The exact number of insulators in a 132 kV line isn’t fixed—it depends on the design criteria, environmental conditions, and the type of insulator used.
Table of Contents
Insulator String Configuration
For a 132 kV overhead line, each phase is usually supported by a suspension insulator string. In many designs, this string often consists of about 7 insulator discs. This number is chosen to provide the required electrical insulation (clearance and creepage distance) and mechanical strength.
Design Considerations
Electrical Requirements: The insulator string must handle the line’s voltage and prevent leakage currents or arcing.
Mechanical Strength: It should support the weight of the conductor and withstand environmental stresses such as wind or ice loads.
Environmental Conditions: In areas with heavy pollution or extreme weather, designers might adjust the number or type of insulators to ensure reliable performance.
How many insulators per kV?
Standard Insulator Disc Calculation
- Typically, 1 insulator disc is rated for around 11-15 kV.
- The number of insulators required for a given voltage is calculated
Common Voltage Levels & Insulator Disc Count
| Line Voltage | Typical Number of Insulator Discs |
|---|---|
| 11 kV | 1 – 2 discs |
| 33 kV | 3 – 4 discs |
| 66 kV | 5 – 6 discs |
| 132 kV | 7 – 9 discs |
| 220 kV | 10 – 14 discs |
| 400 kV | 16 – 23 discs |
| 765 kV | 30 – 40+ discs |
Which conductors are used in 132kV transmission line?
In a 132 kV transmission line, the conductors used must have high conductivity, mechanical strength, and corrosion resistance. The most commonly used conductors are:
1. ACSR (Aluminum Conductor Steel Reinforced)
Most common choice for 132 kV lines.
Construction: Aluminum strands wrapped around a central steel core.
Advantages:High tensile strength,Good conductivity,Cost-effective and widely available.
Common ACSR types for 132 kV lines:
ACSR Panther (conductor size: 30/3 mm)
ACSR Zebra (conductor size: 54/7 mm)
ACSR Moose (conductor size: 54/7 mm, used for higher current capacity).
2. AAAC (All Aluminum Alloy Conductor)
Made entirely of aluminum alloy,Higher corrosion resistance than ACSR,Lighter weight and more flexible,Used in coastal or high-pollution areas.
3. ACCC (Aluminum Conductor Composite Core)
Uses a composite core instead of steel,Lighter, stronger, and more efficient than ACSR,Used in projects requiring reduced sag and increased capacity.
4. ACSS (Aluminum Conductor Steel Supported)
Similar to ACSR but with fully annealed aluminum strands,Handles higher temperatures without sagging,Used for heavy-loaded transmission lines.
Selection Criteria for 132 kV Conductors
Current Carrying Capacity: Depends on the load demand.
Mechanical Strength: To withstand wind, ice, and tension.
Line Length & Sag Considerations: To minimize losses and maintain ground clearance.
Environmental Conditions: Coastal, industrial, or high-temperature areas may require corrosion-resistant materials.
For 132 kV transmission lines, ACSR (Panther, Zebra, or Moose) is the most widely used conductor due to its balance of strength, conductivity, and cost-effectiveness.
