1. Based on Voltage Levels:
- Ultra High Voltage (UHV): Above 765 kV, used for super long-distance transmission and are used in countries with extensive power grids.
- Extra High Voltage (EHV): 220 kV to 765kV, used for long-distance, bulk power transmission.
- High Voltage (HV): 110 kV to 220 kV, used for regional transmission.
- Medium Voltage (MV): 33 kV to 110 kV, used for sub transmission and linking major substations.
- Low Voltage (LV): Below 33 kV, primarily used for local distribution to end-users.
2. Based on Current Type:
- Alternating Current (AC) Transmission Lines: The most common type, used for both short and long distances. Examples include 66 kV, 132 kV, and 230 kV lines.
- Direct Current (DC) Transmission Lines: Used for very long distances and underwater cables due to lower energy losses. Examples include High Voltage Direct Current (HVDC) lines operating at 100kV, 500 kV, 800 kV, or higher.
3. Based on Configuration:
- Overhead Transmission Lines: Conductors are suspended by towers or poles. This is the most common configuration for high and extra high voltage transmission.
- Underground Transmission Lines: Conductors are buried underground, used in urban areas or where overhead lines are impractical.
4. Based on Length:
Short Transmission Lines:
- Length: Up to 80 km.
- Characteristics: Low voltage drop, less capacitance effect.
- Typical Use: Interconnecting nearby substations or serving local areas.
Medium Transmission Lines:
- Length: 80 km to 250 km
- Characteristics: Moderate voltage drop, noticeable capacitance and inductance effects.
- Typical Use: Regional power distribution and connecting substations within a region.
Long Transmission Lines:
- Length: Above 250 km
- Characteristics: Significant voltage drop, high capacitance and inductance effects, often require reactive power compensation.
- Typical Use: Long-distance power transmission, interconnecting distant power plants and large load centers.
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