Over 70% of underground cable circuit breakdowns occur at joints and terminations. Understanding non-linear stress relief and correct preparation geometry is vital for long-term cable network reliability.
The Physics of Cable Stress at Cut Ends
When an extruded XLPE or EPR power cable is cut to create a termination, the semi-conductive screen abruptly terminates. This creates an intense concentration of electrical field lines at the edge of the shield cut, easily exceeding the breakdown strength of air (3 kV/mm) and resulting in destructive surface tracking.
Engineered systems like Raychem RPG heat-shrinkable EPKT and cold-shrinkable CST terminations integrate specially formulated stress control materials with non-linear voltage-current characteristics (high dielectric permittivity). This material refracts and smooths the longitudinal electric field along the entire creepage distance.
Heat Shrink vs Cold Shrink: Making the Selection
While heat shrink terminations provide rugged mechanical protection, superior UV resistance, and excellent versatility across conductor shapes, cold shrink sleeves offer flame-free installation inside hazardous zones (substations, underground metro tunnels, and chemical plants). Synergy supplies the full authorized spectrum of Raychem RPG joints, terminations, and separable connectors up to 66kV.
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