How are overhead transmission lines classified?
2 Answers
Overhead transmission lines are typically classified based on several criteria, including:
1. **Voltage Level**:
- **Low Voltage**: Generally up to 1 kV.
- **Medium Voltage**: From 1 kV to 35 kV.
- **High Voltage**: From 35 kV to 230 kV.
- **Extra High Voltage (EHV)**: Above 230 kV, typically up to 800 kV or more.
2. **Construction Type**:
- **Single Circuit**: A line that has one circuit for power transmission.
- **Double Circuit**: A line that has two circuits on the same set of structures, allowing for greater capacity and redundancy.
3. **Conductor Configuration**:
- **Bundled Conductors**: Multiple conductors per phase, often used for high voltage to reduce corona discharge and line losses.
- **Single Conductor**: One conductor per phase.
4. **Type of Conductor Material**:
- **Aluminum**: Common due to its lightweight and conductivity.
- **Copper**: Less common for large transmission lines due to weight and cost but used in some applications.
5. **Usage**:
- **Transmission Lines**: For transferring high voltage electricity over long distances.
- **Distribution Lines**: For distributing lower voltage electricity to consumers.
6. **Insulation Type**:
- **Bare Conductors**: Directly exposed to the environment.
- **Insulated Conductors**: Covered with insulating materials, used in certain applications to prevent electrical faults.
These classifications help in designing, maintaining, and managing overhead transmission systems effectively.
1. **Voltage Level**:
- **Low Voltage**: Generally up to 1 kV.
- **Medium Voltage**: From 1 kV to 35 kV.
- **High Voltage**: From 35 kV to 230 kV.
- **Extra High Voltage (EHV)**: Above 230 kV, typically up to 800 kV or more.
2. **Construction Type**:
- **Single Circuit**: A line that has one circuit for power transmission.
- **Double Circuit**: A line that has two circuits on the same set of structures, allowing for greater capacity and redundancy.
3. **Conductor Configuration**:
- **Bundled Conductors**: Multiple conductors per phase, often used for high voltage to reduce corona discharge and line losses.
- **Single Conductor**: One conductor per phase.
4. **Type of Conductor Material**:
- **Aluminum**: Common due to its lightweight and conductivity.
- **Copper**: Less common for large transmission lines due to weight and cost but used in some applications.
5. **Usage**:
- **Transmission Lines**: For transferring high voltage electricity over long distances.
- **Distribution Lines**: For distributing lower voltage electricity to consumers.
6. **Insulation Type**:
- **Bare Conductors**: Directly exposed to the environment.
- **Insulated Conductors**: Covered with insulating materials, used in certain applications to prevent electrical faults.
These classifications help in designing, maintaining, and managing overhead transmission systems effectively.
Overhead transmission lines, which are used to transmit electrical power over long distances, are classified based on various factors including their voltage level, construction, and usage. Here's a detailed breakdown of these classifications:
### 1. **Voltage Classification**
- **Low Voltage (LV) Lines**: These typically carry voltages up to 1 kV (1000 volts). They are used for local distribution in residential and commercial areas.
- **Medium Voltage (MV) Lines**: These lines operate at voltages between 1 kV and 35 kV. They are used for distribution from substations to local areas.
- **High Voltage (HV) Lines**: These carry voltages between 35 kV and 230 kV. They are used for regional transmission and to connect substations.
- **Extra High Voltage (EHV) Lines**: These operate at voltages between 230 kV and 765 kV. They are used for long-distance transmission across larger regions or even countries.
- **Ultra High Voltage (UHV) Lines**: These lines operate at voltages above 765 kV. They are used for extremely long-distance transmission, often spanning continents.
### 2. **Construction and Design Classification**
- **Single-Circuit Lines**: These lines have one set of conductors per phase. They are typically used for lower voltage transmissions and are simpler in design.
