Question

Describe with neat sketch any one type of earthing system.

Answer 1

An earthing system, also known as grounding, is crucial for electrical safety and system stability. One common type of earthing system is the **TT system**. Here's a detailed description along with a sketch.

### TT Earthing System

**Description:**
The TT (Terra-Terra) earthing system is characterized by the use of separate earthing electrodes for the electrical installation and the utility supply. In this system:

- **Earth Electrode:** The installation has its own earthing electrode, which is connected to the earth. This electrode is typically a metal rod, plate, or grid buried in the ground.
- **Neutral Connection:** The neutral point of the supply transformer is earthed. This ensures that the supply system and the installation have a common reference point.
- **Separation:** The earthing system of the utility is separate from the earthing system of the installation, hence the term "TT".

**Advantages:**
1. **Safety:** It provides an additional layer of safety as faults in the installation do not affect the utility earthing.
2. **Low Resistance Path:** The earth electrode provides a low-resistance path for fault currents, ensuring that protective devices (like circuit breakers) operate quickly to disconnect faulty circuits.
3. **Prevention of Voltage Rise:** It helps prevent dangerous voltage rises on the installation during earth faults.

**Disadvantages:**
1. **Dependence on Local Soil Conditions:** The effectiveness of the TT system can vary with soil resistivity.
2. **Potential for High Touch Voltages:** In certain fault conditions, touch voltages can be higher than acceptable levels.

### Neat Sketch

Here’s a simple sketch to illustrate the TT earthing system:

```
                         [ Supply Transformer ]
                                 |      
                                 |          
                              Neutral
                                 |
                          ------------
                          |          |
                          |          |
                          |          |
                      [ Earthing   [ Installation ]
                        Electrode      |
                          (Earth)     [ Equipment ]
                                     [ Earthed ]
```

### Key Components:
1. **Supply Transformer**: Provides electrical supply.
2. **Neutral Connection**: Connected to ground for safety.
3. **Earthing Electrode**: A metal rod or plate buried in the ground.
4. **Installation**: The electrical installation (e.g., a building) with its own earthing system.

### Conclusion
The TT earthing system is widely used in residential and commercial buildings, providing effective grounding while ensuring safety and reliability in electrical installations. Proper installation and maintenance of the earthing system are essential to maximize safety benefits.

If you have any questions or need further details about different types of earthing systems, feel free to ask!

Answer 2

Here is a neat sketch of the TT earthing system. It illustrates the connection between the power source, electrical installation, and earth electrodes. The system shows how the neutral is connected to the ground and how the electrical load has its own separate earth connection.