Determining if a photovoltaic DC cable is aging requires a comprehensive assessment of its insulation performance, mechanical strength, and operational stability, combining visual inspection, electrical performance testing, environmental factor analysis, and professional testing methods.
1. Visual Inspection
Observe the cable surface condition visually or with magnifying tools:
Discoloration or Embrittlement: Normal insulation has a uniform color (e.g., black, gray). Yellowing, whitening, or loss of elasticity indicate material aging.
Cracks or Delamination: Focus on checking for cracks and sheath peeling at bends and joints, especially after prolonged exposure to sun and rain.
Bulging or Deformation: Localized expansion may be due to internal moisture or thermal aging causing volume expansion.
Mechanical Damage: Check for indentations, scratches, or animal bite marks. Exposed conductors increase the risk of short circuits.
2. Electrical Performance Testing
Insulation Resistance Test
Use a megohmmeter (e.g., 500V/1000V range) to measure the insulation resistance between the conductor and ground.
The insulation resistance of new cables should be ≥100 MΩ·km. If it is below 1 MΩ, it indicates severe insulation aging and requires immediate replacement.
Data should be recorded regularly. If the annual average decrease exceeds 20%, it indicates accelerated aging.