- **Double-Circuit Lines**: These lines have two sets of conductors per phase, which can increase the transmission capacity and provide redundancy in case of a fault.
- **Triple-Circuit Lines**: These are less common but can have three sets of conductors per phase. They are used in high-demand areas to maximize capacity.
### 3. **Construction Type**
- **Wooden Poles**: Historically, wooden poles were commonly used for lower voltage lines. They are still used in some rural and less developed areas.
- **Steel Poles**: Steel poles are used for higher voltage lines due to their strength and durability. They can be either tubular or lattice structures.
- **Concrete Poles**: Concrete poles are used for medium to high voltage lines. They are durable and resistant to weather but can be heavier and more difficult to install.
### 4. **Usage Classification**
- **Transmission Lines**: These are designed to transport electrical power over long distances from power plants to substations.
- **Distribution Lines**: These lines carry electricity from substations to end-users, including residential, commercial, and industrial consumers.
- **Subtransmission Lines**: These serve as a bridge between high-voltage transmission lines and local distribution networks.
### 5. **Insulation and Safety**
- **Bare Wires**: Some overhead lines use bare conductors, which are typically used for lower voltages and where the risk of contact is minimal.
- **Insulated Wires**: For higher voltages and safety concerns, conductors may be insulated to prevent accidental contact and to minimize electrical losses.
Each type of classification has specific applications and advantages depending on factors such as distance, capacity, and environmental conditions. Understanding these classifications helps in designing and maintaining efficient and reliable power transmission systems.
### 1. **Voltage Classification**
- **Low Voltage (LV) Lines**: These typically carry voltages up to 1 kV (1000 volts). They are used for local distribution in residential and commercial areas.
- **Medium Voltage (MV) Lines**: These lines operate at voltages between 1 kV and 35 kV. They are used for distribution from substations to local areas.
- **High Voltage (HV) Lines**: These carry voltages between 35 kV and 230 kV. They are used for regional transmission and to connect substations.
- **Extra High Voltage (EHV) Lines**: These operate at voltages between 230 kV and 765 kV. They are used for long-distance transmission across larger regions or even countries.
- **Ultra High Voltage (UHV) Lines**: These lines operate at voltages above 765 kV. They are used for extremely long-distance transmission, often spanning continents.
### 2. **Construction and Design Classification**
- **Single-Circuit Lines**: These lines have one set of conductors per phase. They are typically used for lower voltage transmissions and are simpler in design.
- **Double-Circuit Lines**: These lines have two sets of conductors per phase, which can increase the transmission capacity and provide redundancy in case of a fault.
- **Triple-Circuit Lines**: These are less common but can have three sets of conductors per phase. They are used in high-demand areas to maximize capacity.
### 3. **Construction Type**
- **Wooden Poles**: Historically, wooden poles were commonly used for lower voltage lines. They are still used in some rural and less developed areas.
- **Steel Poles**: Steel poles are used for higher voltage lines due to their strength and durability. They can be either tubular or lattice structures.
- **Concrete Poles**: Concrete poles are used for medium to high voltage lines. They are durable and resistant to weather but can be heavier and more difficult to install.
### 4. **Usage Classification**
- **Transmission Lines**: These are designed to transport electrical power over long distances from power plants to substations.
- **Distribution Lines**: These lines carry electricity from substations to end-users, including residential, commercial, and industrial consumers.
- **Subtransmission Lines**: These serve as a bridge between high-voltage transmission lines and local distribution networks.
### 5. **Insulation and Safety**
- **Bare Wires**: Some overhead lines use bare conductors, which are typically used for lower voltages and where the risk of contact is minimal.
- **Insulated Wires**: For higher voltages and safety concerns, conductors may be insulated to prevent accidental contact and to minimize electrical losses.
Each type of classification has specific applications and advantages depending on factors such as distance, capacity, and environmental conditions. Understanding these classifications helps in designing and maintaining efficient and reliable power transmission systems.