Question

List different types of faults occured on a power system. Draw necessary sketches (any four)

Answer 1

In a power system, faults are abnormal conditions that can disrupt the normal operation of the electrical network. These faults can be categorized based on their nature and the part of the system they affect. Here are some common types of faults in a power system, along with their descriptions and typical sketches:

### 1. **Single Line-to-Ground Fault (SLG)**

**Description:**
A Single Line-to-Ground Fault occurs when one phase of the power system comes into contact with the ground. This type of fault is the most common in power systems and is often caused by insulation failure or equipment malfunction.

**Sketch:**

```
  Phase A      Phase B      Phase C
    |            |            |
   ___          ___          ___
    |            |            |
   ----          ----        ----
    |            |            |
   ---           ---          ---
    |            |            |
   ---          ---          ---
    |            |            |
   \|/          \|/          \|/
   Ground       Ground       Ground
```

### 2. **Line-to-Line Fault (LL)**

**Description:**
A Line-to-Line Fault occurs when two phases of the power system come into contact with each other. This can happen due to equipment failure or short circuits. It results in a short circuit between the two phases, creating an abnormal condition in the system.

**Sketch:**

```
  Phase A      Phase B      Phase C
    |            |            |
   ___          ___          ___
    |            |            |
   ----          ----        ----
    |            |            |
   ----          ----        ----
    |            |            |
   \|/          \|/          \|/
   (Short)      (Short)      (Ground)
```

### 3. **Double Line-to-Ground Fault (DLG)**

**Description:**
A Double Line-to-Ground Fault involves two phases coming into contact with the ground. This type of fault can be more severe because it affects multiple phases and can lead to a significant disruption in the system.

**Sketch:**

```
  Phase A      Phase B      Phase C
    |            |            |
   ___          ___          ___
    |            |            |
   ----          ----        ----
    |            |            |
   ---          ---          ---
    |            |            |
   \|/          \|/          \|/
   Ground       Ground       Ground
```

### 4. **Three-Phase Fault (3Φ)**

**Description:**
A Three-Phase Fault occurs when all three phases come into contact with each other. This type of fault is less common but is typically the most severe, resulting in a high fault current and significant damage.

**Sketch:**

```
  Phase A      Phase B      Phase C
    |            |            |
   ___          ___          ___
    |            |            |
   ----          ----        ----
    |            |            |
   ----          ----        ----
    |            |            |
   \|/          \|/          \|/
   (Short)      (Short)      (Short)
```

### Summary

- **Single Line-to-Ground Fault (SLG):** One phase to ground.
- **Line-to-Line Fault (LL):** Two phases to each other.
- **Double Line-to-Ground Fault (DLG):** Two phases to ground.
- **Three-Phase Fault (3Φ):** All three phases to each other.

Each fault type requires different protection and mitigation strategies to ensure the stability and safety of the power system.

Answer 2

In power systems, various types of faults can occur, each with its own characteristics and impact on the system. Here are four common types of faults, along with brief descriptions and sketches to illustrate each type:

### 1. **Single Line-to-Ground Fault (SLG)**

**Description:**
- Occurs when one phase comes into contact with the ground or earth.
- This type of fault is often caused by insulation failure or equipment damage.
- It can cause high currents to flow through the ground and affect the stability of the power system.

**Sketch:**

```
     ----
   |     |
   |     |
   |     |      G
   |     |----|
   |     |    |
     ----      |
               |
              ---
              | |
              | |  Earth/Ground
              ---
```

### 2. **Line-to-Line Fault (LL)**

**Description:**
- Happens when two phases come into contact with each other.
- This type of fault is usually caused by equipment failure or short circuits.
- It results in a short circuit between the two phases, causing large fault currents.

**Sketch:**

```
   ----       ----
 |     |     |     |
 |     |-----|     |
 |     |     |     |
   ----       ----
```

### 3. **Double Line-to-Ground Fault (DLG)**

**Description:**
- Occurs when two phases come into contact with the ground.
- It can be caused by insulation breakdown or conductor failure.
- This type of fault is severe and often results in large fault currents and system instability.

**Sketch:**

```
     ----      ----
   |     |    |     |      G
   |     |----|     |----|
   |     |    |     |    |
     ----      ----   ---
                      | |
                      | |  Earth/Ground
                      ---
```

### 4. **Three-Phase Fault (3P)**

**Description:**
- Involves all three phases coming into contact with each other or a common point.
- This is the most severe type of fault and usually occurs due to severe equipment failure or system disturbances.
- It results in very high fault currents and can cause significant damage to the system.

**Sketch:**

```
   ----
 |     |
 |     |
 |     |
   ----
   |   |
   |   |
   |   |
   ----
```

These sketches are simplified and meant to give a basic idea of how each fault occurs in a power system. For detailed analysis and protection system design, more sophisticated diagrams and calculations are used.