Electrical Earthing means connecting non-current-carrying parts of electrical equipment or the supply system’s neutral point to the earth so that electrical energy can be discharged immediately and safely. Earthing is accomplished by connecting installation parts to electrical conductors or electrodes buried in the soil. This contacting arrangement is known as the earthing. In this article, the term earthing refers to electrical earthing.
Earthing connections refer to the metallic conductors that connect the installation’s components to the earthing.
It is standard practice to use the term earthing system when discussing the earthing and earthing connections together as a whole.
By earthing the equipment, a simple path is provided to the leakage or short-circuit current. In the event of a short-circuit, the short-circuit current passes to the earth, which has a zero potential. In this way, the system and equipment are protected from damage.
What are the objectives of earthing?
The following objectives are achieved by earthing.
1. In the event of a short circuit, the earthing would protect the personnel from being electrocuted.
2. Even if there is a failure of the insulation, the earthing will continue to provide the best way for short-circuit current to flow through.
3. During high-voltage surges and lightning discharges, the earthing system protects the apparatus and personnel.
4. For providing a method of effectively discharging and de-energizing feeders or equipment prior to performing maintenance on them.
Types of Earthing
Electrical equipment generally consists of two parts that do not carry current. The neutral of the supply system and the frame of the electrical equipment are the two parts that do not carry current under normal situations. Two types of earthing can be distinguished based on the earthing of these two non-currents-carrying components of the electrical system.
- Neutral Earthing
- Equipment Earthing
1. Neutral Earthing
As part of neutral earthing, the neutral of the system is directly connected to the earth through the use of connecting wires.
In other words, neutral earthing ensures system security and protection by earthing the system’s neutral. Neutral earthing is also known as system earthing or grounding. An earthing system of this type is usually used with systems that have star windings. In the case of generators, transformers, motors, etc., neutral earthing is provided.
2. Equipment Earthing
Electrical equipment is provided with this type of earthing. With the aid of the conducting wire, the non-current-carrying parts of the equipment are connected to the earth. In case of a fault in equipment, short-circuit current is passed to the earth through a wire. In this way, the system is protected from damage and ensures personnel safety. Equipment earthing is also known as safety earthing.
The earthing of equipment also contributes to earth fault protection. In the case of earth faults, the earth fault current flows to the earth through the earthing system. The faulty current is detected by the protection system. Hence protection system opens the circuit breakers to prevent damage. The faulty electrical equipment is then repaired and reinstalled. During fault current flow, the earthed components maintain a potential close to that of the earth.
Advantages of earthing
The advantages of earthing are as follows.
1. The safety of electrical appliances and devices is ensured by protecting them from excessive electric currents.
2. Ensures that the electric appliance is protected from damage.
3. Buildings are protected from lightning damage.
4. The earthing of electrical equipment prevents injuries and death caused by electric currents.
5. Fires can be prevented in electrical installation systems by earthing.