Earthing for Industrial Distribution Systems

Few topics generate as much controversy and argument as that of grounding (or earthing as it is called in some countries) and the associated topics of lightning and surge protection of electrical and electronic systems. Any engineer dealing with power supply networks needs to understand the basic principles of grounding system design and its role in ensuring safety of equipment and personnel.

A correct understanding of the basic principles involved will help him/her to avoid mistakes in grounding system design, mistakes that could lead to expensive failures and long downtime. In this workshop, we will demystify the concepts of grounding as applicable to utility networks and industrial plant distribution systems as well as their associated control equipment.

In fact, a lot of myths have been built around this subject, although it is quite a simple one when approached from basic principles. Our endeavour will therefore be to explain the fundamentals of grounding, which we hope will enable you to gain a correct perspective of the subject and give them the knowledge needed to solve real life grounding problems. Essentially this course is broken down into System Grounding, Protective grounding and Surge/noise protection of power and electronics systems normally found in distribution networks. A brief introduction to the design of substation grounding has been included. Detailed information on ground electrodes and measurement of ground resistance is also available.

Audience

This course is designed for:

Electrical supervisors
Electrical Engineers
Anyone involved in the earthing in industrial plants

Course objectives

This course objectives are to make an overview of the followings:

Basics of grounding
Bonding
Role of grounding in lightning protection
Ground electrodes and factors affecting their efficiency
Grounding issues in outdoor substations
Grounding for static charges
Surge Protection
Importance of grounding in mitigation of noise in sensitive circuits
Importance of Local Codes

Course contents

Day-1

POWER SUPPLY SYSTEM GROUNDING

Types of system grounding
Ungrounded systems
Solidly grounded systems
Impedance grounding using neutral reactor
Resonant grounding using neutral reactor
Impedance grounding through neutral resistance
Classification of supply systems based on grounding
Point of grounding
Other challenges

Day-2

PROTECTIVE GROUNDING

Electric shock, its cause and effects
Direct and indirect contact
Touch and step potential
Role of protective grounding in minimizing the shock hazards
Equipotential bonding
Protective grounding conductors and installation
Ground fault protection
System classification based on system/protective grounding

Day-3

PROTECTIVE GROUNDING

Electric shock, its cause and effects
Direct and indirect contact
Touch and step potential
Role of protective grounding in minimizing the shock hazards
Equipotential bonding
Protective grounding conductors and installation
Ground fault protection
System classification based on system/protective grounding

Day-4

GROUND ELECTRODE SYSTEMS

Soil resistance and factors affecting soil resistivity
Measurement of soil resistivity
Resistance of ground electrode and distribution of resistance in surrounding soil layers
Electrode current capacity
Ground electrode configurations
Parallel electrodes
Ground electrode resistance measurement
Chemical electrodes
Concrete encased electrodes and splicing methods
Corrosion of buried electrodes

Grounding practices
Basic design approach
Calculating the ground fault current
Ground potential rise in HV systems
Grounding design in LV and MV substations/installations
Grounding grid design for HV/EHV substations – A step-by-step approach
Introduction to 2-layer soil model
Transferred potential and ways of avoiding
Points needing special attention in substation grounding design and for GIS
equipment
Design of substations containing converter equipment feeding to HVDC transmission systems
Ensuring effective substation grounding – Important aspects

grounding system maintenance

Day-5

STATIC ELECTRICITY AND PROTECTION

What is static electricity and how is it generated?
Examples of static charge build up and its dangers
Energy of spark due to static electricity
Ways of controlling static build up
Risk assessment and preventive measures

GROUNDING FOR LIGHTNING PROTECTION OF BUILDINGS AND STRUCTURES

The physics of lightning
Lightning incidence in different land masses
Lightning strike probability
Lightning protection
Planning for protection and decision factors
Improved approach to lightning protection and non-conventional systems
Effect of lightning strikes on electrical installations

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