Intersheath Grading


Intersheath Grading is a method of ensuring that the voltage gradient across the insulation of a cable does not become so steep as to cause the failure of the insulation.  The insulation of a cable is subjected to constant electrostatic stress.  This electrical stress is dependent on the voltage of the conductor.  The electrostatic stress needs to be uniform across the insulation.  Uneven electrostatic stresses can result in failure of the insulation. 

Intersheath Grading is a method of creating uniform voltage gradient across the insulation by means of separating the insulation into two or more layers by thin conductive strips.  These strips are kept at different voltage levels through the secondary of a transformer.  This ensures that all parts of the insulation are exposed to relatively the same stress.  

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