What is Electrical Earthing: Types of Electrical Earthing and Type of Earthing System?

 

Electrical Earthing

The path of transferring the discharge of electrical current directly to the ground with the help of low resistance wire is known as the electrical earthing. The electrical earthing has been designed by linking the non-current carrying part of the equipment or neutral of the system to the ground. In Bangladesh, HDBC (Hard Drawn Bare Copper) is used for the earthing conductor. Moreover it provides the shortest path to the leakage current. The short circuit current of the equipment or system passes to the earth which has zero potential. Thus, protects the system and equipment from damage.

Types of Electrical Earthing

Electrical system earthing can be classified into two types.

1. Neutral Earthing
2. Equipment Earthing

Neutral/System Earthing

In neutral earthing, the neutral of the system is straight connected to earth by GI wire/HDBC. The neutral earthing is also called the system earthing. Such type of earthing is mostly provided to the system which has star winding. For example, the neutral earthing is provided in the generator, transformer, motor etc.

Equipment Earthing

Such type of earthing is provided to the electrical equipment. The non-current carrying part of the equipment like their metallic frame is connected to the earth by the help of the conducting wire. If any fault occurs in the apparatus, the short-circuit current to pass the earth by the help of wire. Thus, protect the system from damage.

Importance of Earthing

The earthing is crucial because of the following motives:

1.   To protect engineers/technicians/general people from electric shock.

2.   To protect the apparatus of the system.

3.   A good low resistance electrical path ensure that, the electrical faults will clear quickly without harming any equipment’s.

4.   The earthing protects the personnel from the shortcircuit current.

5.   The earthing provides the easiest path to the flow of shortcircuit current even after the failure of the insulation.

6.   Earthing is mandatory to work properly for SPDs.

7.   In some electronic devices, earthing can reduce the hamming or electrical noise. 

Different Type of Earthing System

Different types of earthing systems are available. Popular methods are:

• Plate Earthing: A copper plate or galvanized plate is buried in an earth pit below ground level. The plate electrode connects the electrical conductors to the earth.
• Pipe Earthing: A galvanized steel perforated pipe inside the ground connects the electrical conductors to the earth.
• Rod Earthing: Similar to the Pipe earthing. A copper rod replaces the pipe electrode.
• Chemical earthing: Similar to the pipe earthing. A chemical compound material replaces the charcoal and salt layers.