E. Fred Steennis

1
THE INTRIGUING BEHAVIOUR OVER TIME OF PD'S FROM
DEFECTS IN MV CABLES AND ACCESSORIES LESSONS
LEARNED WITH SCG, an on-line monitoring system

• E. Fred Steennis
• on behalf of

E.Fred Steennis Netherlands Session 1 Paper
0875
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Content

• how to measure PDs on-line in MV cables
• some results
• lessons learned the intruiging behaviour of
  PDs
• conclusions

3
Content

• how to measure PDs on-line in MV cables
• some results
• lessons learned the intruiging behaviour of
  PDs
• conclusions

4
How to measure PDs on-line

• applied method SCG
• SCG means Smart Cable Guard

5
How to measure PDs on-line

• with SCG
• diagnose cables ( 8 km)
• data via internet to KEMA server, 1 h updates
• customers have accessto their PD plots
• KEMA experts recom-mend on action if needed

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Content

• how to measure PDs on-line in MV cables
• some results
• lessons learned the intruiging behaviour of
  PDs
• conclusions

7
Some results
4 days
PILC of 666 m with water at 396 m
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Some results
3 weeks
XLPE cable of 4.3 km with joint at 1678 m
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Some results
gt 4 weeks
XLPE cable of 7 km with various weak spots
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Some results
top view
3 months
PILC of 2.2 km with liquid filled joint at 1794 m
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Content

• how to measure PDs on-line in MV cables
• some results
• lessons learned the intruiging behaviour of
  PDs
• conclusions

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Lessons learned PDs are intruiging

• How effective is SCG?
• 4 years SCG
• 158 km cable monitored
• 41 defects found
• in 7 cases (17 ) no PD at all
• in 34 cases (83 ) clear PD activity and time
  to act
• SCG is effective in warning for upcoming failures

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Lessons learned PDs are intruiging

• SCG . . . . how much time for repair?

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Lessons learned PDs are intruiging

• SCG . . . . how much time for repair?
• water in PILC
• joints with hot conductor
• screen interruption in XLPE
• liquid filled joints in PILC

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Lessons learned PDs are intruiging

• SCG . . . . how much time for repair?
• water in PILC days )
• joints with hot conductor
• screen interruption in XLPE
• liquid filled joints in PILC
• ) between start of heavy PD activity and failure

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Lessons learned PDs are intruiging

• SCG . . . . how much time for repair?
• water in PILC days )
• joints with hot conductor days )
• screen interruption in XLPE
• liquid filled joints in PILC
• ) between start of heavy PD activity and failure

17
Lessons learned PDs are intruiging

• SCG . . . . how much time for repair?
• water in PILC days )
• joints with hot conductor days )
• screen interruption in XLPE weeks )
• liquid filled joints in PILC
• ) between start of heavy PD activity and failure

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Lessons learned PDs are intruiging

• SCG . . . . how much time for repair?
• water in PILC days )
• joints with hot conductor days )
• screen interruption in XLPE weeks )
• liquid filled joints in PILC months - years )
• ) between start of heavy PD activity and failure

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Content

• how to measure PDs on-line in MV cables
• some results
• lessons learned the intruiging behaviour of
  PDs
• conclusions

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Conclusions

• SCG can diagnose PILC, XLPE or mix
• up to 8 km, with 1 length accuracy
• exp. so far 4 years 158 km monitored
• effective to see defects on time 83 !
• PDs from many types of defects only visible for
  a few days before the failure, in others cases
  there is (much) more time
• SCG most effective if monitoring over longer time

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THANK YOU FOR YOU ATTENTION