Extra High Tension Underground Cable Voltage Rating

Underground cables are classified based on their operating voltage levels. These classifications help determine the type of insulation and construction required for safe and efficient power transmission.

The common classifications for underground cables based on voltage are:

• Low Tension (LT) Cables: Up to 1 \(\text{kV}\)
• High Tension (HT) Cables: From 1 \(\text{kV}\) up to 11 \(\text{kV}\)
• Super Tension (ST) Cables: From 22 \(\text{kV}\) up to 33 \(\text{kV}\)
• Extra High Tension (EHT) Cables: From 33 \(\text{kV}\) up to 66 \(\text{kV}\)
• Extra Super Voltage Cables: Above 132 \(\text{kV}\)

Based on this classification, extra high tension (EHT) underground cables are designed to operate within a specific voltage range.

Looking at the options provided and the standard classification, the voltage rating for extra high tension underground cables is typically from 33 \(\text{kV}\) to 66 \(\text{kV}\).

Let's check the options:

• 33 \(\text{kV}\) to 66 \(\text{kV}\): This range matches the definition of Extra High Tension (EHT) cables.
• 22 \(\text{kV}\) to 33 \(\text{kV}\): This range is typically classified as Super Tension (ST).
• 11 \(\text{kV}\): This falls under High Tension (HT).
• 132 \(\text{kV}\): This falls under Extra Super Voltage.

Therefore, the correct voltage rating for extra high tension underground cables is 33 \(\text{kV}\) to 66 \(\text{kV}\).