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Useful indications about the composite insulator maintenance plan main actions are shown in Table 18.
It is recommended to perform all Table 18 listed actions, as a reference starting point, at the plant start-up.
The periodical controls have to check variances or significant anomalies respect to this reference status.
Visual inspection:
Carefully check that the composite insulators sheds do not show any mechanical damages and significant
tracking or erosion due to electrical stress.
Visually evaluate also the pollution status and identify the areas of concentrated contamination.
Take note of the position of the areas of evidences, to be carefully analysed and taken under control during
future inspections. In case of evidence of incipient erosion / tracking, plan an immediate cleaning action.
UV camera and infrared examination:
Scan all the surface of the composite insulators with an UV camera to identify possible areas of intense UV
emissions on the sheds, on the toroids and the incoming cables. To perform this test, the camera must be
properly set in order to avoid false signals and background noise.
In addition, an infrared scan on the line terminal and the incoming cables can reveal incipient hot spots
phenomenon that can evolve into a serious damage on the electrical connection and then of the bushing itself.
In case of significant variation of the UV and IR emission, plan the following actions:
UV emission:
Immediate cleaning action on the interested part, in the meanwhile control all electrical
connections.
IR emission:
Immediate control of all electrical connections.
WARNING: This operation is performed with the plant energized. All specific safety procedures related to the
operation inside the valve hall must be accurately followed. The activity must be done by qualified and trained
technicians. All precautions must be followed to prevent severe accidents.
HVDC TRANSFORMER BUSHINGS
Time base
1 Year
When plant is off
Table 18 – Composite insulator maintenance plan
PHI 530.1425.2500
PHI 265.850.1500
Kepco project
X
X
IS 2664 GB
Page 31 of 70
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