Power cable diagnostics

DNV provides services for off-line and on-line diagnostic tests for underground power cables, after installation and during the service life

Preventing failures
Cable failures are a major cause of network outages, contributing significantly to interruption frequency and duration, and customer minutes lost. For this reason, T&D utilities need diagnostic tests for underground power cables to identify cable quality. Measurements after installation help identify defects due to improper installation, while diagnostic tests during the service life can prevent failures due to ageing and degradation.

Worldwide experience
DNV provides diagnostic tests of underground power cables for both purposes. Calling on extensive worldwide experience, we can test cables of any length, offering independent judgement based on knowledge that has been built up over many years. We carry out the tests, and interpret and analyse the measurements, providing you with insight into the present health and possibly the remaining life of the cable. Moreover, we can offer recommendations for maintenance, repair, replacement or operation based on the observed quality of the cable.

Testing
Tests can be off-line (with the cable disconnected from the grid and powered by an external source) or on-line (with the cable connected to the grid and powered by the grid).

Tests available:

• Off-line withstand test according to HD 620, IEC 60502, IEC 60840, IEC 62067
• Off-line partial discharge test according to DNV standards
  • Reflection based (with one sensor at one cable end) up to about 3 km cable length
  • Non-reflection based (with sensors at both cable ends and with GPS time sync of the two sensors) up to about 10 km cable length
• On-line partial discharge monitoring (Smart Cable Guard)
• Off-line Tg delta (loss angle) test according to DNV standards
• Off-line dielectric spectroscopy (DS) according to DNV standards