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Corona Scan of 115 kV and 230 kV Polymer Suspension Insulators

Advanced corona testing capabilities using new camera technology

​At the request of a client, corona scanning was done on 115 kV and 230 kV polymer insulators to determine if there was any corona or arcing present on the insulators.

Kinectrics was also asked to make recommendations on whether any corona activity detected was serious enough to warrant removal and lab examination of the insulators.

New corona camera technology

Scans were done using a DayCor® Superb Corona system camera, which is able to detect corona and arcing activity in daylight.

115 kV Insulator Scan

The corona camera was used to observe a 115 kV polymer suspension insulator which had been reported by the local utility to be generating RIV. The scan showed a very small amount of corona or arcing activity at the line end of the insulator.

The scan indicated that the insulator likely had some light contamination arcing activity, but our assessment was that it did not require any special attention.

230 kV Insulator Scan

The corona camera was used to observe two 230 kV polymer V-string assemblies located at a site in Toronto. One of the V-strings had been identified as a potential problem through thermovision scanning.

The corona scans showed significant activity on both the V-strings. Activity was focused in the area of the line-end end-fittings and the line-end shank and sheds on the insulators.

The fact that there was heating on one of the V-string assemblies identified through the IR scan and coincident corona / arcing activity identified through the corona scans suggested either serious contamination arcing or permanent non-reversible degradation such as erosion or tracking of the insulators.

The insulators were not equipped with external corona rings, increasing the likelihood of corona discharge and subsequent damage leading to heating due to erosion and /or tracking.

These V-string insulators should be removed during the next available outage and examined to define the cause of the problem.

About This Case Study

Industry Sector

  • Transmission & Distribution

Nature of Service

  • Inspection
  • |
  • Analysis
  • |
  • Testing - Field Services
  • |
  • Testing - Lab Services

Client Assets

  • Insulators
  • |
  • Lines

Kinetrics Facilities

  • Electrical Testing Facilities
  • |
  • High Voltage Laboratory


  • RIV
  • |
  • Insulators
  • |
  • corona
  • |
  • Polymer