The purpose of condition monitoring is to reveal the actual health of the high-voltage cables.

 

All high voltage cables have different condition and are exposed to various stresses which will affect the life of the cable. For the same reason, age alone provides a poor basis for assessing the condition.

 

The best way to determine if the cable is in good condition or not is to perform a condition assessment.

 

There are several different methods for this and each has its advantages and disadvantages.

 

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For less critical cables, an Online PD survey may be sufficient. This will reveal any weaknesses in end terminations, cable or joints as long as these weaknesses generate partial discharges at normal operating voltage.

 

However, this will not reveal whether there is PD triggered by overvoltage. There will also be limitations in how far the measurements can detect activity

 

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For more critical cables, it is recommended that a monitored withstand test.This means that cable must be taken out of service. A full cable diagnosis takes between 1 and 2 hours. During a cable diagnosis, the cable is subjected to an overvoltage of up to 1.7 * U0, while partial discharge and TanDelta diagnostics are performed.

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