Grounding, also known as earthing, is a fundamental concept in electrical engineering and safety that involves connecting electrical equipment or systems to the Earth or a conductive body to provide a safe path for the dissipation of electrical faults, static charges, and lightning strikes. The primary purposes of grounding are to:

1. Ensure safety by providing a low-resistance path to Earth for fault currents, which helps prevent electric shock hazards to personnel and damage to equipment.
2. Stabilize voltage levels and minimize electromagnetic interference by providing a reference point for electrical systems.

Grounding can be achieved through various means, including grounding electrodes (such as ground rods or plates), grounding conductors (such as bare copper wires or metal pipes), and grounding systems (such as grounding grids or grounding mats).

Difference between Grounded and Ungrounded Systems:

1. Grounded Systems:

   • In a grounded electrical system, one or more conductors (usually the neutral conductor) are intentionally connected to the Earth or a grounding electrode. This connection provides a reference point for the system voltage and allows fault currents to flow safely to Earth.
   • Grounded systems can be further classified into solidly grounded systems, where the neutral conductor is directly connected to the Earth, and impedance grounded systems, where a resistor or reactor is used to limit fault currents.
   • Advantages of grounded systems include improved safety by providing a low-impedance fault path, reduced risk of equipment damage from lightning strikes and transient overvoltages, and improved reliability by stabilizing system voltage levels.
   • Disadvantages of grounded systems include the potential for ground faults to develop into phase-to-phase faults (which can lead to system outages), increased complexity due to the need for ground fault protection devices, and the risk of ground potential rise during fault conditions.

2. Ungrounded Systems:

   • In an ungrounded electrical system, none of the conductors are intentionally connected to the Earth or grounding electrodes. The system floats with respect to Earth ground.
   • Ungrounded systems are primarily used in critical applications where uninterrupted power supply is essential, such as in hospitals, data centers, and industrial processes.
   • Advantages of ungrounded systems include the ability to continue operating with a single-phase fault without causing a system-wide outage, improved reliability by avoiding the need for ground fault protection devices, and reduced risk of ground potential rise during fault conditions.
   • Disadvantages of ungrounded systems include increased risk of electric shock hazards due to the absence of a low-impedance fault path, difficulty in locating and repairing ground faults, and potential for transient overvoltages to cause insulation breakdown and equipment damage.

In summary, the main difference between grounded and ungrounded systems lies in the presence or absence of intentional connections to the Earth or grounding electrodes. Grounded systems provide a low-impedance fault path to Earth for improved safety and stability, while ungrounded systems offer certain advantages in terms of reliability and uninterrupted operation but require careful consideration of potential risks and safety measures.