GROUNDING 3 Dissipate the energy into a low

GROUNDING 3. Dissipate the energy into a low impedance grounding system. 4. Bond all ground points together to eliminate ground loops and create an equipotential plane.

Why do we ground? • Personnel Safety - Reduce potential differences between non-current carrying parts (enclosures) and between non-current carrying parts and Earth. • System stability - Operate over current device during a ground fault. • Protect equipment - Over voltage control. - Lightning Dissipation - ESD (Electrostatic Discharge) • Reliability of Equipment - Noise Control (Computer Grounding, SRG)

Guidelines / Rules International Electro technical Commission (IEC) Underwriters Laboratory (UL) National Fire Protection Association (NFPA) American National Standards Institute (ANSI) British Standards (BS) Mine Health Safety Health Administration (MSHA) Institute of Electrical & Electronic Engineers (IEEE) Occupational Safety Health Administration (OSHA) Telecommunication Industry Association (TIA) European Committee for Electro Technical Standardization (CENELEC)

What is a good ground? Ideally, zero ohms resistance • Some standards require a single electrode, of specified dimensions • Others want a figure below a specified value • NEC < 25 • Telecom < 5 • Power < 1 • Combination of the above Goal is practical and dependant on governing factors • Physical limitations of the site • An economic solution

Characteristics A good grounding system: • has a low resistance path into ground. • The lower the resistance the more likely lightning, surge and fault currents will flow safely to and dissipated to ground • does not deteriorate over time. • A grounding system must resist corrosion and be capable of repeatedly carrying high currents. Typically, a life in excess of 30 years!

Grounding Design When designing the grounding system, we must consider each of the components as part of a chain: • • • Soil Electrode to soil Electrode Connector Ground Conductor

Grounding Chain SOIL • Soil resistivity must be carefully considered, including moisture content temperature and seasons. • Resistivity is measured to determine information necessary to design and build an electrode system • Bore samples confirm sub-strata composition • Usually measure resistivity using the Wenner method (developed in 1915 by Frank Wenner)

Grounding Design For any design, we need to establish the parameters: • Required ground resistance; • From standard or specified by client • Soil resistivity; • At least 2 measurements at 90 degrees • Many measurements at different spacings • Bore hole survey of site • Site area and limitations (drawings) • Property outline • Existing structures, paved areas • Buried pipes and services

Resistivity Also known as specific resistance: • Physical characteristic of the material • • Copper = 1. 72 x 10 -8 ohm. m GEM = 0. 12 ohm. m Bentonite = 2. 5 ohm. m (typical) Concrete = 30 to 90 ohm. m Sand (moist) = 300 ohm. m Gravel (moist) = 500 ohm. m Sand (dry) = 1000 ohm. m Stoney soil = 30, 000 ohm. m

Grounding Chain ELECTRODE TO SOIL

Grounding Chain GROUND ENHANCEMENT • Chemicals (salts) • Calcium Chloride or Sodium Chloride • Bentonite • Hydrous Aluminium Silicates • GEM ® & E-Gel • Proprietary Formulations

Grounding Chain CHEMICALS (SALTS) • Leach into environment (pollution) • Accelerate corrosion • Maintenance replacement issue

Grounding Chain BENTONITE • • Requires moisture to form electrolyte Effective when wet Low initial cost May pull away from rod or soil when it dries

Grounding Chain GEM • • Very effective - conducts wet or dry 20 times more conductive than Bentonite Provides seasonal stability – sets hard Easy to use • 12 kilogram bags • Install wet or dry • Design software available

Grounding Chain ELECTRODE-TO-SOIL Ground rod resistance is affected by length, relative placement, and most importantly, coupling integrity where rods are joined for deep driving.

GROUND RODS (Electrodes) Material Choices

GROUND RODS (Electrodes) Materials are selected for corrosion resistance: • Galvanised steel rods are cheap but have a relatively short service life • Solid copper and stainless steel rods have a long service life but are considerably more expensive • Copperbonded earth rods are less expensive than solid copper and can be deep driven

GROUND RODS (Electrodes) International standards require a minimum of 0. 25 mm copper on a Copperbonded rod ERITECH bonded rod • Requirement of BS 7430; UL 467 • Copper specimens buried in 43 soil types for 8 -13 yrs • Calculated average penetration in 30 years would be 0. 17 mm in 41 of the 43 different soils • Base on this, 0. 25 mm established as minimum Typical sheathed rod

GROUND RODS (Electrodes) • • Ground rods can be coupled to achieve greater depth, using either: • Compression couplings • Threaded couplings A driving head can be used to prevent head deformation.

GROUND RODS (Electrodes) Comparison of life expectancy

Grounding Chain CONNECTOR Connections must maintain the integrity of the conductor and the system as a whole for up to 40 years. They must be of an appropriate material and mass to: • carry prospective fault currents • be able to resist corrosion • maintain original low resistance

Grounding Chain MECHANICAL CONNECTOR Although quick to apply, suffer from the following disadvantages: • Tends to loosen • Corrosion in the connection interface

Introduction to Cadweld Molecular Bond There is no mechanical interface in a molecular bond. Molecular bonds guarantee conductivity across the entire section

Introduction to CADWELD Mechanical joints will deteriorate over time and if not maintained, eventually fail.

Introduction to Cadweld – a process to make exothermic welded connections Exothermic – a chemical reaction which gives off heat as the reaction takes place 3 Cu 2 O + 2 Al 6 Cu + Al 2 O 3 + Heat (2537 o. C) Cadweld provides a simple on site welding connection without requiring external power, equipment or special training normally associated with welding or brazing

Introduction to Cadweld

Introduction to Cadweld Eliminate Connections The process can be used to splice conductors, make “T” connections and “cross overs” as well as connections to ground rods, ladder trays, rebar, rail and steel structure.

