
In this lecture you will learn.
System Failures on industrial power system
What is ground faults?
Types of faults
Ungrounded System
Ground Faults
Arching ground faults
Bolted ground faults
In this lecture you will learn
Arching ground faults
Hazards with grounded
Resistance grounding
In this lecture you will learn
Separate Grounding Resistors
Benefits of Grounding
Identify major causes of industrial power system failures, showing line-to-ground faults at about 98% and earth faults at about 90%, and emphasize earthing to isolate healthy from faulty parts.
Understand how a ground fault occurs in a star-connected system when an overloaded conductor contacts earth, causing near-zero impedance and massive fault current that threatens equipment and touch voltage.
Identify and contrast voltage faults and arc faults in power systems, including bolted faults and media in arcing, highlighting the extreme energy and damage of arc faults.
Analyze ground fault distribution in a delta system, the circulating current, and how high frequency oscillations and loop impedance influence earth fault protection.
Analyze bolted ground faults in a solidly grounded star system and show fault current distribution back to the neutral using full-load current and impedance, including ECB and ICC.
Compare ungrounded and solidly grounded systems to reveal hazards, noting that ungrounded setups face large transient overvoltages that threaten insulation and personnel, while solidly grounded systems enable fast fault isolation.
Understand low and high resistance grounding in earthing design: low resistance limits fault current and arc hazards, while high resistance maintains service after faults, with considerations for ratings and ventilation.
Explain elevated voltage hazards in a high-resistance grounded, star-configured system, and show how properly rated equipment, ground-fault relays, and sensing resistors protect against arc and short-circuit faults.
Explore solidly grounded systems for three-phase four-wire networks, including resistance, hybrid, and separate grounding to control fault current, capacitive charging, and parallel generator coordination.
Explore earthing layout concepts for electrical plants, including underground earth grids, pit locations, redundancy, and how lightning protection, neutral earthing, and equipment earthing are laid out and connected.
Identify how S1-S4 sources map to D1-D3 damages and L1-L4 losses, covering direct and indirect lightning and line-related effects, for building risk assessment.
Analyze a typical diagram of an external lightning protection system showing terminal system, catenary wire, mast, three conductors, clamps, splicer joints, insulation supports, and earth pits.
What is Earthing or Grounding?
A safety measure devised to prevent people from getting shocked if the insulation inside electrical devices fails is called Earthing. To answer our initial question, the third pin in the plug is actually the “Earth” or “Ground” connection of the electrical appliance.
The Earth, being a good conductor of electricity, acts as a convenient path for the flow of electrons that escape the insulation. Furthermore, the gigantic size of the Earth paves a path for the safe discharge of the electric charge.
In technical terms, Electrical Earthing can be defined as the process of transferring the immediate discharge of the electrical energy directly to the Earth with the help of the low-resistance wire. The electrical earthing is carried out by connecting the non-current-carrying part of the equipment or the neutral part of the supply system to the ground.
As stated earlier, earthing provides a simple path for the leakage current i.e., the current that escapes from a device if there’s any fault in the insulation. The short circuit current (current that follows the path of least resistance) of the equipment passes to the Earth, which has zero potential, thus protecting the system and equipment from damage.
Why is earthing necessary?
Human Safety
Safety of Electrical Equipment
Protection of Buildings from Lightning
Types of Earthing methods
Plate earthing
Pipe earthing
Rod earthing
Water main method
What is a lightning protection system?
Lightning protection systems are used to prevent or lessen lightning strike damage to buildings. They protect the internal electrical components of a building, helping to prevent fires or electrocution. Lightning protection comes in the form of a lightning conductor, usually a metal rod, mounted on a building to protect it from lightning strikes. The system will intercept a strike so if lightning hits the building, the lightning rod will be hit first, causing the strike to be conducted through a wire, and passing through to the ground safely.
In a lightning protection system, the lightning rod is a single component of the system. The lightning rod requires a connection to earth to give a building protection. Lightning rods come in many different forms, including hollow, solid, pointed or rounded. All lightning rods are made of conductive materials, such as copper and aluminum.
Because of the high energy and current levels associated with lightning a lightning protection system can never guarantee complete safety from the effects of lightning. In a lightning protection system, the current will divide to follow every conductive path to ground but even the divided current can cause damage. These secondary “side-flashes” can still cause a fire, blow apart brick, stone, or concrete, or injure anyone within a building.