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On-Line Partial Discharge Testing 27.6 kV XLPE Cable

Expert condition assessment to identify XLPE cables in need of urgent maintenance and / or replacement.

Client’s Objective

To identify XLPE cable runs in need of urgent attention, as well as longer term maintenance or replacement, via the ranking of the 27.6kV XLPE cable runs, in terms of high / medium / low risk.

Scope of Work

Partial discharges (PD) are essentially ‘electrical sparks’ that occur in the bulk of high voltage insulation materials. In polymeric-based cable systems (EPR or XLPE cables) partial discharges primarily occur along dielectric interfaces and / or impurities in cable accessories, such as cable joints or splices and cable terminations. 

Partial discharges may also occur within the cable insulation itself around mechanically degraded spots and / or impurities.  This results in the formation of electrical trees.

For decades, cable manufactures have used partial discharge testing for quality assurance purposes.  However, recent technological advancements in on-line partial discharge detection and instrumentation, which allows for the measurement of a range of PD parameters, has greatly enhanced data interpretation.

Work Performed

Using an in-house developed sensor coupled with an instrument, PDBase, which was developed by a European manufacturer, TechImp, Kinectrics conducted an on-line partial discharge survey of the client’s XLPE cables. 

Fundamentally, PDBase is a sophisticated data logger with three input channels which allow for sequential acquisition of partial discharge signals.