Laborelec carries out condition assessment on rotating electrical machines as part of its mission to assist in operating and maintaining power plants and other industrial installations.
For this kind of task, ultraviolet (UV) detection of partial discharges is fast, easy to carry out and interpret, and offers a high level of safety in high-voltage situations. In short: it’s an investigation tool of choice.
Detecting partial discharges is widespread as a way of estimating the condition of the stator winding insulation in high-voltage rotating electrical machines. Measurement can be achieved electrically – in-service or offline – but alternative complementary methods are also available on the market, such as UV detection. For some years, Laborelec has been using an OFIL Systems-branded UV camera in a wide range of situations involving power generators and motors, in power plants and other industrial sites.
When increased levels of partial discharge activity are detected (for example through in-service electrical measurement), it is common for additional measurements to be undertaken during an outage to clarify or confirm the diagnosis.
Laborelec regularly uses an OFIL Systems’ UV camera to assess various failure mechanisms. The camera allows immediate and safe localization of the origin of superficial corona discharges on end windings, for example, when generators are disassembled during planned outages.
When local repairs are carried out on end-windings, it is useful to compare certain features or measurement results before and after the repair. In a recent case, OFIL Systems’ UV camera was used on a large turbogenerator to verify that Corona discharges had decreased and that repairs had been carried out successfully. In addition, the UV camera is able to carry out this verification from a safe distance.
When an HV motor is dismantled to make the stator winding accessible in a workshop setting, the UV camera greatly assists in identifying
problems. In particular, the camera helps locate superficial partial discharge issues from a safe distance. This is important since such tests are carried out in the presence of high voltages.
The above images are from a recent case where a clear increase in external partial discharge activity, compared with previous measurements, was detected. In this case, as in the others, the UV camera made it possible to pinpoint the source of the partial discharges on the terminal leads from a safe distance.
This improved the reliability of the diagnosis and gave more credibility to the repair recommendation.
Listen to Andrew Rizzetto, Service Line Manager, Field Services of Overhead Lines at Kinectrics HV lab talk about how assessing corona partial discharge in electrical substations leads to cost savings and extends the life of overhead lines.
He talks about the extensive testing he does of line hardware, structures, insulators, switches, and connectors using a daylight corona camera, such as the OFIL Systems’ Luminar.
“Corona on an overhead transmission line can cause power loss, increased audible noise, electromagnetic interference, installation failure, equipment failure, and environmental concerns.”
Meet Ivan Boev, Principal Engineer at Kinectrics HV lab.
At Kinectrics, OFIL Systems’s Luminar UV camera is one of the main tools used to test for corona partial discharge in the high-voltage lab.
In this video, Ivan highlights the significant impact this camera has had on their operations: it pinpoints Corona partial discharge sources in full light, ensuring the equipment’s health and reliability.
Ofil develops and manufactures UV Bi-spectral optical and digital inspection systems with embedded proprietary patented Solar Blind technology. Ofil aims at providing precise solutions for science, industry and environmental wellness. Ofil owns the brand name DayCor® that stands for Daytime Corona detection.
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