Introduction to Cadweld CADWELD CONNECTION Completely continuous solid welded copper connection

Introduction to Cadweld Life of the mold A mold will generally last for 50 connections. However: • RSA, NSW, Australia 70 mm 2 bonds to rail head = 250 connections • GV Kinsman, Australia tramway bonds = 300 connections Extend mold life, clean only with soft natural bristle brush, clean cloth, or newspaper.

Introduction to Cadweld The Process • The weld metal is supplied in a plastic canister. It contains a precise measure by weight. • Packed in the base of the canister is also a measure of starting material. • Weld metal does not age, it’s shelf life is unlimited. Note: No phosphorous is used in CADWELD. Materials are harmless and non toxic.

Introduction to Cadweld How is a CADWELD Connection done?

Introduction to Cadweld Technical Advantages No de-rating - The current carrying capacity (fusing) is equal to the conductor (see photos). ü Lasts the life of the conductor - The joint will not deteriorate with age. It is permanent. ü Can not loosen - There is no mechanical interface. The joint is a molecular bond. ü Does not corrode – The joint is unaffected by corrosive products to the same degree as copper ü Resistance does not increase – The connection will withstand repeated faults without deterioration ü

Mechanical Connector

Crimp Connector

CADWELD Connection Ontario Hydro Report

Introduction to Cadweld User Benefits ü ü ü Simple to use – Minimal training is required. One connection is sufficient operating under supervision. Visual inspection – The quality of the joint can be confirmed by eye. Every connection! Light & portable - The components, including accessories can be carried easily by one person. No external power or heat – The reaction is self contained. There are no hoses or leads to trail around. Versatile – Used to weld copper, copper alloys, copper bonded steel, steel alloys including stainless steel.

Introduction to Cadweld Use Cadweld when there is a need for: ü ü ü ü Conductivity Corrosion resistance Overload withstand Reliability and long life Small space available Large conductors Compliance with IEEE 80 & 837

A new system for delivering CADWELD connections, featuring u Electronic ignition u Prepackaged weldmetal

The Process CADWELD is Now Even Easier to Use with the Latest Advancement in the Continuing Evolution of ERICO’s Exothermic Products

Simplified Method of Completing Exothermic Welded Electrical Connections

The system u Utilizes Integrated Tamper Proof, Disposable, Moisture Resistant Weld Metal Package u Weld Metal, Disk and Ignition Source are All Incorporated into Weld Metal Package

Part Numbers CADWELD PLUS (F 20)

Short Video Long Video

Grounding Chain Grounding Conductor • Material (conductivity & corrosion resistance) ü Copper, Copperweld, galvanized steel, ü Aluminum (above ground and insulated) • Size (cross sectional area / impedance) ü Sufficient to withstand maximum fault current for maximum clearing time

Grounding Chain * Copper conductor, at 0. 5 sec the impact of connector choice is: mm 2 Cadweld 1083 C Brazed 450 C Pressure 350 C Pressure 250 C 35 13. 7 k. A 10. 6 9. 7 8. 4 50 19. 9 15. 2 13. 8 12. 0 70 27. 9 21. 3 19. 3 16. 8 95 37. 8 28. 9 26. 2 22. 8 A I= K× S 120 47. 8 36. 5 33. 1 28. 8 240 95. 6 73. 0 66. 3 57. 5

Grounding Chain * When the decision on conductor size is made, the type of connector is part of that process • Mechanical connectors passing IEEE 837 can be rated equivalent to the conductor (1083 C) • These connectors still fall short of Cadweld for performance equivalent to the conductor. Refer: Ontario Hydro Technologies Report C-95 -EST-193 -P & Southern Electric International Project C 94901

Grounding Design Calculating resistance to ground from IEEE 142

Grounding Design For a more complex design, we need to advised of some additional parameters: • Size of fault current; • Clearing time of protection; • Existing grounding systems • Material and components preferences • Standard conductor sizes • Deep driven rods (bore hole) • Horizontal radials extending outside property line (acceptable? )

Field Data Design Program – Win IGS Can model soil conditions • Based on measurements using the Wenner 4 point method • Requires survey of area • 2 directions at 90 degrees • More measurements is better

Soil Parameter Report Design Program – Win IGS Can model soil conditions • A 2 layer soil resistivity model is produced • Parameters / level of confidence in the result is noted

Plan View Drawings developed within Win. IGS According to the: • area available, • ground analysis and • design calculations

3 D model Drawings developed within Win. IGS According to the: • area available, • ground analysis and • design calculations

Customer Drawings CAD Drawings are produced More detail added: • accessories (pits, etc) • bill of materials • installation notes • expand design for poor soil types covering multiple sites

Wind Farm 1 B

Expanded Designs II Basic design, all towers 3 B, 500 (40’)/ 1, 000 ohm. m

Bill of Materials

Bond (Connect) Grounds Together 4. Bond all ground points together to eliminate ground loops and create an equipotential plane.

Bond (Connect) Grounds Grounding Design Together Older designs, have independent grounding systems. The more recent trend is to bond all the ground systems.

Addn risk of electromagnetic induction along route of internal earth lead Multiple Point of Entry Single Point of Entry

Bond (Connect) Grounds Together When normal operating conditions dictate that equipment grounds remain isolated, a Potential Equalisation Clamp (PEC) can be used for this purpose.

QUESTION TIME