Answer: The testing and commissioning phase is a crucial step to ensure the long-term reliability of an EHV cable system. This process typically involves a series of rigorous tests:

• Pre-Installation Checks: Verifying the cable's integrity before it is pulled, ensuring there is no damage from transportation or handling.

• Insulation Resistance Test: Using a megger to check the insulation resistance of the cable.

• Partial Discharge (PD) Test: This is a vital test for EHV cables. It detects any minute electrical discharges that could indicate a flaw in the insulation or jointing, which could lead to future failure.

• High Voltage AC/DC Withstand Test: Applying a high voltage to the cable for a specified duration to prove its ability to withstand operational voltage without breakdown.