into the integral of Current over time

+ Current times Resistance + Inductance times the derivative of Current over timeThis equation is why imaginary numbers and polar coordinate mathematics appear in the license examination for Amateur Extra.

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Grounding For Amateur Radio

4Slide5

Battery and Voltage

8/26/2017Grounding For Amateur Radio

5

Battery

+

-

Voltage

No Impedance

No CurrentSlide6

Basic Complete Circuit

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6

Battery

+

-

Voltage

Impedance

Current ExistsSlide7

Short Circuit

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7

Battery

+

-

Voltage

Current

Infinite

No ImpedanceSlide8

Open Circuit

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8

Battery

+

-

Voltage

No Current

No ImpedanceSlide9

Basic Capacitance Circuit

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9

Battery

+

-

Voltage

Capacitance

DC – No CurrentSlide10

Basic Capacitance Circuit

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10

Battery

+

-

Voltage

Capacitance

DC – No Current

Can Current jump the gap in a capacitor?Slide11

Basic Capacitance Circuit

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11

Battery

+

-

Voltage

Capacitance

DC – No Current

Can Current jump the gap in a capacitor?

Yes, capacitors have a breakdown voltage.Slide12

Can Electrons Jump Air Gaps?

8/26/2017Grounding For Amateur Radio

12

Battery

+

-

Voltage

Spark Plug

Current

Yes, spark plugs in a car, etc., are all about jumping an air gap to create a spark.Slide13

Lightning Jumps Air Gaps

8/26/2017Grounding For Amateur Radio

13

When Voltage from static electricity gets high enough, electrons will jump the gap and produce thunder and lightning

+

-

Voltage

Currents will be brief, but very high.

GroundSlide14

Electrons Always Wantto go to Ground

8/26/2017Grounding For Amateur Radio

14

+

-

Voltage

Ground

Radio Transceiver

+

-

VoltageSlide15

Basic Ground Problem

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15

Battery

+

-

Voltage

Impedance

Current Exists

-

Ground

V

m

V

c0

V

g

If V

c0

does not equal V

g

, Electrons want to get to ground.Slide16

Basic Electrocution Problem

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16

Battery

+

-

Voltage

Impedance

Current Exists

-

Ground

V

m

V

c0

V

gSlide17

Basic Grounding Solution

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17

Battery

+

-

Voltage

Impedance

Current Exists

-

Ground

V

m

V

c0

V

g

V

c0

= V

g

, and you are no longer the best path to ground.

Grounding WireSlide18

Basic Grounding Truth

Grounding is like PregnancyYou are Grounded or you are not Grounded.There is no such thing as partially Grounded.Ideally, you have a Ground when the ground resistance value is 0 ohms.

NEC requires a ground resistance value of <25 ohms.NEC recommends a ground resistance value of 5 ohms or less for sensitive equipment.Type of soil affects what you have to do to get a good ground resistance value.

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Grounding For Amateur Radio

18Slide19

Ground Resistance Measurements

Very complicated; not necessarily inexpensive.Must drive ground rod and then other rods to do measurements.Meters can cost upwards of $200-$300.

The default is to follow the NEC.Install ground rods or ground plates.

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19Slide20

Grounding Rods and Plates

Grounding Rod must be:Copper or copper clad aluminum.At least 8’ long with only 3” showing.

At no more than an angle of 45 degrees when driven in.Measuring Ground Resistance is complicated.Mechanical Clamp of AWG 6 copper wire or braid.

(A high current will melt solder.)

Grounding Rod may be placed horizontal in a 30” deep trench if they can not be installed vertically.

Grounding Plate must be:

2 feet square ( 1’ x 1’ x 2 sides).

¼” thick if ferrous, 1/16” thick if non-ferrous.

Hole in center for bolt, nut, and lock washer.

Top of plate must be 5’ below the surface of the ground.

(The more square feet in the plate, the more likely Ground Resistance measurement objectives will be met.)

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20Slide21

Grounding in a House

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21

Panel

Meter

Black – Hot

White – Neutral

Green - Ground

Grounding Wire

Grounding RodSlide22

Example of a House Ground

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22

Grounding wire

in protective coverSlide23

Bonding

Bonding is GroundingBonding is tying equipment together to eliminate or dampen inter component electrical interaction: Noise

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23Slide24

Number of Groundsfor your Property

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24

ONESlide25

Multiple Grounding Rods- One Ground

Shortest Path mattersGround from Meter/Panel goes straight down to Grounding RodGround from Antenna needs to go straight down even if antenna feed cable has to make a turn to the “Radio Shack

Ground from “Radio Shack” needs to go straight downGround from Tower needs to go straight downTie all ground rounds together with AWG 3/0 buried 18” deep.

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25Slide26

Grounding Example

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26Slide27

Grounding Example

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27

Example of Lightning Arrestor (Surge Protector) at bottom of drip loop.Slide28

Grounding Example Site Plan

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28

Patio

House

Grounding Rod

Grounding Rod

18” Trench with Grounding Cable

Remember: Number of Grounds on Your Property?

ONE

VHF/UHF Antenna

HF AntennaSlide29

Grounding with Tower Example

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29

Patio

House

(with no antennas mounted on it)

Grounding Rod

(Radio Shack bonding)

Grounding Rod

(Electrical

Service)

18” Trenches with Grounding Cable

Remember: Number of Grounds on Your Property?

ONE

Tower Bonded to Antenna, Each Leg with Grounding Rod, Leg Grounding Rods 6’ apart, & Leg Grounding Rods joined by Ground Wire 1’ deep

6’Slide30

Emergency Generators

OSHA Fact SheetFrame of portable generator may serve as ground if:Generator supplies only equipment mounted on it or cord connected equipment through receptacles mounted on it.

Non-current metal parts of equipment are bonded to the frame and grounding conductor terminals are grounded to the frame.Do not connect a generator to a structure except through a transfer switch.

Very sensitive situation that may require generator to be grounded.

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30Slide31

Review

You ground to:Protect against an electrical faultProtect against lightningSuppress noise in electrical equipment

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31Slide32

ReferencesARRL Handbook, Chapter 28.1, 91

st Edition, 2014.Silver, H. Ward, N0AX, Grounding and Bonding for the Radio Amateur, ARRL, 2017. Morgan, Jennifer, and

Chusid, Michael, Lightning Protection for the Amateur Radio Operator’s Home, QST, ARRL, June 2017.

CECOM TR-96-2, Earth Grounding Pamphlet, May 1996.

OHSA Fact Sheet: Grounding Requirements for Portable Generators,

DSTM 10/2005.

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32