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The Role of CoroCAM and MultiCAM in the Development of High-voltage Defect Visualisation
Image- or pattern-recognition software is used to alert operators to In order to determine which actions should be taken with the results
unscheduled changes between successive sweeps, indicating the early from UV or IR surveys of equipment, it is necessary to:
onset of a potential problem.
• establish a list of the critical equipment to be monitored;
Utilising the Visualisation Results • establish the design criteria/safety factors for equipment and thus
Visualising the problem is still only part of the solution as the results the potential failure modes;
must be interpreted. The first prerequisite is to have those results in • develop a matrix for UV discharge/hotspot causes versus effects
pictorial form to allow easy interpretation. This means that the with actions for various situations;
• build a set of criteria for CoroCAM camera settings for taking
consistent equipment monitoring readings;
• build a database of UV discharge and/or IR hotspot values on
The technology and instruments
critical equipment under the above criteria, including the physical
available to visualise fault
environment factors;
• continually update the matrix and criteria as more data become
indicators on high-voltage
available (e.g. photon/temperature readings  versus physical
electrical systems have come a
inspection of equipment).
very long way.
The final step in utilising the results of the visualisation surveys is
to create reports that can be used to highlight the issues to
management or maintenance departments for action to be taken
visualisation systems must be capable of recording preferably both still to rectify the problem areas. Standard software packages are
images and video clips. The CoroCAM I and III cameras output video available to create such reports and most companies will have a
streams that are recorded on separate video recorders. The CoroCAM format for them. If necessary, it is extremely simple to create a one-
504 and MultiCAM have on-board still-image storage as well as the page document using any word-processing package, summarising
video output streams, allowing more effective use of the survey time. the key aspects and including images taken by the CoroCAM 504 or
MultiCAM or still images grabbed from a video recording.
It is important to understand the following when interpreting the
results from an IR or UV survey: Future of Visualisation Technology
The next steps in the evolution of visualisation technology include
• not all UV discharges or hotspots are dangerous or damaging the application and incorporation of new sensor technologies from
to equipment, but they  are an indication of some developing research programmes in the space, military, medical and nano-
abnormality; technology fields. These will inevitably lead to more sensitive (earlier
• any UV discharge or hotspot indicates at least a loss detection of smaller faults on lower voltage systems), more compact
of transmission/distribution power; and lighter systems with more features, more powerful image-
• individual CoroCAM 504 and MultiCAM camera readings are not processing capabilities and more user-adaptable features. The
by themselves conclusive, but should be used as comparisons challenge in the aerial inspection field will be autonomous flight of
within each technology; unmanned aerial vehicle systems as a way of reducing survey costs.
• there are many  HV equipment, environmental and instrument
variables that affect UV photon readings or IR temperature Another challenge will be the fulfilment of user demands for instant
readings; and analysis of the results of a visualisation process in a severity report
• any cause of UV discharge or a hotspot must be understood before and a set of recommendations for actions to be taken.
a course of action is decided upon.
Conclusion
Although the CoroCAM 504 and MultiCAM cameras have the It can be seen that the technology and instruments available to
function of counting and displaying the number of photons or the visualise fault indicators on HV electrical systems have come a very
temperature of a hotspot, respectively, these are not absolute long way from the naked eye through to the latest all-inclusive
measurements of the severity of a discharge or hotspot. No specific MultiCAM UV/IR/visible systems that can be handheld or mounted in
conclusion can be taken from a single reading due to the many a variety of ways to facilitate efficient surveys of equipment. Such
variables including distance, atmospheric conditions, camera settings systems have made the life of the maintenance engineer much easier,
and HV equipment design parameters. The cameras should rather be but at the same time have introduced new challenges in the
used as data collection systems, either: interpretation of the systems’ outputs. There is, therefore, still much
development left in the evolution of the visualisation of  HV faults
• to compare two equivalent pieces of HV equipment and highlight a through the use of UV and IR imaging technologies. n
significant difference in UV discharge activity or hotspot
temperature with the same camera settings (see Figures 4 and 5); or Acknowledgements
• to build up a picture over time of the change in UV discharge The authors wish to thank Eskom Holdings, Sustainability & Innovation,
activity or hotspot temperature reading from specific pieces South Africa and  CSIR, Materials Science and Manufacturing in 
of equipment. South Africa.
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