A failure in the insulation material of a cable, allowing uncontrolled electrical current to pass between conductors or to the ground.
How it happens:
Insulation breakdown can be caused by various factors:
- Prolonged electrical stress, leading to overheating and material degradation.
- Mechanical damage, such as cuts or compression during installation or maintenance.
- Environmental influences, including moisture penetration, chemical exposure, or surface contamination.
- Aging effects, where insulation deteriorates over time due to wear and material fatigue.
Types of breakdown:
- Complete breakdown – The insulation is fully compromised, allowing direct current flow between conductors.
- High-resistance breakdown – The fault maintains high resistance but still causes leakage currents.
- Intermittent breakdown – Occurs under specific conditions, such as temperature changes or humidity fluctuations.
Detection methods:
Technicians use various diagnostic tools to identify insulation breakdown, including:
- Time-Domain Reflectometry (TDR) – Detects impedance changes and estimates fault distance.
- Surge Generator (Thumper) – Applies high-voltage pulses to create an arc at the fault location for acoustic or visual detection.
- Insulation Resistance Testing (Megohmmeter) – Measures the overall condition of the insulation layer.
- Thermal Imaging – Identifies overheating zones linked to insulation failure.
Why it’s dangerous:
Insulation breakdown can lead to cable overheating, short circuits, system failures, and even fire hazards.
Prevention methods:
- Using high-quality insulation materials resistant to heat and mechanical stress.
- Regular testing and preventive maintenance, especially in high-load environments.
- Protecting cable routes from moisture and physical damage.
