Perform Bonding And Earthing On 3 Kv Dc And 25 50kv Ac On Ohte Training

Objectives:
• Define bonding and earthing and explain their importance in OHTE systems.
• Identify key terminology and standards (SANS 10219, SANS 10142-1).
• Describe the hazards of electrical shock and arc flash.
• Explain the role of bonding and earthing in personnel safety and equipment protection.

Topics:
• Overview of OHTE systems: 3kV DC and 25/50kV AC.
• Basic electrical theory: voltage, current, resistance, and earth path.
• Difference between bonding and earthing.
• Relevant SAQA unit standards and legislative requirements.
• Safety precautions and risk assessment principles.
• Introduction to earth electrodes and earthing conductors.
• Case studies of earthing failures.

Objectives:
• Explain soil resistivity and its effect on earthing design.
• Describe types of earth electrodes (rods, plates, grids).
• Perform soil resistivity measurements using the Wenner method.
• Interpret soil resistivity data for earthing design.

Topics:
• Factors affecting soil resistivity: moisture, temperature, chemical content.
• Earth electrode configurations: rod, plate, ring, and grid.
• Step-by-step soil resistivity testing procedure.
• Calculation of earth resistance using formulae.
• Practical exercise: soil resistivity measurement.
• Recording and reporting test results.

Objectives:
• Calculate minimum cross-sectional area of earthing conductors per SANS 10142-1.
• Select appropriate conductor materials (copper, steel, galvanised).
• Install earthing conductors correctly, including connections and joints.
• Inspect and test conductor continuity.

Topics:
• Sizing criteria: fault current, duration, and thermal capacity.
• Material properties and corrosion considerations.
• Installation techniques: trenching, clamping, and bonding.
• Connection methods: exothermic welding, mechanical clamps, compression.
• Continuity testing using a low-resistance ohmmeter.
• Common installation defects and remedies.

Objectives:
• Identify all metallic parts requiring bonding in OHTE environments.
• Explain the purpose of equipotential bonding.
• Perform bonding connections to rails, towers, and equipment.
• Verify bond integrity using test instruments.

Topics:
• Bonding of rails, overhead line towers, and supporting structures.
• Equipotential bonding to prevent step and touch potentials.
• Bonding of switchgear, transformers, and surge arrestors.
• Bonding of cable sheaths and armouring.
• Use of bonding jumpers and flexible connectors.
• Testing bond resistance and continuity.

Objectives:
• Describe the unique earthing requirements for 3kV DC traction systems.
• Identify stray current corrosion risks and mitigation strategies.
• Install earthing for DC substations and trackwork.
• Test earthing system performance in DC environment.

Topics:
• DC traction system overview: substations, overhead line, return path.
• Stray current corrosion: causes and effects.
• Stray current collection systems and drainage bonds.
• Earthing of DC switchgear and rectifiers.
• Measurement of rail-to-earth potentials.
• Maintenance of DC earthing systems.

Objectives:
• Explain earthing requirements for 25/50kV AC overhead traction.
• Describe the function of earth wires and shield wires.
• Perform earthing of AC substations and autotransformers.
• Test touch and step potentials at AC installations.

Topics:
• AC traction system overview: feeding, return, and earthing.
• Earth wires on overhead lines: lightning protection and fault return.
• Earthing of autotransformers and booster transformers.
• Touch and step potential calculations and limits.
• Measurement of earth grid resistance.
• Safety clearances and isolation procedures.

Objectives:
• Explain lightning protection principles for OHTE.
• Select and install surge arrestors for 3kV DC and 25/50kV AC.
• Bond surge arrestors to earth system.
• Test surge arrestor operation and earthing connection.

Topics:
• Lightning strike mechanisms and risk assessment.
• Lightning protection zones and rolling sphere method.
• Surge arrestor types: metal oxide, gapped, and hybrid.
• Installation location and lead length optimisation.
• Bonding of arrestors to earth electrode.
• Periodic testing and maintenance of arrestors.

Objectives:
• Perform earth resistance testing using fall-of-potential method.
• Measure touch and step potentials.
• Conduct continuity and bond resistance tests.
• Document test results and compare with standards.

Topics:
• Earth resistance test equipment: clamp-on meter, 3-point tester.
• Fall-of-potential test procedure and interpretation.
• Touch and step potential measurement setup.
• Continuity testing of bonds and conductors.
• Acceptance criteria per SANS and utility standards.
• Commissioning reports and documentation.

Objectives:
• Develop a maintenance schedule for earthing systems.
• Identify common degradation mechanisms (corrosion, mechanical damage).
• Perform visual and electrical inspections.
• Record and rectify defects found during inspection.

Topics:
• Maintenance planning: frequency and scope.
• Corrosion types: galvanic, electrolytic, and environmental.
• Inspection of connections, conductors, and electrodes.
• Testing intervals and record keeping.
• Repair techniques: replacement, re-welding, adding electrodes.
• Safety during maintenance activities.

Objectives:
• Analyse earth fault scenarios in DC and AC systems.
• Explain operation of earth fault relays and protection schemes.
• Coordinate earthing with protection settings.
• Interpret fault records and recommend improvements.

Topics:
• Earth fault types: solid, resistive, and intermittent.
• Earth fault current paths and return circuits.
• Protection relays: directional, overcurrent, and sensitive earth fault.
• Setting coordination with earthing impedance.
• Fault recording and analysis tools.
• Case studies of earth fault incidents.

Objectives:
• Describe earthing for mixed DC/AC corridors.
• Evaluate use of earthing mats and gradient control wires.
• Understand impact of renewable integration on earthing.
• Discuss smart earthing monitoring systems.

Topics:
• Earthing in multi-system traction (DC+AC).
• Gradient control wires for step potential reduction.
• Earthing of solar/wind farms feeding traction.
• Remote monitoring of earth resistance and leakage.
• Use of conductive concrete and alternative electrodes.
• Regulatory updates and future trends.

Objectives:
• Demonstrate competence in bonding and earthing tasks.
• Complete a full earthing installation from design to test.
• Perform final inspection and generate compliance report.
• Pass written and practical assessments.

Topics:
• Practical exercise: design and install earthing for a simulated OHTE section.
• Conduct all tests: earth resistance, continuity, touch/step potential.
• Troubleshoot and rectify faults.
• Compile and present test report.
• Written assessment covering theory and standards.
• Feedback and certification guidance.